Anal. Chem. 1983, 55,214R-232R (99) Biggs, J. T., Tricyclic Antidepressant Plasma Measurements In Clinical Practice. I n "Interpretations in Therapeutic Drug Monltorlng"; Baer, D. M., Dlto, W. R., Eds.; American Society of Clinlcal Pathologists: Chicago, IL, 1981; pp 150-160. (100) Dugas, M., Zarlflan, E., Leheuzey, M., Rovei, V., Durand, G., Morselli, P. L., Therap. Drug Monit. 2 , 307-314 (1980). (101) Braithwaite, R. A., Dawling, S., Montgomery, S. A., Therap. Drug Monit. 4, 27-31 (1982). (102) Schaub, J. S.,Lithium. I n "Interpretatlons In Therapeutic Drug Monitoring"; Baer, D. M., Dito, W. R., Eds.; American Society of Clinlcal Pathologists: Chicago, IL, 1981, pp 161-168. (103) Sashldharan, S. P., Therap. Drug Monit. 4 , 249-264 (1982). (104) Reeves, D. S.,Infection 8 [SUPPI.31 8 , 313-320 (1980). (105) Garagusi, V. F., Clin. Lab. Med. 7 , 585-597 (1981). (108) Dito, W. R., Aminoglycosides and Therapeutic Drug Monitoring. I n Interpretation in Therapeutic Drug Monitoring"; Baer, D. M., and Dito, W. R., Eds.; American Society of Clinical Pathologlsts: Chlcago, IL, 1981; pp 187-203, pp 253-261. (107) Matzke, G. R., Gwizdala, C., Wery, J., Ferry, D., Starnes, R., Therap. Drug. Monit. 4, 195-200 (1982). (108) Bleyer, W. A., Therapeutic Drug Monitoring of Methotrexate and Other Antineoplastic Drugs. I n "Interpretation In Therapeutic Drug Monitoring"; Baer, D. M., Dito, W. R., Eds.; American Society of Cllnlcal Pathologists: Chicago, IL, 1981: pp 169-186. (109) Sadee W., Therap. Drug. Monit. 2 , 177-185 (1980). (1 10) Bastlani, R., Wilcox-Thole, W. L., Recent Developments in Homogs neous Enzyme Immunoassay. I n "Cllnical Laboratory Annual"; Homburger, H. A,, and Batsaki, J. G., Eds.; 1982; pp 289-338. (111) Falk, L. C., et al., Clin. Chem. 22, 785-788 (1976).
(112) Flnley, P. R., Williams, R. J., Clin. Chem. 23, 2139-2141 (1977). (113) Brown, L. F., et al., Clin. Chem. 24, 1032 (1978). (114) Fruchart, J. C., Kora, I., Cachera, C., Clavey, V., Duthilleul, P. Moschetto, Y., Clin. Chem. 28, 59-62 (1982). (115) Theofilopoulos, A. N., Dixon, F. J., Hosp. Prac. 5, 107-121 (1980). (116) Klein, M., Siminovitch, K., J . Rheumatol. 8 , 188-192 (1981). (117) Kreiger, D. T., Yamaguchi, H., Llotta, A. S.,Adv. Biochem. Psychopharmacol. 28, 541-556 (1981). (118) Krelger, D. T., Llotta, A. S.,Brownsteln, M. J., Zlmmerman, E. A,, Recent frog. Horm. Res. 38,277-344 (1980). (119) Merrill, W. W., Bondy, P. K., Clin. Chest. Med. 3, 307-320 (1982). (120) Bilezikian, J. P., Am. Intern. Med. 9, 198-202 (1982). (121) deBoer, A. C., Genton, E., Turpie, A. G. G., Chemistry and Clinical Significance of Platelet Specific Proteins, CRC Grit. Rev. Clin. Lab. Sci. 18, 183-211 (1982). (122) Kniker, W. T., Toward More Precision in Allergy Practice Comparison of Diagnostic Approaches In Resplratory Allergy. I n "Rast in Clinlcal Allergy"; Fadal, R. G., Nalebuff, D. J., Eds.; Year Book Medlcal Publishers: Chicago-London, 1981; pp 71. (123) Nalebuff, D. J., Fadal, R. G., and Ali, M., Immunology & Allergy Practice 3, 18 (1981). (124) Chretien, M., Seldah, H. G., Scherrer, H., Can. J . Physiol., Pharmacol. 59,413-431 (1981). (125) Marymont, J. H., Herrmann, K. L., Laboratory Med. 73(2), 83-91 (1982). (126) Edman, D. C., Craven, R. B., Brookls, J. B., Gas Chromatography in the Identification of Mlcroorganlsms and Diagnosis of Infectious Diseases, CRC Crif. Rev. Clin. Lab. Sci. 74, 133-161 (1981). (127) Nurse, G. T., Clin. Haematol. 70, 1051-1067 (1981).
Ferrous Analysis W. A. Straub" and J. K. Hurwitz United States Steel Corporation, Research Laboratory, Monroeville, Pennsylvania 15 146
This review is produced from a search of the literature as performed with the DIALOG capabilities of Chemical Abstracts Service. The material covered in this particular review is a continuation of past reviews by the same authors and covers the period from September 1980 to October 1982. It is obvious that the level of activity in the publication of research results by analytical chemists and spectrographers in the steel industry is significantly reduced and directly reflects the malais that affects our industry. Without being overly critical, we will have approximately 300 less literature citations in this review as compared to the last one (448).
ALUMINUM Total trace aluminum was determined spectro hotometrically in some unalloyed and low-alloyed steels a ter appropriate dissolution steps as an Eriochrome Cyanine R complex (98),by using Chromazol KS as a color-formingagent (269), as a colored complex with salicylidene-o-aminophenol-4sulfonic acid (523), and with l-pheny1-2,3-dimethylpyrazolone-5-azopyrogallol(13). Low levels of A1 have been determined in high- and lowalloy steels and ferrovanadium by atomic absorption after separation from the matrix by electrolysis (94). The determination of acid soluble aluminum by AA continues to be a very popular method in the steel industry by virtue of its rapidity (51, 76,511). Low concentrations were also determined in silicon steels by using electrothermal atomization (245). Direct injection of a dissolved steel sample into an AI-H flame has been reported (282). AA has not supplanted emission spectrochemical methods for this determination as they continue to be used for both soluble and insoluble aluminum determinations in steel (135, 304). One method involves the premelting of a selected zone on a sample surface in an inert atmosphere so as to concentrate the insoluble aluminum inclusions in the surface of the remelted zone upon which the surface is mechanically removed and subsequently analyzed spectrally for the soluble portion (76). A design for an instrument has been claimed that eliminates anomalous emission spectrometric signals from aluminum inclusions, thus permitting the determination of acid-soluble A1 with high precision (452).
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Various other procedures have been applied in a general way for the analysis of steel and related materials and include the use of lasers for localized sampling prior to spectral excitation (208,311), Grimm glow-dischargesource excitation (466),ICP emission spectrometry (15,101),an acid dissolution, ignition, and NaF fluxing prior to dc arc excitation for stainless-steel analysis (299),and the use of dc plasma techniques for iron ores, sinters, and dust analysis (369). The accuracy of XRF spectrometry for determining A1 in low-alloy and stainless steels (at 0.1% carbon in nonalloyed steels has reportedly been performed by X-ray fluorescence spectrometry (91) although another paper described a number of experimental parameters that must be controlled in order to measure carbon in plain C steel and cast iron by XRF technology (186). The use of a total-reflectance mirror monochromator for the XRF determination of C in iron and steel has also been discussed (517). Electrolytic extraction of carbides from high-speed and related tool steels has been used to allow a comparison of the bulk carbon content with individual carbide content. The determinations were performed by a combination of XR,F and X-ray diffraction techniques (222). A recent study aimed a t evaluating seven commonly used sample molds far sampling cast irons for C analysis recommended a disposable ceramic ring on a chill plate and the addition of a carbon stabilizer to the sample spoon for improved repeatability during subsequent vacuum emission spectrometric analysis of the sample (516). Problems associated with the determination of low (0.001 to 0.01%) carbon in steels by emission spectrometry and the importance of using a reference technique and reference materials were underscored in a recent review (240). A magnesium counterelectrode has been recommended in a method used for the emission spectrometric determination of carbon in wires and welding electrodes (348). Various parameters influencing the accuracy and precision of the emission spectrometric determination of carbon by Grimm-glow discharge excitation have been discussed (466). Surface roughness and type of cast iron samples did affect the determination of carbon in this class of samples by Grimm-glow discharge excitation according to another report (300). Sampling by up-hill casting and high-frequency spark excitation in an argon-hydrogen protective atmosphere have led to improved analyses of pig iron by emission spectrometry for process control purposes (406). For the determination of C in high-speed steels, it was found that sample melting and recasting with fixed time integration emission spectrometric analysis of the resulting remelted specimen still required special calibration curves for the carbon determination (345, 462). Carbon has reportedly been determined in molten steel by a combination atomizer-lance working in the steel melt to produce a steel powder that is transported pneumatically to a UV emission spectrometer for plasma excitation (396). Carbon has been determined at low levels (5 ppm detection limit) in several NBS SRM steels with lithium-6 heavy ion activation analysis measurements (342), and in various coke-Fe ore and cokeslag mixtures by neutron activation with a plutonium-beryllium source (449). Carbon distributions on steel and stainless-steel surfaces were measured by several new secondary ion mass spectrometers according to two recent papers (145, 182). In the same vein, electron microprobe investigations of the carbon content and or distribution on clad steels (78), in carburized parts /202{, in carbonitrided or carburized low-alloy steels (395),in low-alloy and alloyed steels (394),and at interfaces in high-P stainless steels (490) have been described in the recent literature.
