at 330 '385 Inp and 410 '520 mp were bpecific for D.1 and NE, respectively, under the oxidation conditions used (IS, 19). ?\'one of the three amines contributed t o the fluorescence of the other two. Endogcnous value$ obtained for the amines in the presence and absence of 50 pg. each of the precursor amino acids, are com1)arahlf to other values reported (Table 11). Our values have been corrected for recovery. Alteration of endogenous amine levels by the administration of reserpine was used as a test for the sensitivity of the method. We observed the following per cent depletions of brain amines in mice sacrificed 1 hour after reserpine (Ciba Pharmaceutical Co., Summit, lu'. J.) 5mg./kg. 1.P.: 5HT, 50%; S E ! 61%; 11.1, 947;. It has been reported that the weak cation exchange resin CG-50 retains 5HT, D h , and KE, and permits quant,itative separation from their precursors (3, 1 4 , 16). lrnder our experimental conditions this resin yielded a quantitative vparation of 2 pg. each of S I T , DA, and ?;E from 50 pg. each of DL5 H T P (Calbiochem), L-DOPA (Calbiochem) L-a-methyldopa (3lerck Institute for Therapeutic Research, Kest Point, Pa.). The endogenow amines from 0.75 gram of brain tissue were also separated from 50 pg. each of BHTP, DOPA, and a-methyldopa. This method can be used for tissues other than brain. Lung, heart, and ~
intestine have been analyzed satisfactorily. .ketone estraction of 5HT from blood is unsatisfactory, possibly because the carbohydrate which precipitates during acetone estraction adsorbs the 5HT. ITe inferred this to be so when attempting t o assay for 5HT from sucrose-gradient fractionation of 5HTcontaining particles. ACKNOWLEDGMENT
We are grateful for the assistance of Paul T. Clark; and for the suggestions, guidance, and criticism of our colleague, Dr. Hermann F. Schott. LITERATURE CITED
(1) Albrecht, P., Visscher, 31. B., Bittner, J. J., Halbert, F., Proc. Soc. Ezptl. Riol. .\led. 92, 703 (1956). ( 2 ) .4min, .4.H., Crawford, T. B. B., Gaddum, J. H., J . Physiol. ( L o n d o n ) 126, 596 (1954). (3) Awapara, J., Davis, T'. E., Graham, O., J . Chromatog. 3, 11 (1960). (4) Bartlet, A. L., B r i t . J . Pharmacol. 15,
140 (1960).
(5) Bertler, A , , Carlsson, A . , Rosengren, E., Acta Physiol. S c a n d . 44, 273 (1958). (6) Bogdanski, D. F., Pletscher, A , , Brodie, B. B., Udenfriend, S . , J . Pharmacol. Exptl. T h e r a p . 117, 82
(1956). (7) Brodie, B. B., Costa, E., Psychopharmacol. Serv. Ctr. Bull. 2 , Xo. 3, 1 (1962). (8) Carlsson, A , , Lindqvist, AI., Acta Physiol. S c a n d . 54, 87 (1962). (9) Correale, P., J . S e u r o c h e m . 1 , 22 (1956).
(10) Erbpamer,
A r c h . E x p . Pathol. Pharmakol. 196. 343 119401. (11) Fleming, 11: AI., Clark, \V. G , , Clark, P. T., Fed. Proc. 23, 491 (1964). (12) Green, H., Erickson, 11. N'., A r c h . Intern. Pharmacodynamie 135, 407
(1962).
(13) Hirs, C. H. IV., hloore, S.,Stein, \V. H., J . Biol.Chem. 200, 493 (1953). 114) Kirshner, N., Goodall, hl., J . Biol. ('hem. 226, 207 (1957). (15) Leroy, J. G., A r c h . I n t e r n . Pharmacodynamie 134, 492 (1961).
