ANALYTICAL CHEMISTRY C'hibiiall, -X.C . , Kee,. kl. A
., and Williarn~,L. F., Biochen~.J . ,
3 7 , 3 5 4 (1943).
Clark, E. P., J.Assoc. Oficial A g r . Chem., 24, 641 (1941). Dalrymple, R. S., and King, G. B., IND.ENG.CHEM.,hv41 ED.,1 7 , 4 0 3 (1945). Dartington Hall Trustees, Laboratory Staff, J . Soc. Chem. Ind.. 58, 79 (1939). Gallant, D. L., and Toennies, G., unpublished data. Hoffman. W. 8.. and Osgood, B.. J . Lab. Clin. Mcd.. 25, 856 (1940).
Holiday, E. K., Biochem. J . , 30, 1795 (1936). Jonnard, R., ISD.ENG.CHEM.. A N ~ LED.. . 17. 246 (1945). Koch. F. C . arid NrMeekin, T. L., J . Am. Chem. Soc.. 46, 2066 (1924).
Liridner, R. C . , and Harley, C. P., Science, 96, 565 (1942). Miller, G. L., J . Ezptl. M e d . , 79, 173 (1944). Miller, L.,and Houghton, J . A, J.&oZ. Chern., 159, 373 (19451 Sanigar, E. B., and Allen, A. J., J . Lab. Clin. M e d . , 2 1 , 9 6 9 (19351936).
Shirley, R. L., and Becker, W. W., IND.ENG.CHEM.,ANAL.ED. 17,437 (1945).
Van Slyke, D. D., Hiller, A , arid Dillon, R. T., J . Biol. Chem. 146, 137 (1942).
T'ickeri. H. B.. and Wiriternita. J. K.. Ihid., 156, 311 (1944). West, E. S.,and Brandon. A . L.. Isn. ENG.CHEM.,ANAL.E u 4 , 3 1 4 (1932). RECEIVEDSeptember 17, 1947.
t i d e d b> funds In memory of Ruth C
.Joyce.
Microdetermination of Tellurium V R. H.
D E M E I O ' , Harvard School of Public Health. Boston, .Mass.
To determine tellurium in air dust, the sample is dissolved with the aid of sulfuric and nitric acids and hydrogen peroxide, and the tellurium is precipitated by boiling with hydrazine dihydrochloride and stannous chloride. The precipitated tellurium is dissolved in warm 1 to 1 nitric acid, the solution evaporated to dryness, the residue taken up in concentrated hydrochloric acid, and tellurium precipitated again with stannous chloride in presence of gum arabic. The degree of light absorption produced by the suspension is determined with the Klett-Summerson photoelectric colorimeter using light filter No. 42. The method allows the determination of 5 t o 140 micrograms of tellurium with an error of 10%.
I
T IS to Lenher that we owe a great deal of our knowledge con-
cerning the chemical behavior of tellurium. Plfost of the macromethods for its determination in use a t present are either his methods or modifications of them ( I ) . The few niicromethods developed include the colorimetrir cechnique of Volkov (4, that of Kronenberg and Setterlind ( 2 ) for 50 to 700 micrograms of tellurium, applied to air dust analysis in iron foundries, and the method used by Steinberg, Massari, Miner, and Rink (3)for 5 to 50 micrograms used in the determination of tellurium in air dust samples and urine. All three method\ are based on the reduction to elementary tellurium. This paper deals with the application of the same principle to the determination of minute quantities of the element with the IISP (if t hr Klrtt-Summerson photoelectric colorimeter. REAGENTS
Concentrated hydrochloric acid. Distilled water, particle-free, filtered through sintered glass funnels F. A 5% solution of gum arabic, freed by centrifugation from suspended particles. A 1 0 9 solution of stannous chloride, prepared by addin'g 1 ml. of concentrated hydrochloric acid and 10 ml. of distilled water for each gram of stannous chloride, and centrifuging to free it from turbidity. A 15% solution of hydrazine dihydrochloride. Standard tellurium solution, prepared by dissolving 50 mg. of elementary tellurium in warm 1 to 1 nitric acid and evaporating to dryness. The residue is dissolved in a few drops of 10% sodium hydroxide and brought to 500 ml. with filtered distilled water (1 ml. = 100 micrograms of tellurium). This solution will be stable for six, or probably more, months. 4 standard solution prepared by dissolving the residue of the nitric acid solution in diluted hydrochloric acid was less stable; in time a white precipitate, probably tellurium dioxide, settled out. PRELIMIKARY TREATMENT OF SAMPLE
Steiiiherg and co-workers (3) and Kronenberg and Setterlitid i d ) have developed methods for air sampling in iron foundries.