CHROMIUM This element lhas been determined in steels by the extraction and spectrophotometric measurement of its complex with tetraphenylarsonium chloride into CHC13 and 1,2-dichloroethane (26),as the peroxo-4-(2-pyridylazo)resorcinol complex extracted into ethyl acetate ( I l l ) , in the infrared region as the isothiocyanato-pyridinecomplex (in the presence of the comparable iron complex) (103),and in ores at the trace level as the ternary complex with diphenylcarbazide sodium p-toluenesulfonate ( 1 74). A procedural change has been recommended and applied to the spectrophotometric determination of Cr in steels that should increase the sensitivity of any of the above methods (90). An ion-exchanger has been synthesized and applied to the separation of Cr from FeCr prior to its determination (133). IR spectroscopy was used
to study and ultimately to reduce the amount of Cr(V1) in fumes from the welding of stainless steels (226). Variations of the iodine-sodium thiosulfate titration procedure for the determination of trace levels of Cr in steel have appeared in which the iodine was generated coulometrically (65) or photochemically (89). For high levels of Cr, a reductimetric titration with ascorbic acid, using a benzohydroxamic indicator, has been described (8). The explanation for the high results obtained by using the ASTM method Ifor the titrimetric determination of Cr in steels, cast irons, etc. has been given in a irecent publication (40)and an empirical factor is recommended to correct these results. Amperometric titration with 2,4-dithiobiuret has been used for the determination of Cr(V1) in steel (485) as has titration with the reagent 1-naphthylamine (492). The complex of Cr(II1) w t h Eriochrome Cyanine R has also been exploited for the cletermination of chromium in steel (367,368)at the 0.97 to 4.3% level. Electrolytic oxidation in a phosphate medium at pH 7 was recommended for the determination of metallic chromium on chromatecl steels (142). An electrochemical separation was used to provide sufficient sample for the deteirmination of chromium (up to the 10% level) in differently treated steels by flame atomic absorption spectrometry (442). With regard to the direct determination of chromium in solution from a dissolved steel sample, the effect of iodine in eliminating interferences in the AA flame has been studied (193,194). Alternative procedures have also been described that start with a preliminary extraction before excitation in an AA flame. These include the use of diphenylcarbazide (28)and tribenzylamine (93)as extractants for the analysis of iron and steels. Emission spectrophotometric methods for the determination of chromium in carbon steel wire by arc excitation (381) and in welding wires (338) and alloy steels at the 2.5 to 7% level (45) by spark (excitation (348) have appeared. Interferences in the emission spectral analysis of high-speed steels have been eliminated by remelting and recasting of the origirial samples with standard steels (345). Laser sampling has been applied to the analysis of various ferrous materials as a prelude to their final analysis3 by emission s ectrophotometric methods. Among the methods describefare the arc excitation of laser-sampled slags and steels (31I ) , the determination of (3 as low as 0.08% in mild steels (3),and trace levels in low-alloy steels by a combination of laser ablation and inductively coupled plasma spectrometry (211,472). Generalized methods have also been described that employ inductively coupled plasma excitation as applied to acid solutions of steels (15, 141) and stainless steels (213,284). In one case, the addition of a hydrophilic solvent up to 5 vol % has improved the determination of Cr (213). A comparative study was made of the use of spark source excitation and glow-dischargeexcitation for the determination of Cr in steels at the 0.001 to 2% level and the methods were found to be equivalent (96). Proton-induced X-ray emission spectrometry has been applied to the determination of a number of elements in alloy steels (450). Descriptions of other multielement X-ray fluorescence procedures for the analysis of iron alloys continue to appear. Of interest are the use of a cellulose support during XRF analysis for a portion of an anodically dissolved sample (290),the direct analysis of solid samples by XRF method (308, 309), and the use of both on-line and in-lab XRF determinations for the sorting of steels for quality control purposes (502). The application of X-ray fluorescence in combination with appropriate sample fusion methods has been shown to be comparable to chemical methods for the analysis of the main components of several ferroalloys including FeC!r (200). Remelting under an inert gas atmosphere with subsequent centrifugal casting has also been used for the preparation of several ferroalloys for XRF analysis (409). In another approach to sample preparation, ferrous alloys that contain Cr have been subjected to a preliminary furnace oxidation to remove carbon prior to their analysis for chromium content (475). A review was published recently that discusses the application of XRF spectroscopy for the determination of coating thickness on tin- and chromium-coated steels (110). In this regard, a Japanese patent claims the development of an XRiF method for the determination of the amount and thickness of surface films by the analysis for a specific element present in the film (480). Corrections for the same element present ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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in the substrate are provided. Reference Fourier transform infrared spectra of surface oxides on 310 stainless steel have been shown to be valuable in complementing other data in identifying these films (356). Corrosion films on coal liquifaction vessel steel (411) and on stainless steel nuclear reactor vessels (61) were analyzed by ESCA techniques and by glow-discharge spectrochemical techniques, respectively, for their Cr content or profile. Auger analysis has been applied to the determination of Cr in and on fracture surfaces of austenitic stainless steels (180). Thin oxide films on binary Fe-Cr alloys have been studied by secondary ion mass spectrometry (375) as has the bulk concentration of Cr in steel (182) and surface concentration profiles of various elements, including chromium in steel-mill dust particles (488). Proton-induced prompt y-ray spectrometry was compared favorably to XRF methods for the determination of minor elements in steels (136,364). Finally a standard reference steel with 18.1% chromium has been characterized by electromicroprobe microanalysis (278) as to its homogeneity.
COBALT Spectrophotometric methods were reported for the determination of cobalt in low-alloy steels with 3-(2’-thiazolylazo)-2,6-diaminotoluenein acid sodium acetate with V03 (!28), with 2-nitroso-1-naphthol-4-sulfonic acid (297), with salicylaldehyde thiosemicarbazone (389), and in high carbon and (531). alloy steels with 5-((2-pyridyl)axo)-2,4-diaminotoluene Spot-testing reactions for several elements including cobalt in high-alloy steel have also been described recently (43). Trace quantities of cobalt have been determined by airCzHzflame atomic absorption after first removing most of the iron by extraction (371),while potassium pyrosulfate-hydrogen sulfate fluxes were used as both the decomposition agent and spectroscopic buffer to eliminate matrix effects in the direct determination of cobalt in steel by AA (478). Fixed time integration techniques were used for the spectrochemical analysis of heat-resistant steels (462) and were also coupled with HF-induction melting-centrifugal casting of high-speed steels with known amounts of standard steels in order to minimize spectral interference effects (345). ICP spectrometry has also been applied to the determination of alloying elements including cobalt and the standard conditions are given (141). Cobalt in the range of 250 to 2500 ppm has been determined in stainless steels following dissolution of chips or millings in acid, conversion to an oxide mixture by ignition, and fluxing with graphite and NaF prior to excitation in a dc arc (299). As an indicator for sorting steels for quality control purposes, an X-ray fluorescence method has been applied to the determination of cobalt in order to establish an intensity-ratio figure with respect to known control standards (502). Proton-induced prompt y-ray spectrometry was used to determine minor levels of several elements, such as cobalt, in steel, following irradiation (364). Electrochemical dissolution of a steel specimen and subsequent fixing of a portion of the resulting solution on a filter paper for an XRF determination was used to establish a procedure for classifying various alloys (290). Proton-induced X-ray emission analysis was also applied to ferromanganese nodules for a multielement determination of the sample, and the results were verified independently by AA and emission spectroscopic techniques (228). Several methods of sample preparation were studied for the quantitative determination of cobalt (and other elements) in ferromanganese nodules by electron microprobe analysis (445). Cobalt impurities in reactor steels were measured by neutron activation analysis after a 3-day decay period (533).
COPPER Michler’s thioketone has been the subject of two papers describing its use for the determination of copper in steel (281, 373). Interferences and detection limits are covered. Cu forms and a 1:l complex with 5 4 (2-pyridyl)azo)-2,4-diaminotoluene it has been exploited for the analysis of high-C and alloy steels for trace quantities of this element (531), while an extraction-photometric method has been described that uses 6-(2quinolylazo)-3,4-dimethylphenolto measure copper in steels (385).