(16) Alasuoka, I). T., Drell, JV.)Schott, H. F., Alcaraz, A . F., James, E. C., .lnal. Hiochem. 5, 426 (1963). (17) llead, J. A. K., Finger, K . F., Biochem. Pharmacol. 6 , 52 (1961). (18) Murphy, G . F., Sourkes, T. L., Rev. C a n . Biol.18, 379 (1959). (19) Shore, P. A , , Olin, J. S., J . Pharmacol. E r p t l . T h e r a p . 122, 295 (1958). (20) Smith, C. B., I b i d . , 142, 343 (1963). (21) Sourkeb, T. L., Murphy, G. F., Chavez, B., Zielinska, LI.] J . .Yeurochem. 8 , 109 (1961). (22) Towne, J. C., Fenster, E., Schaefer, T., Fed. Proc. 20, 343 (1961). (23) Towne, J. C., Fenster, E., Sherman, J., Schaefer, T., Ibid., 21, 420 (1962). (24) Udenfriend, S., Weissbach, H., Brodie, B. B., Method of Biochem. .Anal. 6 , 95 (1958). (25) Wiegand, 11. G . , Perry, J. E., Biochem. Pharmacol. 7, 181 (1961). RECEIVEDfor review October 9, 1964. Accepted February 18, 1965. Supported bv grants from the Xational Institutes ~ ~ . . of .~ ...~ Hea'lth, U. S. Public Health Service, 11H-03663, B-2453, and H-5239; American Heart Association 60G27; National Association of llental Health; The Council for Tobacco Research-U. S. A , : and American Legion Post Number 843, \-an S u y s , California. Reported in preliminary form ( I f ,22, 23).
Determination of Ruthenium a n d Osmium in O r e and MetaIIurgicaI Concentrates a n d in Osmiridium Completion of the Tin-Collection Scheme of Analysis for the Platinum G r o u p Metals G.
H. FAYE
Department o f Mines and Technical Surveys, Mineral Sciences Division, Mines Branch, Ottawa, Ontario, Canada Ruthenium and osmium are collected efficiently b y molten tin during the fusion step of fire assaying. These metals are isolated and separated from each other b y distillation procedures prior to their spectrophotometric estimation. The proposed methods have been applied successfully to the analysis of copper-nickel matte, a flotation concentrate, a precious metals concentrate, and a specimen of osmiridium. The manner in which the proposed methods can be combined with those for platinum palladium, rhodium, and iridium to produce a complete scheme of analysis i s indicated.
696
a
ANALYTICAL CHEMISTRY
T
HE DEVELOPMENT of a new analytical scheme for the determination of platinum and palladium (Or), rhodium (?)> iridium @), and gold (6) has been reported. In this scheme the 1)rccious metals are collected in molten tin when the sample material is fused at 1200' to 1250' C. with a flus containing stannic oside, sodium carbonate, silica, boras, and powdered coke. The resulting tin alloy is then treated by relatively sinil~le wet-chemical techniques to isolate and separate (8)the individual metal> prim to their determination by a1)l)rol)riatc spectrophotometric methods. The tin-collection schenit has tiern
applied successfully, in this laboratory, to the deterinination of one or more of the platinum metals and,,or gold in such diverse materials as silicate rocks, coppei~-nickel ores and concentrates, copper-nickel matte, meteorites of both the iron and stony types: and the minerals magnetite, chromite, and osmiridium. Some platiniferous materials such as certain of those listed above, also contain appreciable amounts of ruthenium and osmium. The deterinination of these elements is sometimes required in geochemical and mineralogical studies as n-ell a. in laboratoriec ahsociated n-it11 the production and refining of the
platinum met'als. Therefore, it is desirable to have a versatile scheme of analysis that can be used in a modestly equipped laboratorj,, for the determination of all six platinum metals and gold. This paper shows that the collection of ruthenium and osmium by tin during the fusion step of fire assaying is essentially complete and that satisfactory methods for the isolation of these elements from the tin alloy and their subsequent determination are available. This paper also indicates the manner in which the proposed methods ran be integrated with those for the other precious metals so that all can be determined on a single sample. Because of their convenience, radiochemical techniques involving the use of ruthenium-106 and osmium-191 were used to determine the distribution of ruthenium and osmium, respectively, in experiments on the fusion, distillation, and button-part,ing operations. The proposed methods have been applied to the determination of ruthenium in a copper-nickel flotation concentrate and in copper-nickel matte, to the determination of both ruthenium and osmium in a precious metals concentrate, and in the mineral osmiridium.