____ ' Present
I
address, Department of Experimental Medicine, The Jefferson Medml Colleae, Philadelphia Pa.
Thr authors have analyzrd ai1 ~ a n i p l efrom ~ a selenium and tellurium plant, The atmospheric dust was c.ollec.1edon filter paper by means of a filter paper sampler. Whatman S o . 52 paper was used and air drawn through the paper at abmeasured rate in the range from 30 to 40 liters per minute. The rate of flou was measured by the use of an orifice a t the intake and a water manometer and calibrated with a standard rotameter and gas meter. A uniform procedure for analysis cannot be used, as the concentration of tellurium in air varies in different parts of the plant. The volume of air collected varied from 400 to 3000 liters and tellurium per cubic meter of air varied from 0 to 12 mg. Consequently, an appropriate aliquot had to be used for every sample. The dust sample was treated with 5 ml. of concentrated sulfuric acid, concentrated nitric acid, and 30% hydrogen peroxide, or with concentrated hydrochloric acid and potassium chlorate, accwrding to Scott (1). In the presence of selenium, this element should he separated first by volatili7ition according to Idenher and Smith ( I ) . ISOLATION hND DETERVINATION OF TELLURIUM
After the above treatment, 50 ml. of distilled water followed by 5Onii. of approximately 3;V hydrochloric acid were added, and the residue was brought into solution if neressary, by heating. After addition of 6 ml. of 1570 hydrazine dihydrochloride and 10 ml. of 10% stannous chloride, the solution was boiled for 15 minutes. In this manner complete precipitation of tellurium was achieved. The tellurium precipitate was collected in a Selas
Table I. Te Added, Micrograms 10 20
Recovery of Tellurium Te Found, Micrograms
%
- 12 -- 10 10
8.8
18
30
40 50
27 39 47
100
102
120 140
Error,
110 135
-2.5 -6
'
fi.3 -3.6
V O L U M E 20, NO. 5, M A Y 1 9 4 8 porcelain crucible, with the u>e of suctioii. It nab \+askled first with a few milliliters of approximately 3 S hydrochloric acid to %voidprecipitation of basic tin salt. and then with hot distilled water until i t was free from chloride. During filtering, the precipitate was kept always covered by the solution in order to avoid nossible oxidation and, as a con\equence, solution of the tellurium The crucible was placed on a nra suction flask and the beaker, i n R hich the precipitation had bpen carried out, was n ashed with 3 few milliliters of warm 1 to 1 nitric acid which was then trans;erred into the crucible. More warm 1 to 1 nitric acid was added t o the crucible until tellurium was complf~telydissolved. The tellurium solution was transferred from the suction flask to a 50ml. beaker and evaporated to dryness on a hot plate. The residue was taken up with 3 ml. of concentrated hydrochlorir acid, transferred to a graduated test tube of 1.2-cm. diameter, brought to a volume of 8 ml. with filterd distilled water, and mixed by stirring 'rith a glass rod. One milliliter of 10% stannoui chloride was added to this solution with immediate and vieorow stirring and this was followed by the addition of 1 ml. of 5% gum arabic, with Pqually vigorous and immediate stirring. This concentration of min arabic stabilizes the tellurium suspension for about 6 hours. Deviations from this standardized technique led to irregular results. Obviously the rfficiency oi iiiising affected the particle iizes in the tellurium suspension. By adding stannous chloride before the gum arahic is added, a higher light absorption and a higher sensitivity are attained. Tellurate is not reduced by stanwus chloride under the conditions of this method. The absorption was compared in the Klett-Summerson photoelectric colorimeter, using light filter No. 42, with that of a blank. The concentration may be read off a graph or computed by mulmicrograms of tellurium ___, which riplying the reading by the factor reading i i i this case yielded 0.346. Graph and factor are readily obtained :rom a series of controls. Plotting of the amount of tellurium, be~