A number of procedures and methods have been written that cover the determination of copper in various steels and 218 R
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alloys by a variety of emission spectroscopic means. Among those of interest are a comparative study of glow discharge lamps and spark sources for the routine analysis of steels (96), the spectrometric analysis of wire and wire rod (381), spectrochemical analysis of stainless steel following dissolution, ignition and trituration with a fluoride salt and graphite prior to excitation (299), the centrifugal recasting of high-speed steels before emission spectral analysis (345),fixed-time integration-emission spectral analysis of heat-resistant steels (463), an evaluation of various sample molds for the analysis of cast iron by vacuum emission techniques (516), and the application of inductively coupled plasma emission spectrometry for the analysis of iron ores (101) and stainless steels (284).
Several different sample preparation techniques as well as direct analysis were used for the atomic absorption analysis of various steels. In one case, electrochemical isolation was employed to produce enough sample in solution for the determination of Cu in differently treated steels (442). KHS04 and K2S607were effective as fluxes for the rapid decomposition of steel prior to an AA analysis with an air-CzH2 flame (478). Direct atomization from a graphite cup was reportedly used for the determination of copper in steels (460) and low alloys (33), in the latter instance, after separation and complexation with neocuproine. X-ray fluorescence methods are continuing to be used for the determination of traces of copper in various ferrous materials, such as in ferromanganese nodules presented as thin sample targeta (228), in steel following anodic dissolution and subsequent absorption on a filter paper disk (290),and directly in steels and cast iron (309) and high-carbon steel and highchromium cast iron and steel (308). The copper content of brass-coated steel tire cord wire has been measured by a rapid XRF method (491),and a combined SIMS/AES/XPS method has been described for steel tire cord quality control purposes (420). Secondary ion mass spectronietry has been used for the surface analysis of steel furnace dust particles in combination with XRF for their bulk analysis (488). Several methods of sample preparation were compared for the electron microprobe analysis of Pacific Ocean ferromanganese nodules (445).
EMISSION SPECTROMETRY A recent study was undertaken to provide information on the appropriate choice on internal standards to use with inductively coupled plasma excitation, and yttrium was found to be the most satisfactory (102). Another study was performed to assess the precision and accuracy of ICP emission spectrometry by using certified standard steels and alloys. The results were compared to XRF spectroscopy for the same standards (370). Interelement effects were elucidated by a comprehensive study of a series of binary ferrous alloys by emission spectrometric techniques (179), while sample preparation and other experimental conditions were discussed for the emission spectral analysis of cast irons and low carbon and high alloy steels by vacuum quantimetric methods, and a new cast iron sampling mold was designed as a result of this work (441). A high energy discharge pretreatment was found beneficial in the emission spectrometric analysis of free-cutting steels with large amounts of inclusions (328). The use of a preburn period with a high energy spark was said to improve the accuracy and precision of the emission spectrometric analysis of pig iron with significant amounts of precipitated graphite (99). For high-speed steel analysis a high-frequency melting and subsequent centrifugal recasting in combination with fixed time integration emission spectrometric or XRF analysis was found to be effective in producing improved results (344, 346). The fundamental characteristics and performance of the magnetic field Grimm glow discharge source were described in two recent papers with reference to mild steel and stainless steel analysis (247,248). Recent progress in the use of glow discharge excitation in the iron and steel industry has been described (82),as has the use of and problems with this source for the analysis of cast irons (123). The use of emission spectrometry for the sorting of various steels has been quantified by the development of a parameter derived from the frequency distribution of selected intensity ratios (83). Computer-aided automation in the emission spectrometry
FERROUS ANALYSIS
laboratory is the subject of three papers that cover the logging of data, its evaluation, and its transmission to the central laboratory computer when appropriate (49, 159, 403). Ion microscopy has been applied at the microlevel to characterize the homogeneity of standard reference low-alloy steels for their further use as standards for microprobe analysis and other microonalytical techniques (489). In a comparison of three sampling methods for the analysis of stainless steels by X-ray fluorescence spectrometry,the total dissolution method was found preferred to the partial dissolution method or the electrographic method of sampling (461).
GASES (HYDROGEN, OXYGEN, NITROGEN) Problems in the sampling, measurement, and the use of reference materials in determining hydrogen in nonalloyed steels have been discussed in a recent review (236). In a recent Japanese development, the use of a preheater has been recommended for the removal of any adsorbed moisture prior to the determination of hydrogen (214,216). During the X-ray microanalysis of !steel samples, the hydrogen released by the electron beam bombardment has been measured quantitatively by application of a quadrupole mass spectrometer (320). A sampling mold for the determination of both diffusable and nondiffusable hydrogen has been evaluated for the analysis of several grades of steel including high alloys. The determination was finished by a thermal conductivitymeasurement (254). Another study of the sampling of liquid steel with a. combination quartz-staidess steel tube sampler reported that hydrogen losses were minimized and the subsequent vacuum hot-extraction analysis gave higher results than the conventional quartz method (303). The hydrogen content of low-alloy steels was determined by either vacuum extraction, inert gas fusion, and anodic dissolution, and the latter method gave results several times higher than the other two (357). Vacuum extraction has been applied to the determination of hydrogen in zinc-plated sheet immediately after the zinc has been removed by amalgamation (201). Hot extraction was also applied to the measurement of H, in steels with a differential manometric finish (224)and to the determination of diffusible hydrogen in weld metal (350). Programmed temperature control has been combined with a gas chromatographic measurement to determine the hydrogen releasable from steels and welded joints (322). Gas chromatography in conjunction with vacuum extraction was also used for the determination of hydrogen in an examination of enameled steels containing Ti and V (104). In another modification of the high-temperature extraction of H2 from iron and steel in which only the sample is heated during the extraction step, either a mass spectrometer or a gas chromatographic finish was used to determine the released gas (456). For the determination of atomic and molecular hydrogen in steels, an electrochemical method involving the liberation of H2 by anodic dissolution has been developed. The reaction of atomic hydrogen with 2,2,6,6-tetramethyl-4-hydroxypiperidinyl-1-oxyl[R-1-tanol], with and without the presence of a platinum catalyst was used to differentiate between the forms of hydrogen present (230, 231). An electrochemical measurement of hydrogen desorption rate has also been applied to the determination of the forms of H2 in steels (521), as has a water displacement method for the measurement of just the diffusible Eorm in arc-welded specimens (404). Alloys have been ranked according to their hydrogen permeability or absorption rate as measured by mass spectrometricmethods (473). Three reviews have appeared discussing oxygen sensors of the electrochemicalconcentration cell type with emphasis on principles, construction, and applicability to the steel industry. They are written in Japanese (1441, Czechoslovakian (433), and German (377). A Chinese study has appeared in the literature dealing with improvements in the reliability of electrochemical oxygen sensors as used in electric furnace steel melting (272). A number of patents have been issued describing the development of various modifications of the electrochemical oxygen sensor based on the use of solid electrolytes and metal-metal oxide reference half cells and include contributions from Japan (124,169)and Germany (29, 30, 112, 113). Several other published reports have appeared and cover the use of oxygen sensors, primarily of the zirconium-oxide type,
for the determination of oxygen in steels (69, 185, 189),in rimmed steels (293),in cast irons (246),in magnesium-treated or cerium-treated cast irons (178),and in basic oxygen co:nverter slags (212). In one of the above references, a slide rule was described from which EMF and temperature measurements could be directly converted to oxygen values (69). Reductive vacuum fusion extraction of oxygen from highalloy steels was reportedly enhanced by crucible design changes and the use of a Ni-Sn addition to minimize secondary absorption effects on the recovery of oxygen (260). In another variation on this approach, hydrogen reduction of a heated steel sample was used to produce an amount of water equivalent to the oxygen content of the steel (324). The use of argon carrier gas %withhigh-frequency induction melting of the steel sample and subsequent determination of the evolved CO (after conversion to COJ by a coulometric titration of the acidity produced in the absorber has been described for the determination of low oxygen levels (170). Another interesting study of thie carrier gas fusion method incorporated a nonaqueous absorbiing solution for collection of the evolved carbon dioxide and itq determination with a titrimetric finish. Sucrose was found to by entirely suitable as a standard reference material to calibrate the instrument (518). For the simultaneous determination of nitrogen and oxygen in steels, a combination vacuum fusion-quadrupole maris spectrometric method was designed that incorporated the use of a programmed temperature furnace to measure the gas extraction curves (205). This study was extended to cover the decomposition mechanisms of various nitrides and oxides likely to be found in steels as second phases (206). Partsper-million levels of nitrogen and oxygen have been determined in steels and stainless steels by an isotope dilution mass spectrometric method (352). Surface oxides and their effect on the results were discussed. In a general study of iron powders from various sources, gas evolution was measured over a temperature range of 25-600 "C. Gases detected include COz, 02,CO, Nz, HzO, and CH4 (410). A recent paper detailed the results obtained in an interlaboratory comparison of various methods for the determination of nitrogen in steels. A fusion-extraction method was useld as the referee method (153). The development of a versatile sampling system said to simplify and shorten sample preps.ration and/or pretreatment has been described for the determination of nitrogen in steel and been adapted for use on both induction heating and pulses heating inert-carrier fusion analysis systems. Analysis time has been reduced by 50% and the possibility of atm'ospheric contamination of samples has been eliminated (232). Mobile or diffusible nitrogen in steels has been determined after it has been extracted by reaction with hydrogen to form ammonia. The extracted ammonia was measured directly b y a spectrophotometric method (14)and by the measurement of the absorbance of %-chloro-4-nitrophenolthat dissociates upon the addition of ammonia (164). A variation of the reductimetric method for the evolution of mobile nitrogen by reaction with hydrogen at 450 "C used an iron oxide catalyst to promote the formation of ammonia (27). An NH3 ion selective electrode was employed to make the ammonia measurement in the buffered absorber solution, An electron microprobe method has been described fo.r determiningsmall amounts of nitrogen in steel. Fe4Nwas used as the standard to permit quantitation of results (38). Finally, high-energy deuteron bombardment of Nitronic 33 alloy has been used to produce a proton yield proportional to the nitrogen concentration (218).