H Br KMnO4
APPARATUS AND SOLUTIONS
The apparatus used in the preparation of tin assay buttons has been described (5,6). Distillation Apparatus. T h e design of this apparatus is shown in Figure 1. Receiver B is a 250-ml., two-necked, round-bottomed flask which, during the ruthenium distillation, was fitted with a 250-ml. Glas-Col heating mantle. Receivers C a n d D are 125-ml. tall-form gas washing bottles with fritted cylinders a t the end of the inlet tubes. Each fritted cylinder was pierced to make a '/,s-inch diameter hole to permit free flow of gases through the apparatus. Standard Ruthenium and Osmium Solutions. These were oreoared seoarately by dissolving wiighed quantities of analyzed ammonium hexschloro-ruthenate (IV) or hexachloroosmate(1V) in a known volume of 1 S hydrochloric acid. The ruthenium and osmium contents of their respective salts were determined by weighing the metal residues that resulted when a weighed portion of each salt was roasted in hydrogen for 1 hour a t 650" C. and then cooled to room temperature in argon. Ruthenium- 106 and Osmium- 19 1 Tracer Solutions. These were prepared separately by dissolving (NH4)2Ru106C16 or (SH4)z051g1C1~ in 1.V hydrochloric acid so that the final solutions contained microcurie levels of activity per ml. The radioactive salts kyere obtained from the Commercial Products Division of the Atomic Energy of Canada Ltd., Ottawa, Ontario.
HBr
Figure 1 .
HBr
Distillation apparatus
EXPERIMENTAL AND RECOMMENDED PROCEDURE
Preparation of Tin Buttons. T h e procedure for preparing the buttons from synthetic mixtures (including those with ruthenium-106 and osmium-191) and from naturally plantiniferous materials was identical to that given previously (6-8). Analysis of Tin Buttons. The following procedures were used for the analysis of buttons prepared from synthetic changes salted with inactive ruthenium and/or osmium, as well as for those prepared from naturally platiniferous materials. Determination of Osmium. T h e granulated tin button (or aliquot thereof) was placed in a 500-ml. distillation flask. For every gram of alloy taken, approximately 5 ml. of 12.V hydrochloric acid was added. T h e flask was connected to the distillation apparatus (Figure 1) in which receivers B , C, a n d D contained 25, 40, a n d 15 ml. of concentrated hydrobromic acid, respectively. Receiver C' was cooled in an ice bath. Sitrogen gas was bubbled through the reaction misture a t the rate of 2 to 3 bubbles per second and then 307, hydrogen peroxide was forced through the delivery funnel in relatively small portions by 'pumping" with the
moistened heel of the palm while the stopcock was alternately opened and closed by the other hand. During the addition of peroxide, the gas pressure in the apparatus tended to vary; it was therefore necessary occasionally to increase the flow of nitrogen temporarily to prevent the receiver solutions from backing-up. After the tin alloy had been decomposed, a slight excess of hydrogen peroxide was added, heat was alq)lied, and the solution in the flask was evaporated until its temperature rose to 115-18" C. While maintaining the temperature in this range, approximately 15 ml. of 30y0 hydrogen peroxide !vas added in small portions in the manner described above. S e x t , 30 to 35 ml. of 12.V hydrochloric acid was added rapidly through the funnel and the distillation was continued until the temlierature again reached 115' C. T o ensure c8oml)lete distillation of osmium, the alternate addition of 15 to 30 ml. of peroxide and hydrochloric acid, respectively, was repeated two more times with the intervening evaporations necessary to bi,ing the temperature to a t least 115' C. hefore adding the peroside. After turning off the heat and alloiving the alq)aratus to cool somewhat, the receivers were disronnec-tcd ar1d their solutions combined in a 10O-ml. VOL. 37, N O . 6, M A Y 1965
697
mixture of hydrochloric acid and 30yG hydrogen peroxide to destroy bromides. NOTE. When the sample solution contains more than approximately 2 Ruthenium, pg. Osmium, pg. grams of base metals (udually copper) Taken Found Taken F a and it is to be analyzed subsequently for platinum, palladium, rhodium, or irid15 14 30 30 ium, it is recommended that the base 150 146 metals be removed by cation exchange mn m n.. ~ ( I , 7 , 11, 14) prior to the perchloric acid 300 295 distillation of ruthenium. 13y using 480 470 this approach, the subsequent task of 750 730 decomposing relatively large amounts of 6880a 6725 perchlorates is avoided. 29 30 48 47 (b) DISTILLATIONOF RUTHESICM. 