489 tween 5 and 140 micrograms, against the colorimeter reading gave a straight line, which shows that Beer's law is satisfied. Tahle I gives a few of the results obtained and shows that tvlluriurn can be determined with an error of * loyo. Application of the method to the analysis of urine was atwmpted. Urine blanks show ab3orption wit,h the filter employed. This difficulty may be overcome by removal of t,he tellurium by centrifuging after the colorimetric value has been determined and subtra,cting the reading obtained with the centrifugate. With the same light filter ( S o . 421 in the Klettkhimerson photoelectric colorimet,er, one may use the method also for the determinat,ion of selenium. ACKNOWLEDGMENT
T h r author is indebted to John ?;. dbersold for t,he description of the air-sampling kchnique. LITERATURE CITED !1) Furman, N. H., Ed., ''Scott's Standard Methods of Chemical Analysis," Vol. 1. pp. 778--93! Kew Tork, D. Yan Xostrand
Co., 1939. (2) Kronenberg, 31.H., and Setterlind, 1.S . ,"Determination of Tellurium in Air Collected in Ferrous Foundries," State of Illinois Dept. Public Health, Division of Industrial Hygiene. Laboratorj- Manual, September 1942. (3) St,einberg,H. H., Massari, 9. C., Miner. A . C., and Kink, Ti.. .1. Ind. Hyg. Toricol., 24, 183 (19421. (4jVolkov, S. T., Zavodskaya Lab., 5,1429 (1938). RECEIVED M a y 2, 1947.
Direct-Reading Contact Scale for Analysis of X-Ray Spectrometer Charts WILFRID R. FOSTER, Ceramic Division, Champion Spark P l u g Company, Detroit 1 1 . Mich.
HE recording x-ray spevtronieter (Sorelco Geiger-counter 'x-ray spectrometer) which hah recently become commercial15 .tvailable is proving a boon to industrial research and control iahoratories because of the speed with which it yields results. By its use a complete diffraction pattern can ordinarily be ob+ained in a small fraction of the time required with the usual diffraction-camera equipment. The pattern so obtained i6 analogous t o the microphotometer trace of the photographic pattern, but is superior in sensitivity and resolution. Proper interpretation of such a spectrometer pattern involves, of rourse, the determination of the d-value (interplanar spacing) corre.yonding to each peak, the evaluation of the relative intensities of khr peaks, and a check of these data aga2ini.t the A.S.T.hl Bard file of x-ray diffraction data. In an industrial testing lahoratory, M here the spectrometer riiay he in continuous service, the analvsis of the steadil: accumuiatirig charts can consume a considerable amount of time. To jhvkte the tediousnestsof repeated solution of the Bragg equation by actual calculation. it has become standard practice to use tabulated data ( 2 ) relating Bragg angle to d-value for the par+ d a r target material used. This t r 4 t s in a distinct saving of time. However, errors in estimating the value of the Bragg anpk or in reading and interpolating the tahulatrd data are not infrequent. .\ time-saving and accurac? -inc>reabingdevire is a combined kwo-theta and d-value scale which. when appropriately aligned with the spectrometer pattern, alloas one t o read directly the d-values of the peaks. Two-theta, or tn-ice the Bragg angle, is Phosen as the unii of meawrcnirnt of this scale, hecause the
angular motion of the Geiger counter is eo measured. Since for most mork the speed of the Geiger counter is iuch as to give a -15-inch chart tor 90" of two-theta, the scale is made up on the hasis of 2"of txo-theta per inch. Since for mobt work the coppertarget x-ray tube is employed, the scale is made up from the data of the appropriate tables for copper K a radiation. The scale may be constructed In t a o section