HALOGENS With regard to the analysis of steel for their halogen content, most of the work reported centers on the detection and de.. termination of various 'halides on surfaces and in surface films.. Small amounts of fluoride in corroded stainless steel were determined by precipitation separation, complexation, andl extraction to permit a colorimetric finish. Microgram quam tities were determined in this manner (467). X-ray fluorescence analysis of steel. plate surfaces enabled the detection of chloride at the 10 ng/cm+ level. Light rust did not affect the measurements (486). A rapid on-site method has been described for the semiquantitative determination of chloride! from a known area of riteelwork with a sensitive colorimetric: test (507). ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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Compleximetryhas been used for the measurement of high amounts of fluoride in steel-making sla s (196),while a sensitive XRF method was used successfulfyfor the determination of fluoride in hydrated Cr oxide coatings on tin-free steel (181).
INCLUSIONS Two recent reviews have been written dealing with general problems and methods of phase analysis of nonmetals in steels (235) and the application of electron microscopy in combination with selective chemical and electrochemical etching for the identification of nonmetallic inclusions (378). Another review with 22 references described the author’s use of pdiketones in the development of potentiostatic electrolytic isolation methods for precipitates in steel (459). Fundamental studies of the extraction efficiency, reproducibility, and applicability of various electrolytic methods for the analysis of nonmetallics have appeared in a recent Iron and Steel Institute of Japan report (302). Electrochemical isolation has been used to study the carbonitrided layers of hardened and tempered steels and to characterize the types of carbides and nitrides present (46), while both chemical and electrochemical methods were used to separate V and Nb carbonitrides in precipitation-annealed structural steels (353). Two reports were published describing the use of C1-citrate electrolytes for the isolation of Fe, Cr, Mo, and Mn carbides from alloy steels (339),and other carbides from high-W steels (223). In an interesting reference pertaining to the development of apparatus and electrolytes for the isolation of carbides from low-alloying and microalloyed steels, the stability of the isolates was enhanced by carrying out the electrolysis in a refrigerator (249). Carbides of Nb, Ti, V, Mo, and Zr in carbon and stainless steels were observed and analyzed by application of the SPEED method which involves measurement of polarization curves of these compounds developed during a nonaqueous potentiostatic etching of the isolated compounds (258). Single-sweepvoltammetry has been applied to metallographicallypolished thin sections of high-speed steels in a highly alkaline electrolyte as a means of determining M3C and M& carbides (70). Physical methods that have been used for the characterization of various carbides include scanning transmission electron microscopy and energy-dispersive X-ray emission spectrometry for embrittled Cr-Mo steels (298) and alloy steels (172) with Ti and Nb additions, Auger electron spectrometry for the quantitative analysis of cast stainless steels (343),and a time-of-flight mass spectrometer used as an atom probe for the microanalysis of carbides in Cr-Mo steel (287). The isolation of nonmetallic oxide inclusions from steels has been studied and two modifications of the traditional electrochemical method have been developed and found to give improved precision (312, 313). An investigation has been described that covered the effect of electrolyte pH, temperature, and the presence of various complexing reagents on the electrolytic isolation of A1N from silicon-steel samples, and recommendations are given for optimizing the procedure (527). In another fundamental study recently reported, the thermochemical pro erties of various nitrides and oxides (Si, AI,Fe) were studieiby programmed temperature vacuum fusion analysis (206)in graphite and steel crucibles. Anodic dissolution was employed to isolate nonmetallic phases from austenitic steels to enable a determination of the distribution of nitrogen between the nonmetallic and metallic phases (52). The stable oxide and silicate inclusions were also characterized. For the more direct determination of the chemical forms of nitrogen in steel by the hydrogen hot extraction method, sample form (coarse, fine, thin, thick) has been found to be a very critical parameter in the procedure (471). A study was made of the chemical and electrochemical stability of FeS and MnS as related to acidity and electrical potential, confirmingthat the isolation of sulfides from steels requires neutral or weakly basic electrolytes at a carefully controlled potential (217). Exactly these conditions were used in the determination of sulfide distribution in cold-rolled steels (115). Sulfides in steels (259) and phosphides in stainless steels (257) have both been studied by the SPEED method (nonaqueous electrolytic potentiostatic etching) A recent trio of papers described the use of an electron beam source with a relatively large diameter beam and which in I
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conjunction with surface scanning of the specimen permits the graphical display of the two-dimensional distribution of sulfide and phosphide inclusions (326, 327, 436). By careful measurement of the electrolysis current used to anodically dissolve a steel specimen and with knowledge of the composition of the metal specimen, an accurate assessment of the inclusion content can be made as described in a recent Japanese patent (318). In another variation of the traditional electrolytic isolation method for the extraction of oxide inclusions from carbon and alloy steels, controlled temperature chlorination was used to purify the inclusion residue before analysis (534). Finally, automation has come to the isolation of inclusions through the development of a completely automatic electrolytic extraction system that includes a sample changer, cell, potentiostat, solution injectors, sonic vibrators, and a timer. Twelve steel samples are analyzed in sequence with this instrument (464).
IRON Hematite levels in Fe ores have been measured by monitoring the diffuse reflectance at two wavelengths over the range of 5-25% Fe203(429). Metallic iron in reduced ores has been determined after separation by dissolution with p-diketone and measurement of the spectrophotometricabsorption of the resultant solution (459), by a voltammetric method that utilizes the ores in a paste applied to an electrode surface (426), and following dissolution of the metallic portion of the Fe in a FeC13 solution and direct titration with Na2S203(286). Modifications of the traditional dichromate titration used to determine iron in ores have been developed to allow the elimination of the use of mercury (530). In another chemical determination of Fe in ores, an EDTA release method with subsequent determination of the released complexing agent has been described (479). Controlled potential coulometry using the oxidation of Fe(I1) to Fe(II1) (47) and coulometric titration of Fe(II1) with electrogenerated Cu(1) (314)have been used for the analysis of ores and ferrovanadium, respectively. Amperometry with a K2Cr20, titrant has been used for the determination of Fe(I1) in oxidized pellets at the 0.15-1.5% Fe(I1) level (107).A recent Polish study has been published that evaluated several alternatives of sample dissolution prior to analysis, and it indicated that the method based on acid dissolution is simpler and more precise (198). Alternative methods for the determination of Fe in slags from electroslag melting have been evaluated and outlined in another recent Polish paper (196). Extraction procedures for the determination of Fe(II1) have been expedited by the development of an automatic apparatus that can com lete an extraction in about 20 s (316). 2Hydrox -3,5-t$methylacetophenone has been used as an indicator goth for the chelatometric titration of Fe and for the direct spectrophotometricdetermination of Fe(II1) in iron ores (190). The simultaneousdetermination of Fe and Cr in Fe-Cr alloys has been reported, using their isothiocyanatopyridine complexes and their absorption in the infrared region (103). Iron at the 40 to 95% level in steels has also been determined in electrochemical isolates by AA spectrometry in air-C2H2 flames (442). In a recent comparison of dc plasma spectrometry and X-ray spectrometry, the latter method gave better accuracy and precision in the determination of iron, iron ores, and sinters (369). A similar comparison of XRF and chemical analysis for iron content in finely divided sinters has also appeared (338). Routine applications of XRF for the analysis of iron ores by powder sample techniques (109,432) and by the glass-beam method (120)with discussion of various fusion techniques and the effect of combined water content (121), with the use of natural and synthetic standards (199), with corrections for the effect of indeterminant components (203), with the use of two excitation sources for the purposes of matrix corrections (207), and with a dilution method using known additions of ZrOz to ore samples (225) have been described. Energy dispersive and wavelength dispersive X-ray fluorescence spectrometry were compared for iron ore and blast-furnace slag samples and the iron results obtained were comparable by both methods (97). Fe levels in various alloys were determined for the purposes of classifying the alloy by transferring a small portion of the
FERROUS ANALY!SIS
sample to a filter paper disk by anodic dissolution prior to XRF analysis (2%)).Direct XRF analysis of several ferroalloys for the main components compared favorably with conventional chemical methods in a recent publication (200). Alloy steels and deepsea ferromanganese nodules have both been successfully analyzed for iron content by proton-inducedX-ray emission spectrometry (228, 450). Microanalysiis was performed on Type 304 stainless steel by both energy-dispersive X-ray spectrometry and electronenergy loss spectroscopy for the purpose of determining Fe:Cr:Ni ratios in the steel (74). Electron-microprobeanalysis was also used in homogeneity studies of SRM 479A stainless steel (278). Severely corroded coal liquefaction vessel steel was studied by ISSCA to characterize the reactions that might have led to the high corrosion rate observed. Fe and Cr depth profiles were constructed (411). Polished sections of whole ferromanganese nodules were also sub'ected to total analysis by electron microprobe techniques (4453,while thin oxide films on a heat-treated refractory alloy were quantitatively analyzed by secondary ion mass spectrometric methods (375). Stainless steel surfaces contaminated with iron can be examined by using a solution containing (NH4)2Sz08and sulfosalicyclic acid to reveal the iron as its reddish purple complex (292). Major elements in Saudi ores were determined effectively by instrumental neutron activation techniques as described in two recent papers (386, 387), while the iron content of magnetite ores was determined by y-ray scattering after appropriate corrections were made to accommodate variations in sample density (360). A thermal neutron irradiation technique has been developed and applied to the simultaneous determination of Fe and A1 in iron ore fines on a moving rubber conveyoir belt ( I 71),while an americium-241 y-ray source has also been used for monitoring the iron concentration in ore concentrates on moving belts (397). The preparation of ore samples for the determination of iron by magnetic methods (354)and an automated apparatus for determining FeO content by magnetic methods (319)have been described i~na recent paper and patent.