30 30 235 235 The following procedure was applied to 145 149 48 50 samples from which osmium had been Charge did not contain added copper separated by distillation (with subseor nickel. quent volatilization of tin) or to samples that had been taken directly through the procedure given in ( a ) . The samplr was evaporated to dryness on the hot plate to drive off as much free beaker containing approximately 35 ml. hydrochloric acid as possible. After of concentrated hydrobromic acid and cooling the beaker, the residue was approximately 25 mg. of sodium chlotaken up in a small volume of water and ride. transferred to a 500-ml. distillation flask When the samples were known to conby washing with several small portions tain more than 300 pg. of osmium, the of water. The flask was connected to combined receivers were diluted to a the distillation assembly (Figure 1) in known volume with hydrobromic acid which receiver B contained a saturated and an aliquot was taken for analysis potassium permanganate solution, pre(below). pared by mixing 2 grams of solid perThe solution to be analyzed was manganate and 25 ml. of water; reevaporated first a t low heat to prevent ceivers C and D contained 40 and 15 ml. violent evolution of bromine; then it of concent'rated hydrobromic acid, rewas taken to incipient dryness (without spectively. Receiver C was cooled in baking) a t a more rapid rate. The an ice bath. While nitrogen was osmium content of the residue was bubbled through the apparatus a t the determined slJectrophotometrically with rate of 2 to 3 bubbles per second, about pyrogallol (si. 50 ml. of perchloric acid was added Determination of Ruthenium. ia) TREATMENT PRIORTO DISTILLATION. through the delivery funnel and heat was applied to both the distillation K h e n only ruthenium was to be deflask and the permanganate receiver termined, each button was granulated and parted in hydrochloric acid (5-8). with their separate heating elements. Heating was continued until the reThe resulting suspension was diluted to action mixture boiled and the white about 400 ml. with water, heated to 70' fumes disappeared (about 30 minutes), C., and then stirred with a motor-driven The permanganate receiver solution (espolyethylene-coated stirrer, while allsentially a trap for perchloric acid) was proximately 5 grams of powdered tin boiled vigorously until its volume was (-200 mesh) was sprinkled into the approximately 10 to 15 ml.; then the containing beaker to precipitate the heating mantle was shut off and reruthenium that had dissolved during the moved. parting operation. After stirring for The hydrobromic acid receiver s o h about 15 minutes, the beaker and contions were combined, treated with tents were again heated to 70°C. and a about 25 mg. of sodium chloride and second 5-gram portion of powdered tin evaporated just to moist salts prior to was added, as before, with an additional the spectrophotometric determination stirring period of 10 to 15 minutes. of ruthenium with p-nitrosodimethylThe insoluble matter produced in aniline ( 2 ) . these ol)erations, which contained all of When the ruthenium content was the platinum, palladium, rhodium, expected to be greater than 30 pg., the iridium, ruthenium, and gold in the solution was diluted to a known volume sample plus copper and excess tin with hydrobromic acid and an aliquot powder, was recovered by decantation was taken for the spectrophotometric and filtration and dissolved in a mixture determination. of hydrochloric acid and hydrogen perRadiochemical Techniques. Beoxide as in the methods for rhodium (7) cause of their simplicity and conand iridium ( 8 ) . venience, radiochemical techniques To volatilize tin, the beaker was were used to determine the distribuplaced in an aluminum evaporator on tion of ruthenium and osmium in the hot plate, treated with mixed hydromost of the experiments carried out chloric and hydrobromic acids (5) and during the development of the then hrated from above with an infrared methods proposed in this paper. heat lamp. The treatments with the The method of salting the flux with mixed halogen acids were repeated, with either ruthenium-106 or osmium-191 intervening evaporations until dry and until fumes were no longer visihle. and the preparation of standard soluThe final residue obtained in the above tions of known activity were similar to operations was treated with a 3 to 1 those described previously ( d j 8). In Table 1. Recovery of Osmium and Ruthenium from Salted Charges
5
698
e
ANALYTICAL CHEMISTRY
the present work radiometric measurements were made with a shielded 2 x 2 inch detector and appropriate circuitry. I n all radiochemical experiments a relatively large excess of inactive ruthenium and/or osmium was present as carrier. EXPERIMENTS A N D RESULTS