LANTHANIDES Arsenazo I11 continues to be the favored reagent for the determination of total rare earths in alloys and ores with a prior extraction step (57), as a complex in the presence of molybdate (440),and with the use of Complexon I11 to eliminate interferences (455). Several new reagents have also been used for the determination of the rare earth group. One report describes an extensive study of the use of the reagent 2-((3azo)carboxyphenyl)azo)- 7 -((2-phosphono-4-chlorophenyl) 1,8-dihydroxynaphthalene-3,6-disulfonic acid and its colorforming characteristics w t h 16 rare earths (361). This reagent was applied to the analysis of steels and cast irons. In another study, Chloropliosphonazo 111-cetyltrimethylammonium bromide was used to determine the total rare earths in alloy steels (64). Traces of rare earth mixtures (La, Sm, Eu, Ho, and Yb) that were used to determine the origin of exogenous inclusions in steel were isolated by extraction, purified by coprecipitation, and determined by neutron activation analysis (176). Similarly, traces of La, Ce, Pr, Nd, Sm, and Eu were separated from carbon steel samples by extraction of the bulk of the iron, evaporated to dryness, and taken up in a minimum of acid to be injected into the nebulizer of an ICP source for spectrometric analysis (393). The preparation of nodular or vermicular iron samples prior to their emission spectroscopic analysis was aided by the addition of Te, Se, or S to fix the cerium and minimize its effect on the analysis (376).
LEAD The effects of various acids and other experimental conditions were investigated for the atomic absorption determination of Pb in transformer, carbon, and alloy steels by the graphite cup method (1391,while traces of Pb in microamounts of steel were also determined directly at the part-per-million level by this technology (367,168,460). Numerous repetitive atomizations were shown to be possible. Separation of lead from steels by hydride generation with either direct or indirect measurement by AA was described, and both were found acceptable for lead determinations (191). A combination ion-exchange-AAmethod has also been reported for the de-
termination of traces of lead in steels (422). Coherent forward scattering spectroscopyhas been applied to the determination of P b in steels at the parts-per-million levels without prior separation (165). Proton-induced X-ray emission analysis has been applied directly to the multielement analysis of ferromanganese nodules and the results were verified by AA and (emissiontechniques (228). Depth profile analyses of steel mill dusts were accomplished by SIMS and did show that Pb was enriched at the surface of the Darticles studied (488). Finely divided Fe-Nb alloys were mixed with a carrier and analvzed directlv for P b content bv emission sDectromet,ric metGods (520) &d by direct excitkion of chips or millings in a hollow cathode lamp (470). In two other procedures, stainless steel samples were dissolved, ignited, and fluxed with NaCl (279) or NaF (299)before dc arc excitation and determination of Pb content. A rapid polarograph was applied to the determination of Pb in free-cutting steels with no interference from copper and tin (528).
MAGNESIUM A comprehensive study of sample molds as used for the analysis of cast irons by vacuum emission spectrometry has been published and recommendations are given as to the preferred methods t o be used (516). The fixing of nodular or cast irons prior to emission spectroscopic analysis to prevent the formation of Mg-tellurides has been described (376). A Japanese study dehicribes the pretreatments necessary to DreDare BF slam and dolomites for subseauent magnesium andysis (427). SPADNS has been used for the direct determination of maenesium in nodular cast iron samDles with triethanolamine andYEGTA-Zn as masking agents (272). For iron ore analysras, after the removal of iron by flotation of precipitated Fe(OH)3, magnesium in the filtrate was determined by AA in a C2H2-air flame (524). Dc plasma excitation emission spectrometry and X-ray fluorescence spectrometry were used sequentially for the analysis of iron ores, sinters, and other steel mill dusts. The first method was recommended for the Mg analysis (36!3). Alkaline borate fluxing was employed to prepare iron ore samples for emission spectrometric analysis with ICP excitation (101). X-ray fluorescence analysis of steel plate surfaces for trace levels of magnesium was possible even in the presence of' a light coating of rust (486). X-ray spectrometry was also applied to the determination of major oxides, such as MgO, in sinters (338), to a number of ores with a powder sample preparation technique (log),and in deep-sea FeMn nodules prepared as thin sections (228). The chemical analysis of steel slags containing large amounts of fluoride has been detailed and an analytical outline presented (196).
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v
MANGANESE As has been the case in all of the 8 years that we have been compiling this review,,this element is again mentioned in more of our literature citations than any other. It is no doubt a sign of the importance of this element in steelmaking that it continues to be the subject of analytical research and developmental work on a worldwide basis. O f note in the few references to the spectrophotometric determination of Mn in stainless steel was the use of the sodium periodate oxidation method in an automatic spectrophotometric analyzer (283)and the use of silver nitrate to accelerate the oxidation reaction (215). Another study coilfirmed the statistical equivalence of the MnO, spectrophotometric procedure and the atomic absorption method with prior removal of the bulk of the iron in the sample by solvent extraction (68). The direct atomization and atomic absorption analysis of steels from a graphite-cupcuvette were studied and conditions optimized for the microdeterminationof Mn by this technique (460). Prior fluxing of steel chips with KHS04 and K2S207 was used in another study of sample preparation for an oxidizing flame AA determination of manganese in steel (478), while electrochemical isolates from steel were also used to provide a sample for analysis by flame AA (442). A detailed description of component interactions during the flame AA analysis of high-alloy steels for their Mn content and recomANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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FERROUS ANALYSIS
mendations to minimize them have been iven (152). Coherent forward scattering spectrometry has %eensuccessfully applied to the determination of Mn in steels (166). Manganese has reportedly been measured in Fe-based materials by using the polarographic reduction wave of Mn(II1) at a dropping mercury electrode. Iron was removed by a preliminary solvent extraction (244). For higher Mn levels, benzohydroxamic acid has been used in a direct stepwise reductimetric titration method for the analysis of several BCS steel standards (8). A schematic outline has been developed for the analysis of high-fluoride slags that includes the determination of Mn by a hotometric method (196), while a rapid and precise m e t h o t using the potentiometric titration of Mn with KMn04in a pyrophosphatemedium, has appeared and been applied to iron ore and steel analyses (80). Generalized methods for the determination of Mn in high-carbon steels and high-chromium cast irons and steel by direct X-ray fluorescence spectrometry have been optimized (308, 309), while in a less accurate XRF procedure, Mn in various alloys has been determined after being transferred to a filter-paper disk by anodic dissolution in what amounts to a nondestructive alloy class identification method (290). A direct steel sorting method, using the comparison of the X-ray fluorescence spectra from a specimen vs. a control standard has also been applied (502). Problems associated with the XRF determination of major components in ferroalloys such as Fe-Mn have been successfully addressed with the use of sample fusion or melting and recasting techniques (200,409). Similar problems in the XRF analysis of samples with minor amounts of Mn that are normally powders or that can be reduced to powders such as cast iron, sintered iron, or blast furnace slags have been solved by mixing the sample with binders such as paraffin wax or cellulose (535) or by pelletizing the powder with KN03 (97) prior to the determination of the manganese. Thin sample targets of ferromanganese nodules have been assayed for manganese content by proton-induced X-ray emission (PIXE) spectrometry, and the results were verified by both flame AA and emission spectrometric techniques (228). PIXE has also been compared to prompt y-ray spectrometry for the determination of Mn in steels (136). The technique of proton-induced prompt y-ray spectrometry was also used for the determination of minor levels of Mn in some standard steels (364), while neutron activation followed by high-resolution y-ray spectrometry has also been applied to the determination of manganese in stainless steels (72). In a comparison of XRF and emission spectrometry with a dc plasma for the determination of Mn in iron oxides, the XRF method was found to be more accurate and precise (369). The emission spectrometric measurement of manganese in wire samples has been reported, using both arc (381) and high-frequencyspark excitation (348). General multielement emission spectrometric or spectrographic methods for alloy steel analysis (45) and heat-resistant steel analysis (462) have been outlined in recent publications. Optimum conditions were developed and described for the inductively coupled plasma excitation and spectrometric analysis of iron ores following fusion and subsequent acid dissolution (101) and for alloy steels (141) and stainless steels (284). Laser vapor generation in conjunction with ICP emission spectrometric analysis has been used for the determination of trace Mn in low-alloy steels (211) and in conjunction with arc excitation, for the analysis of slags and steels (311). Grimm glow-discharge excitation has been strongly recommended for the determination of Mn in cast irons (300) and in corrosion f i i s on reactor stainless steels (61). A comparison of glow-dischargeexcitation and spark source excitation for the routine analysis of steels showed that detection limits for Mn were equivalent (96). Finally, for the rapid analysis of molten steel for its manganese content, a method has appeared that uses an atomizing lance directly in the furnace to produce a steel powder that was then transported pneumatically at least 30 m to a plasma excitation source for subsequent UV emission spectrometric analysis (396).