Preliminary Experiments on Button Decomposition. Ruthenium and osmium can be distilled completely during the decomposition of ironcopper-nickel alloys in boiling perchloric acid ( I O ) . I t was hoped that this approach might also be suitable for the recovery of the two metals in the present work; therefore it was tested on tin buttons prepared from charges that had been salted with ruthenium-106 or osmium-191 and with various amounts of copper and nickel (up to 2 grams). Radiometric analysis of the perchloric acid still-residues showed that from 20 to 707, of either ruthenium or osmium remained nonvolatile even after prolonged boiling. d white tin compound separated out during early stages of the operation and it was learned in sub sequent experiments that this material trapped much of the osmium and ruthenium. A further disagreeable feature of the perchloric acid attack was that, even with cautious heating, the reaction with the tin alloy sometimes tended to become violent. Behavior of Ruthenium and, Osmium during Treatment with Hydrochloric Acid-Hydrogen Peroxide Mixtures. T h e results of the above experiments suggested the necessity of removing tin from the sample material before distillation of ruthenium a n d / o r osmium. Because the volatilization of stannic tin from a hydrochloric-hydrobromic acid mixture has been used successfully in previous work ( 5 , 8 ) . it was decided to test this process on solutions containing tin and osmium or ruthenium. However, because it was expected that in practice a mixture of hydrochloric acid and hydrogen peroxide would be used to oxidize tin to the stannic condition, it was necessary first to determine the effect of this oxidizing mixture on solutions of ruthenium and osmium. Experiments showed that ruthenium remained nonvolatile when solutions of hexachlororuthenate or osmate were evaporated to dryness in an open beaker and the residues of salts mere boiled with several 10-ml. portions of a 2 to 1 mixture of hydrochloric acid and 30% hydrogen peroxide; hon ever, depending upon the conditions and the number of treatments, a substantial proportion of the osmium was volatilized. Surprisingly, in four separate trials with 243 p g . of osmium, after a single treatment with the oxidiz-
ing mixture, only 5% of the osmium was volatilized. I n other tests however, as much as 607, was volatilized after three treatments with intervening evaporations to dryness. Behavior of Ruthenium and Osmium during Volatilization of Tin. \Yhen synthetic solutions, containing stannic tin and inactive ruthenium or osmium, were taken through the tin volatilization procedure in open beakers, rut,henium remained nonvolatile while most of the osmium was lost by volatilization. T o avoid contaminating the laboratory a t mosphere, tracers were not used in these tests. Button Decomposition and Distillation of Osmium with Hydrochloric Acid-Peroxide Mixtures. I n the work described above, the extent of osmium volatilization [present initially as h e x a c h l o r ~ - o s m a t e ( I \ ~ seemed )] to depend, in p a r t , on the temperature to which the solution was heated during treatment with the hydrochloric acidhydrogen peroside mixture and during the intervening evaporations between such treatments. However, because of the nature of the solutions, the maximum temperature attainable was approximately 105' C.; this was probably too low for the complet'e conversion of osmium to the volatile tet,roxide (13 ) . Because solutions obtained by dissolving a typical tin button in a mixture of hydrochloric acid and peroxide contain a substantial amount of dissolved tin, it was expected that they should have a relatively high boiling point after being concentrated by evaporation. Therefore, it was decided to investigate the possibility of recovering osmium directly by distillation from such solutions. Accordingly, a number of buttons, weighing about 20 grams each, were prepared from charges salted with osmium-191. These were granulated and then treated in the distillation appamtus in a manner similar to that given above under the procedure for the Determination of Osmium. The results of these tests signified that when the stannic chloride solution of the button was concentrated by evaporation (in the distillation apparatus) and treated by t,he repeated dropwise additions of hydrogen peroxide, u-hcn the temperature of the solution was in the range 113-18" C., complete volatilization of osmium could be achieved. Radiometric measurements in these experiments showed that a t least 98% of the added osmium-191 was recovered in the distillate and also. that the collection of osmium during the fusion operation was essentially coinple t r Itadioehemical experiment,s with ruthenium-106 showed that under the ponditions used for the osmium dis-