MISCELLANEOUS ELEMENTS Silver in ferroalloys and steel (470) was determined by emission spectrometry, using a computerized image dissector echelle spectrometer. The spectra were excited in a hollow cathode lamp filled with helium. In addition, silver was de222R
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ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
termined by atomic absorption in steel (460) by using direct atomization of the solid sample in a graphite-cup cuvette. Selenium and tellurium were determined in steel by hydride atomic absorption (503,505). Because of a difference in valence states, analyses of spiked samples were in poor agreement with certified standard samples, but this effect was minimized by peak area integration. Tellurium has also been determined in steel with spectrophotometric (16) and X-ray fluorescence (245) methods and in cast iron with inverse voltammetry (204). Argon in steel has been determined with a hot extraction technique followed by thermal conductivity measurements (405). Hydrogen, nitrogen, and carbon monoxide, which interfere with this determination must be separated before the measurement. Uranium in steel below 10 ppm has been determined (63, 86) by the particle track analysis method using solid state nuclear track detectors. Rhenium (305) and scandium (439) have been determined in steel and steel alloys by spectrophotometry. Ores were analyzed for mercury and strontium by emission spectrometry (382) and X-ray fluorescence (228).
MOLYBDENUM Extraction-spectrophotometric methods for the determination of Mo at the parts-per-million level in steels have been published that use 2-thiopyrogallol in isoamyl alcohol or 0mercaptoresorcylicacid in isoamyl alcohol as the extractants (18, 19), or 5,7-dibromo-8-hydroxyquinoline in CHC13 for stainless steels (48) or N-rn-tolyl-p-methoxybenzohydroxamic acid in CHC13 for alloy steels (134), or thiocyanate with stannous chloride in CHC13 (276). Alcoholic bromopyrogallol red and cetyltrimethylammonium bromide have been used to form a red complex with Mo following its separation from iron and steel samples by ion exchange (265). Two other studies appeared that dealt with the interaction of Mo(V1) with pyrogallol red and cetylpyridinium chloride (296) and bromopyrogallol red and cetylpyridinium chloride (402) both for the determination of Mo a t the parts-per-million level. Other reagents used for the extraction-spectrophotometric measurement of Mo include 3,4-dihydroxyazobenzenein nitrobenzene (499)and dimethylaminophenylfluorone (71). The last-named reagent compared favorably to SCN- methods. A paper also appeared that described the use of a nonionic surfactant in combination with SCN- to stabilize the Mo complex (160). a-Benzoine oxime in MIBK was used to extract Mo from a dissolved steel sample prior to its determination by NzOCzHzflame atomic absorption (62). KHS04-KzSz07fluxes were used to prepare steel samples for the direct determination of Mo by AA at the trace level (478), while acid dissolution preceded the AA determination of Mo at the 3.2% level in tool steels (262). A special molybdenum-blue coated electrode, cathodically polarized, was reportedly used as the indicator electrode for the titrimetric determination of Mo with N-aryl derivatives of hydroxylamine as titrants (44). A procedure was also developed for the oscillopolarographicdetermination of Mo in steel (255). High levels of Mo in steel (5.5%) were separated by ion-exchange technology with subsequent gravimetric measurement as the 8-hydroxyquinoline complex (267). High-frequency spark source excitation was employed for the emission spectrographic determination of trace Mo in welding electrodes (348) and at higher levels in alloy steel by the same type source (45). Three studies appeared outlining the conditions for the application of inductively coupled plasma excitation to the detection and measurement of molybdenum in iron and steels (15,141) and in stainless steels (284), while the glow discharge source has been tested successfully for a depth study of corroded stainless steels (61) and for the routine analysis of alloy steels in a comparison with spark excitation of these same steels (96). In the case of high-speed steels, a melting and recasting of the original sample has been found to provide comparable results to the established emission spectral method (345). Molybdenum at the 1 to 5% level in high-alloy steels has been determined by X-ray fluorescence spectrometry by using a single calibration graph based on standard reference materials (336). Lower levels of Mo have also been determined directly both in steels and cast iron by XRF techniques (308, 309). On-line and laboratory sorting methods, based on the
FERROUS ANALYSIS
use of XRF, have been developed and applied to sort various steels based on their Mo content (502). Iron alloys have been semiquantitatively analyzed by transferring a portion of the alloy onto a filter paper disk by anodic dissolution prior to XRF analysis (290) for the major components present. Ferro alloys such as Fe-Mo have reportedly been both prefused with appropriate fluxing reagents before XRF analysis for their main components (200) or they have been melted and centrifugally recast as a means of preparation for final XRF analysis (409). Proton-induced X-ray emission techniques have been applied to the determination of Mo and many other trace elements in deep-sea ferromanganese nodules (228). Two reports have been published detailing the use of neutron activation analysis techniques for the determination of some trace elements in stainless steels (72) and the use of particle-induced (5-MeV He+) prompt photon emission with an intrinsic Ge detector for the measurement of Mo in steels (136).
NEW METHODS AND APPARATUS As is usually the case, there are always a few literature contributions that do not necessarily fit the format we have chosen and that fall into the category of novel developments that should be mentioned for completeness. Included in this class are two references to the development of mobile or portable spectrometers and their application to the routine on-site analysis of steel products (54,239).In order to predict the future corrosion rate of nuclear structural components, a portable, computerized laser microspectral analysis system was developed for the almost nondestructive determination of elements such as silicon on metal surfaces (2). Work is continuing in the development of a spectrometric analysis system that can be applied directly to molten metals. The absorption spectra of the vaporized metal is the key in this claim (347). For the localized analysis of metal samples, laser irradiation and subsequent mass spectrometric analysis of the volatilized products have been described in a recent patent (325). Two patents lhave been issued claiming the development of an apparatus and methods for the automated electrolytic dissolution of metal turnings (332)and solid specimens (331). The latter method is said to be particularly effective for hard-to-dissolve samples.