tillation, ruthenium was not volatilized; therefore, a complete separation of osmium and ruthenium can be effected. Perchloric Acid Distillation of Ruthenium. A number of synthetic tin buttons containing ruthenium-106 mere each taken through the hydrochloric acid-hydrogen peroxide decomposition and osmium distillation procedure. Tin was volatilized from the distillation residues and the ruthenium was distilled from a boiling perchloric acid medium as in the Experimental and Recommended Procedure. Radiometric analysis of the distillates and still-residues indicated complete recovery of ruthenium by distillation. I n these esperiments, an average over-all recovery of approsimately 98% was obtained; and this is also evidence of the efficient collection of ruthenium by tin during the fusion operation. Recovery of Ruthenium from "Parting-Acid" Solution with Tin Powder. M a n y platiniferous materials, such as ores and concentrates of the Sudbury district of Ontario, contain little or no osmium. Therefore, it was desired for reasons of convenience, to have a procedure t h a t would bypass the hydrochloric acid-hydrogen peroxide decomposition step in the proposed scheme of analysis when osmium was not to be determined. I n previous work on the tin-collection scheme of analysis, the assay buttons were parted in hot concentrated hydrochloric acid; any ' platinum nietals that dissolved were recovered easily by treating the parting-acid with tin powder (7,9). Because this method is relatively fast and eliminates most of the nickel from the button material, it was tested for use in the present work. I t was known that nickel and copper in the assay button tend to increase the solubility of rhodium ( 7 ) and iridium (9) during parting. Therefore, several buttons were prepared from charges that' contained 1 assay ton of roasted copper-nickel flotation concentrate (5) and had been salted with ruthenium106. Radiometric measurements showed that when these buttons were decomposed in hot hydrochloric acid, approximately 50% of the ruthenium dissolved. Whereas rhodium and iridium can be recovered readily from the diluted parting-acid a t room teniperature with tin powder ( 7 , 9), experiments showed that it was necessary to heat the solution to approximately 70" C. to ensure complete recovery of ruthenium. Loss of Ruthenium and Osmium to Slag and Crucible during Fusion. Radiometric analysis of the slags f r o m , and the crucibles used in, certain of the esperiments described
above, showed t h a t the average loss of ruthenium and osmium to the slag was approximately 0.2 and 0.87,. respectively; the loss to the crucible was negligible in both cases. Chemical Analysis of Buttons Obtained from Synthetic Charges. -41though radiochemical experimerlts had shown that the proposed fusion process and wet chemical separations were satisfactory, it was also necessary to test these by using purely chemical methods for the analysis of the final osmium and ruthenium fractions. rlcc~ordingly,a series of buttons was prepared from charges containing ruthenium and,'or osmium and 0.5 gram each of nickel and copper. The base metals were added to siniulate buttons produced during the anal many types of platiniferous materials. The tin assay buttons were analyzed for ruthenium and osmium in the manner described under Experimental and Recommended Procedure and the results are given in Table I. I t is evident from Table I that recovery of both ruthenium and osmium from synthetic samples, by a combination of the proposed fire assay and wetchemical methods, is nearly complete. The effectiveness of the new method for the selective distillation of osmium in the presence of ruthenium is also made evident, A P P L I C A T I O N OF P R O P O S E D M E T H O D S
Table I1 gives the results obtained when the proposed methods were applied to the determination of both ruthenium and osmium in a specimen of the mineral osmiridium, in a irecious nietals concentrate, and also to ruthenium only in copper-nickel matte and a flotation concentrate. The platinum, palladium, rhodium, and iridium contents of osmiridium from the same source as that used in this work have been reported previously (9). The precious metals concentrate, produced in an electrolytic refining process, was reported by the donor (Falconbridge Sickel Mines Limited, Thornhill, Ontario) to contain approximately 20% silver and 16% combined platinum-group metals. For comparison purposes, the donor's ruthenium value for this material, obtained by a perchloric acid distillation procedure, is given in Table 11. I n the present work, the precious metals concentrate was fused directly because it was known that, when such material is roasted in air, osmium is lost by volatilization ( 1 2 ) . The platinum, palladium, rhodium, iridium, gold, and base-metals contents of the copper-nickel matte and flotation concentrate have heen given in previous papers on the tin-collection scheme of (6-7> 9 ) . The average ruVOL. 37,
NO. 6,
M A Y 1965
e
699
1
1
P r e - t r e a t Sample i f Necessary Leach a n d / o r Roast
+ Fuse w i t h SnO,
Bearing Flux
1
When Os t o be Determined
When Os not to be Determined
Tin Button (Granulated)
Stiil residue
,
I
I
I
T i n Powder a t 70°C.
I
Dissolve in HCI t ti202
Pt, Pd, Rh, lr, Au, Cu Excess Tin Powder
1
I Perchloric Acid D i s t i l l a t i o n
4
- _ _* -
Evaporate S t i i l Residue
'r'
I Drlve off HC104
____
4
Figure 2.