NICKEL Extraction-photometric methods for the determination of nickel in various steels and alloys have been reported and have been implemented with the use of the following reagents: by extraction with N,N-bis((ethoxythiocarbony1)thiomethyl)aniline separately or with dithizone to form the measured colored complex (12),by ion-exchange separation on a strongly basic resin and color formation with butanedione dioxime (270),by extradion with 1-(2-pyridylazo)-2-naphtholin the presence of a solubilizing emulsifier (384), and as an extractable complex with purpurin (392). A method, using the whole sample rather than an aliquot, has been recommended for improving the sensitivity of spectrophotometric and extraction-spectrophotometric methods used for the determination of Ni in steel (90). Nickel(I1) trifluoroacetylacetonate has been used for the ligand vapor gas chromatographic separation and analysis of nickel in steels (119). Greater than 1% nickel has been rapidly determined in steels and alloy steels by titration with EDTA with a murexide indicator (465). Acid dissolution was used to prepare an 8-20% nickel steel for direct atomic absorption (after dilution) analysis (250), while an electrochemical dissolution technique was used in another procedure (442) and potassium hydrogen sulfatepotassium pyrosulfate fusion was used as both a flux and spectral buffer iiri third AA method for steel analysis (478). Extraction was combined with a nondispersive atomic fluorescence method (that used a graphite furnace for excitation) for the determination of 0.01-4% in iron and steel samples (253). As would be expected,the determination of nickel in various types of steel is most readily performed by emission spectrometric methods, and there has been no shortage of published reports. Arc excitation (381)and spark excitation have been applied to the analysis of welding wires and rod (348) and to alloy steels (45). Slags and steels have been sampled
locally with a laser pulse prior to arc excitation (31I) and to provide a metallic vapor for subsequent ICP emission spectrometric analysis (211). Conditions have been reported for optimizing the determination of Ni in stainless steel (284)amd in alloy steels (141) by ICP emission spectrometry. The suppression of interference effects though the use of spectroscopic buffers was reported to improve the sensitivity of a UHF plasma torch emission spectrometric determinatiion of Ni in steel (10). Recasting of high-speed steels by using a high-frequency induction melting furnace with centrifu,gal casting of the resultant melt was coupled with a fixed time integration emissioin spectrometric method to improve the determination of Ni in this matrix (345). Glow-discharge lamps were investigated as an excitation source to study the corrosion depth of various stainless steels (61) and for the determination of 0.001-2% Ni in various steels and alloys (66). X-ray fluorescence analysis has been used for the determination of Ni in steels and cast irons (308, 309) and as a means of sorting steels based on the differences in compositiion (502),both on-line and in the laboratory. Alloys were also assayed by XRF by first dissolving a portion of the sample electrochemically onto a filter paper disk before the XRF analysis (290). Ni-Zn alloy coatings electroplated on steel were measured both as to amount and composition by an XliF method (453). Electron microprobe microanalysis has been used to qualify an Fe-Cr-Ni alloy as a standard for microanalytical methods (278). Type 304 stainless has been studiied by energy dispersive X-ray spectrometry and electron energy-loss spectrometry and the composition ratios determined by each method were compared (74). Quantitative results were also reported for the determination of Ni in Fe-Mn nodules as measured by electromicroprobe analysis (445). Residual nickel films on a stainless steel substrate were determined by dissollution of the film in nitric acid and subsequent chemical determination of the nickel stripped (118). Auger analysis was applied to the determination of various elements including nickel on a fractured stainless steel surface (180).
NIOBIUM Research continues in the development of new or modified methods or reagents for the spectrophotometricdetermination of niobium in various steels and related materials. In stelels (415 ) , the reagents p-sulfobenzeneazo-4-(2,3-dihydropyridine) a tartrate and 2-((5-bromo-2-pyridyl)azo)-5-(diethylamino)phenol complex (425),and 5,7-diiodo-8-hydroxyquinoline(41'8) were applied to the determination of microgram amounts. In the case of stainless steels, thiocyanate extraction into BuO Ac (188) and p-sulfobenzeneazo-4-(2,3-dihydroxy-5-chloropyridine) (416)have been used to effect a spectrophotometric measurement of niobium. Microamounts of niobium on carbon and alloy steels and in high-speed steels have been determined by the use of diazotized m-sulfonitrophenol couacid (515) pled with 4,5-dihydroxy-2,7-naphthalenedisulfonic and xylenol orange (19.9,respectively. The heteropoly acid blue system (phosphorus-molybdenum-niobium blue-rhodamine B) was applied to the assay of iron ores for trace quantities of this element ( 1 73). Sample fusion techniques for the preparation of various ferro alloys such as Fe-Nb were investigated in order to dlevelop a procedure for the X-ray fluorescence spectroscopic analysis of this class of materials (200),while another study relied on dissolution, ignition, and pelletizing with boric acid to prepare Fe-Nb for XRF analysis (148). Minor trace levels of niobium were determined in heatresistant steels by using a fixed time integration emission spectrochemical method (462),in stainless steels with a dissolution, ignition, and flux spectrochemical method (299),in welding wires by a high-frequency spark source excitation method (348),and in a corrosion study requiring a profiling of concentration with depth in reactor stainless steel by glow-discharge excitation (61).
PHOSPHORUS A number of variations of the well-known phosphomolybdenum blue method for the determination of pholsphorus in ferrous materials have been described in the recent literature. Among thlose given are included the separation of all interfering species from the phosphorus of interest (as HZPO,) by a column chromatographic separation with a ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
223 R
FERROUS ANALYSIS
subsequent elution of the phosphorus and determination as the molybdenum blue complex (81). In another procedure interfering Nb, Ti, and Zr were removed by cupferron extraction from the dissolved high-temperature alloy before the P was determined photometrically (525). Several direct methods have been described for the determination of P in steel, cast iron, and nodular iron in which thiourea (264) or ascorbic acid and Sb (155)have been used to stabilize the color (264). Various experimental parameters related to the selectivity, sensitivity, and stability of the phos homolybdenum blue method have been discussed (366,458 with reference to steel and slag analysis. The complex phosphorus-molybdenum blue-Rhodamine B has been applied to the determination of P in steels and cast iron (519) at the 0.04% level. Conditions for the interference-free atomic absorption determination of phosphorus in steel by the graphite furnace method have been described (506),as has a method for increasing the sensitivity of this same determination by coating the graphite rod furnace with zirconium carbide prior to the excitation step (220). A recent paper described the optimum working parameters for the Spectraspan I11 determination of P in steel (50),while methods for the correction of interferences in the emission spectrometric determination of P in steel have been based on studies of a series of binary alloys (275). A low-voltage ac spark source with a copper counterelectrode was reportedly used for the determination of P in steels and cast iron (335). In a recent report the application of a combination atomic absorption/atomic emission spectrometerto the determination of P in steel was studied and a method optimized (408). Another ICP application for this same determination recommended the use of lower UV wavelengths for the measurement of P in steel so as to obtain an improved signal to background ratio (501). It has been shown that a system can be developed for the assay of molten iron for its P content by the combination of an atomizer operating on the melt with subsequent transfer of the metallic powder produced to a plasma excitation source for analysis (396). Fused and dissolved samples of iron ore were reportedly analyzed by ICP emission spectrometry at the rate of 2 min/sample with good precision as compared with conventional chemical analysis (101). Spark source excitation and Grimm glow discharge were compared for the routine analysis of steels and found to be comparably sensitive for the detection and measurement of P (96),although in another study of the use of glow discharge for the analysis of cast iron, surface roughness affected the P working curve (300). The applicability of this same type of source for steel analysis with regard to reproducibility, interferences, and accuracy has also been discussed (466). Two recent Japanese publications covered the use of X-ray fluorescence spectrometry and its optimization for the determination of trace levels of P in steels and cast irons (79, 309). Powdered or ground samples of pig iron were treated by methods developed for the handling of other powdered materials and the resultant procedure was recommended for routine analysis of this matrix (535). Recent work with Fourier transform interferometry has indicated its usefulness in studying phosphate coatings on iron surfaces and their chemical reactivity (158).
SELENIUM Interferences in the determination of hydride-forming elements such as selenium by atomic absorption spectrometry were studied, and it was concluded that higher acid levels promoted interference-free determinations in low-alloy steels (503,505). Sample collection on membrane filters with interference removal prior to X-ray fluorescence analysis was applied to free-cutting steels (210). An interesting electrochemical precipitation-dissolution method was described that used a preliminary separation of selenium as copper selenide on a graphite electrode prior to its electrochemical dissolution (256).
SILICON Several methods have been employed to determine silicon. Spectrophotometry has been used to analyze slags (196), carbon and low-alloy steels (291,513),and stainless steel (283). Emission spectrometry was used for the analysis of carbon and low-alloy steels (3, 45,88, 311, 348, 380, 381,458), cast 224R
ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
iron (300, 516), ores (101, 369), slags (311), and steel alloys (345). Volumetric analysis for determining silicon in slags (196) and mass spectrometry in steel (182, 288) were used. Silicon was determined by X-ray fluorescence in ores (109, 121,199,228,338,369,497), stainless steel (EO),carbon and low-alloy steels (308,309,486), cast iron (308,309), and pig iron (535). Determination of silicon in surfaces was described with secondary ion mass spectrometry (182) and atom probe microanalysis (288). Proton-induced y-ray spectrometry (364) and radiochemical separation (468) methods were used for determining trace concentrations of silicon in carbon and low-alloy steels. Silicon was determined in steel and cast iron by the amperometric titration of molybdosilicate with diantipyrylmethane in acid media (310) and by direct-injection enthalpimetry (53).
SODIUM, POTASSIUM, THALLIUM, AND RUBIDIUM All of the above elements have been determined in deep-sea ferromanganese nodules by proton-induced X-ray emission spectrometry with verification by either flame AA or emission methods (228). In a separate investigation of ferromanganese nodules, thallium was extracted with ammonium pyrrolidinedithiocarbamate with a subsequent determination of the T1 in the extract by AA spectrometry (183). Iron ores, cements, and coals were analyzed for their thallium content by either injection, graphite furnace, or platinum-loop atomic absorption spectrometry or by inductively coupled plasma atomic emission spectrometry (35). A similar study of the analysis of a variety of materials used in the steel industry concluded that flameless atomic absorption was superior to the other techniques in determining trace levels of thallium (401). Sodium and potassium were determined in iron ores and sinters by atomic absorption with an &CzHz flame (424).
SULFUR A recent review has traced the transition of methods for the determination of sulfur in iron and steel (355),while the major methods now in use for the determination of low levels of sulfur in steel have been critically compared (240) and recommendations made. Two separate studies have appeared concerned with performance evaluations of the LECO SC 32 sulfur analyzer (388) and the RANK HILGER E 200 InfracarbS analyzer (379)with particular reference to the determination of sulfur in slags, ores, sinters, agglomerates, and steels. A recent LECO patent deals with the determination of scaling factors required to correct for the inherent nonlinearity of the IR detector used in sulfur analyzers (55). A combustion-SOz evolution analyzer for the determination of S in steel has been described that uses the decolorization of iodized starch in conjunction with an automatic digital readout system (365). A second Chinese publication describes an automatic double arc combustion of h i g h 4 steels with titration of the evolved SOz with NaOH (162). In another variation of the combustion sulfur method, the thermite process was employed to convert sulfur in the molten steel produced by the reaction into SO3 with subsequent titration of the evolved gas with barium perchlorate (39). Reductive decomposition of heated steel samples in a hydrogen stream has been used to convert S into HzS for detection and measurement in a flame photometric detector (330). By use of pyrolysis of steel or iron samples in a reducing solution with inert gas purging, H2S can be evolved and measured rapidly by UV absorption spectrometry as claimed in recent patents (321,349). A variation of this approach for the analysis of blast furnace slags for sulfur content with an iodometric finish has also appeared (390). In a comparative study of the glow discharge lamp and spark source excitation for the determination of sulfur in steel, the glow discharge had lower detection limits for sulfur and was not influenced by sample surface condition as was the spark source (96). However, sample type and surface roughness did affect the working curve for sulfur in cast irons with glow discharge excitation (300). The general applicability of Grimm-glow discharge to steel analysis has also been tested, and conditions for its successful use were outlined (466). The Perkin-Elmer ICP-5000 has recently been evaluated and parameters optimized for the interference-free determination of S in steel
FERROUS ANALYSIS
(408). Trttce levels of S have also been determined in heatresistant steels by a fixed time integration emission spectrochemical method (462). The sulfur content of molten steel has been measured by atomizing a sample from the melt with a special lance arid transporting the resultant powder at least 30 m for plasma excitation and analysis (396). In a recent study of sample molds for cast iron analysis, the ceramic ring-Cu chill plate method was recommended for obtaining a sample for emission spectrometric examination (516). Conversely,the conversion of pig iron samples to powder by grinding in a protective atmosphere has been recommended for routine application in the determination of S by XRF analysis (535). Two papers of general applicability have appeared covering the use of X-ray fluorescence spectrometry for steel and cast iron analysis (309) and the determination of S in metallurgical coke after homogenization with an organic binder (435). A method employing isotope dilution spark source mass spectrometry hai been applied to the determination of sulfur in several JSS and NBEZ standard samples and the results compared favorably with results obtained by other methods (398). Auger spectrometric analysis has been used effectively for the determination of sulfur segregation on broken tool steel surfaces (161),on fractured austenitic stainless steel specimens (180), and on titanium-coated 304 stainless steels (483,484). A swab test has been described for the detection and semiquantitative determination of sulfates on structural steel framework in which the separated sulfate is measured colorimetrically with Ba rhodizonate (507). Finally, for the rapid determination of S in molten steel, a sensitive electrochemical method has been described that compares the EMF developed between the sample and an ionic conductance solid electrode sensitive to sulfur and BL reference electrode with a fixed S potential (234).
SURFACES Aside from the numerous references that have been cited in the other subsections of this text, there are other citations of a more general nature that describe the application of various analytical techniques to the characterization of steel surfaces. Included in this category are studies of the principles and characteristics of Grimm glow-discharge optical spectrophotometry for the purpose of analyzing oxidized, decarburized, pickled, nitrided, and phosphided surfaces (36,340). In the same way, hollow cathode discharge has been used to effect a layer-by-layer analysis of oxidized surfaces (151). For the study of surface layers on stainless steel and cold-rolled sheet, ESCA AES and the ion-microprobe mass analyzer were used (122). wo reviews have been published devoted to the problems associated with the use of quantitative AES in the analysis of fractured surfaces (131) and the use of electron, ion, and X-ray microprobe analyses for studies of surface layers on nitrided steels (493). Ion microprobe analytical techniques have been reportedly applied to the determination of surface oxides on steel (451) and the determination of wear reduction in stainless steels following the implantation of nitrogen (508). The use of a defocused primary-ion beam has enabled the analysis of the outermost layers of a variety of alloys by the SIMS technique (446). In a study of the effect of high concentrations of H2Son the surface of stainless steel at various times and temperatures, both infrared reflectance spectrometry and, laser Raman spectroscopywere used in situ to determine surface reaction products (105),while Raman backscattering spectroscopy was successfully applied in studies of the high-temperature oxidation and hot salt corrosion of 310 stainless steel and similar alloys (106). A general review has been written describing the application of various surface analysis techniques for the study of lubrication phenomena
4
(130).
Nitrogen depth distributions on steel surfaces were determined by the L4N(d,p)16N reaction to a depth of about 15 pm (87), arid on nitrided surfaces by a combination of sample dissolution in acid, and subsequent evolution of the resulting ammonia SO it could be measured by an ammonia-specific electrode (476).
TANTALUM Trace levels of tantalum in steel have been determined spectrophotometrically as the stable purple complex with
bromopyrogallol red in the presence of cetyltrimethylammonium bromide (454) and at the 0 5 5 % level in steel as (419) the complex with 5-chloro-8-hydroxy-7-iodoquinoline and in stainless steel at this same level with 5,7-dinitro-8hydroxyquinoline (413). Heat-resistant steels were analyzed for minor trace elements including tantalum by a fixed time integration-emission spectrochemical method (462). Small amounts of tantalum in Fe-based alloys were directly determined by a new potentiometric method that utilizes, a TaF,-sensitive electrode. A standard addition technique was used to minimize ionic strength effects (526).
TIN Extremely low levels of tin in carbon steel, alloy steel, cast iron, and pure iron were determined spectrophotometrically as the ternary complex with pyrocatechol violet and cetgltrimethylammonium bromide (510) and by the extraction of SnIl prior to color development with 2,2'-diquinoxalyl (31'). Ion exchange separation was used to quantitatively isolate 53n from transformer iron samples so as to permit its spectrophotometric measurement with phenylfluorone (60). Atomic absorptioin spectrophotometry has been applied indirectly to the determination of tin in iron and steel by first extracting it as its iodide and subsequently back-extracting it prior to flame AA analysis (92). For the direct determination of tin in transformer, carbon, and alloy steels, electrothermal or graphite furnace methods have been studied and applied to steel chips and saimples dissolved in acids (139,233,337). Hydride generation methods have also been widely used for the determination of Sn in various ferrous materials and studies have focused mainly on the effects of interferences (503,505),and the ur3e of sodium borohydride to produce the hydride for flame excitation (282,522). Hydride generation was also employed in connection with an argon plasma burner to routinely determine tin in low-alloy steel by an emission spectrometric method (438). Trace amounts of tin have also been determined directly in steels by an emission spectrochemical method with arc excitation (279) in stainless steels (299) and in finely divided and fluxed Fe-Nb alloys (520). Tinplate samples with wood grain and black stains were profiled with Auger spectroscopy in conjunction with ionsputterin (192), while tin-coated sheets were examined fior porosity y! an electrochemical process that detected any exposed Fe by a sensitive current measurement or the appearance of hydrated oxide (482). A review with 17 references has appeared discussing the use of XRF for the determination of Sn coating weight thickness on steel sheets (110).
TITANIUM As usual, this element is readily determined by spectrophotometric means and this year's review shows no dearth of methods. Trace titanium in stainless steel was determined by extraction as the 1-phenyl-3-methyl-4-benzoyl-5pyrazalone-SCN- complex (59), in alloy steels as the 4-(2thiazoly1azo)resorcinolcomplex (126), in ores and steels