1= 2a 3b 4*
5. 6c
~~
Copper-nickel Copper-nickel Copper-nickel Copper-nickel Copper-nickel Copper-nickel
matte matte matte matte matte matte
Sample wt. 0 . 5 assay ton
0 , s assay ton
1 assay ton 1 assay ton 4 grams 4 grams
Av. 7= 8c 9C
SnCi,
Determination of Ruthenium and Osmium in Various Materials
Kature of sample
Flotation conc. Flotation conc. Flotation conc.
1 assay ton 1 assay ton 1 assay ton
Av.
Found, troy oz./ton Independent Proposed method laboratory Ru OS Ru 0.044 0.043 0.040 0.042 0.045 0.042 0.043 0,009 0,009 0.007 0.008
0.042
Per cent 10 11 12
Precious metals conc. Precious metals conc. Precious metals conc.
1 gram 1 gram 1 gram
13 14 15
Osmiridium Osmiridium Osmiridium
9 . 7 2 mg. 8 . 3 0 mg
8.75 mg
4.63 4 . .58 4.71 Av. 4 . 6 4 14.1 14.5 15.2 Av. 1 4 . 6
0.038 0.038 0,038 0.038 35.8 38.0 36.4 36.7
4.75
a Samples were leached in 12A' hydrochloric acid, the leach residue was then dissolved in HC1-H202 mixture and perchloric acid distillation was performed. Samples were leached in 12A' hydrochloric acid and leach residue was roasted before fusion. In Tests 10 to 15, samples were fused directly, c Samples fused directly after roasting. no pretreatment.
700 *
ANALYTICAL CHEMISTRY
Remove Base M e t a l s by Exchan(le
p-nltroso-
SnBrp
SnCle
dimethylanaline
in HBr
in HBr
Flow sheet for new scheme of analysis for precious metals
Test XO.
__c
7c 0- tolidine
II.
Reject -
Extraction of Au as Bromo-Aurate
p-nitrosodimethylaniline
Table
+
When Ru not to be determined
with Aqua Regia . _ _ _ _c_ Treat _ Convert to Chlorides f
D e c a n t and F i l t e r
+
thenium value of the matte obtained in the donor's laboratory is also given in Table 11. It is to be noted in Table I1 that the matte may be leached to remove the bulk of the base metals and then roasted prior to analysis, without losing ruthenium. The latter finding is important for it suggests that other rutheniumbearing materials such as the flotation concentrate may also be roasted without volatilizing ruthenium. Tests 1 and 2 show that ruthenium can be determined in the matte by purely wet-chemical methods. HOKever, when other platinum metals are also to be determined on the same sample the fusion decomposition may be preferable. Table 11 also shows that the ruthenium results obtained for the matte and precious metals concentrate are essentially in agreement with those obtained in the Falconbridge laboratory. From prior information regarding the coimei-nickel matte. it was assumed .. that its osmium content was negligible. However, a t the conclusion of the work described in this I,al,er and when the SUPP1J' O f the matte nearly exhausted, a single determination on the unroasted hydrochloric acid leach res-
idue from a 2-assay-ton sample indicated the presence of 0.01 troy oz./ton of osmium. I t is realized that more reproducible results probably could have been obtained for ruthenium and osmium in osmiridium, and for ruthenium in the precious metals concentrate, by gravimetric analysis of the final fractions rather than by the more convenient spectrophotometric methods which involved relatively large dilution factors. However, the results given show clearly the suitability of the proposed methods when applied to those sample materials. INTEGRATION O F PROPOSED METHODS I N T O A N A L Y T I C A L S C H E M E F O R SIX P L A T I N U M METALS
Csually, when ruthenium and/or osmium are to be determined in materials such as ore concentrates, mineral specimens, meteorites, or metallurgical products, it is also desirable to determine the other four metals of the
platinum group. Consequently, it is necessary to have a flexible scheme of analysis that will permit the determination of all six metals on a single sample, but a t the same time permit unnecessary operations to be readily bypassed when only partial analysis is required. Such a scheme is presented in Figure 2 in the form of a flow-sheet in which it is shown how the proposed methods for ruthenium and osmium can be combined with those previously reported for platinum and palladium ( 5 ) , gold ( 6 ) ,rhodium ( 7 ), and iridium (9). ACKNOWLEDGMENT
The author acknowledges the assistance of P. E. Moloughney in certain aspects of the work described in this paper. Thanks are due to Falconbridge Nickel Mines, Ltd., for supplying the copper-nickel matte, flotation concentrate, and the precious metals concentrate, and also to Johnson, Matthey
and Co., Ltd. (Toronto), for supplying the osmiridium used in the present work. LITERATURE CITED
(1) Coburn, H. G., Beamish, F. E., ANAL.CHEM.28, 1297 (1956). (2) Currah, J. E., Fischel, A,, McBryde, W.A . E., Beamish, F. E., Ibid., 24, 1980 (1952). (3) Faye, G . H., Ibid., 37, 259 (1965). (4) Faye, G. H., Inman, W. R., Ibid., 31, 1072 (1959). (5) Ibid., 33, 278 (1961). (6) Ibid.. D. 1914. ( 7 j Ibid.; '34,972 (1962). (8)Ibid., 35, 985 (1963). (9) Faye, G. H., Inman, W. R., Lloloiighney, P. E., Ibid., 36, 366 (1964). (10) Kavanayh, J. AI., Beamish, F. E., Zbid , 32, 490 (1960). (11) Marks, A. G., Beamish, F. E., Ibid., 30, 1464 (1958). (12) Van Loon, J. C., Beamish, F. E., Ibid., 36, 872 (1964). (13) Westland, A . D., Beamish, F. E., Microchim. Acta 5 , 625 (1'357). (14) Zachariasen. H.. Beamish. F. E.. ASAI,. CHEM.34, 965 (1962). ' RECEIVED for review January 18, 1965. Accepted LIarch 1, 1965.
Determination of SmaII Amounts of Nitrite by Solvent Extraction and Spectrophotometry ANTHONY FORIS and THOMAS R. SWEET Department of Chemistry, McPherson Chemical laboratory, The Ohio State University, Columbus, Ohio The reactions between 8-aminoquinoline and nitrous acid and quinoline diazonium ion and 8-aminoquinoline have been investigated. Reaction parameters for both the diazotization and the coupling processes have been determined. A method for the determination of small amounts of nitrite is proposed which is based on the above reaction sequence and employs solvent extraction and spectrophotometry. The sensitivity of the method, expressed as the weight of nitrite resulting in an absorbance of 0.010 a t 465 mp in a 1-cm. cell, is 0.151 pg. This corresponds to a sensitivity of 0.0038 p.p.m. if a 40-ml. sample of unknown is used.
available for the detection and determination of nitrite and nitrite precursors have recently been reviewed by Kolthoff and Elving (3) and Sawicki, I'faff, and Stanley ( 4 ) . I n other publications Sawicki compared the merits of 36 new methods ( 5 ) and discussed a series of autocatalytic methods for the determination of nitrite through free radical chromogens (6). The reaction sequence employed in the present method consists of two steps. The first step (I) involves the
condensation of the amino group with nitrous acid.
+
HNOz
+ H@ -+
"2
+ 2Hz0
(I)
111
N
I n the second step (11), the diazonium ion couples with excess 8-aminoquinoline to yield a highly colored azo dye.
ETHODS
Elemental analysis of the isolated reaction product yielded results that agreed well with the theoretical values (found: C, 72.03%; H , 4.43%; K, 23.29% ; calculated : C, 72.22%; H, 4.38y0; 5 , 23.40y0). The compound decomposed at 183" C.
432 I 0
EXPERIMENTAL
Apparatus. T h e absorption curves shown in Figure 1 were made on a Cary Model 14 recording spectrophotometer. All other absorbance measurements were made with a D U spect ro p ho t o m e t e r Be c kman equipped with a photomultiplier a t tachment. The absorbance of all solutions was measured in Beckman 1-cm. quartzwindow absorption cells fitted Kith ground glass stoppers. h l l pH measurements were made with a Beckman Model G pH meter with general purpose glass electrodes and fiber junction calomel reference electrodes, or with Beckman combination electrodes, S o . 39183. Reagents. 8 - AMINOQUINOLINE REAGEKT SOLUTIONS.The reagent solution for procedure I mas prepared by dissolving 2.00 grams of 8-aminoquinoline (Eastman Organic Chemicals No. 4033) in 5 ml. of concentrated hydrochloric acid and a minimum of water. The solution was made ul) to 100 ml. with demineralized double-distilled water. For procedure 11, a 2% solution of 8-aminoquinoline was prcpared which also contained 50 ml. of glacial acetic acid per 100 ml. of solution. STANDARD
SITRITE
SOLUTIO
stock solution was prepared by dissolving 1.500 grams of reagent grade S a S O , VOL. 37, NO. 6, M A Y 1965
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