(0.3V Q . ~ e mr ' !
1 60
1
COL:EYTRA-ION
OF C n L C I u M p9 Per ml
Figure 3. Effect o f calcium on emission intensity of strontium Wavelength, 460.7 rn9
Since the emission intensity of strontium rcmains constant over a very wide range of calcium concentration, i t has become standard procedure to adjust the calcium concentration of the solution aspirated to 200 pg. per ml. I n addition to being an excellent radiation buffer, the calcium also minimizes the adverse effects of both cations and anions. Strontium Impurity in ReagentGrade Calcium Compounds. Xhile developing this method whereby the radiation buffer effect of calcium on strontium is used, several compounds of calcium were analyzed for strontium. -111 the reagent-grade calcium compounds tested contained strontium (see Table 111).
Applications. The method has been used satisfactorily to determine strontium in raw waters, clamshells, chicken bones, and two National Bureau of Standards (NBS)standard samples of limestone. The results are shown in Table IV; they give some indication of the accuracy and precision that can be expected from the method. For NBS sample la, the value obtained agrees with that reported by Wade and Seim (14), n-ho used a separation procedure. For KBS sample 88, the value obtained agrees with the value 0.005 wt. % reported by Diamond ( 2 ), n-ho used a standard-addition technique. Strontium in marine organisms has also been determined satisfactorily by this method. ACKNOWLEDGMENT
The authors thank S.R. Koirtyohann for calling their attention to the method for the preparation of strontium-free calcium. They also thank D. J. Selson for his interest in this n-ork and for urnishing test samples. LITERATURE CITED
1) Dean, J. A., "Flame Photometry," p 203-209, McGraw-Hill, Yew Yor!,
.
1960.
( 2 ) Diamond, J. J., -4x.4~.CHEY.27, 913
(1955). (3) Farmer, V. C., Thesis, University of Aberdeen, Scotland, 1946. (4) Hinsvark, 0. N., TT-ittwer, S. H., Sell, H. M.,- 4 n i . k ~ .CHEV.2 5 , 3 2 0 (1953). ( 5 ) Horr, C. A., U. S. Geol. Survey, Jvater Supply Paper S o . 1 4 9 6 4 , 1959. ( 6 ) Huldt, L., =Irkzv J l a 2 . . i s l ~ o n .Fyszk, B31, 1, (1944). 1 7 ) IiPller. AI. T.. Fisher. D. J.. Jones. ' H . C. ".IXU, CHEV. 31, 178 ( 1 ~ 4 ) .' (8) Alitchell, It. L., lechniral Communication S o . 44, pp. 129-30. Commonwealth Bureau of Soil Science, Ilaruenden, England, 1918. (9) Odum, H. T., Institute o j Illari7w Sci. 4, 54 (1957). (10) Odum, H. T., Ph.D. thesis, Yale University, Kew Haven, Conn., 1950. (11) Rains, T. C., Zittel, H. E., unpuhlished data, Oak Ridge Sational Lnboratory, Oak Ridge, Tenn., March 1961. (12) Sowden, E. IT,, Stitch, S. I K o p i i a , T., Kawasaki, N., Buli. Cheu!. SOC.Japan 29, 683 (1956). (14) Wade, 11. A., Seim, 11. J.. ANAL. C H E Y . 33, 793 (1961).
RECEIVEDfor review January 26, 1962. Accepted April 2, 1962. Prcscnted at Combined Southnest and Southeast Regional Meetings of .ICs,S e w Orleans, La., Dec. 7-9, 1961. Oak Ridge Sational Laboratory is operated by Vnion Carbide Corp. for the Atomic Energy Commiwion.
II.
Spectrochemical Determination of Beryllium in Air-Borne Dust at the Microgram a n d Submicrogram Levels R. L. O'NEIL AC Spark Division, General Motors Corp., Flint, Mich.
b A spectrographic procedure for the determination of beryllium in airborne dust has been developed. Inplant sampling is done with a portable high volume air sampler. Samples are burned with the direct curren arc in a controlled atmosphere o f carbon dioxide gas using lutetium as the in:ernal standard. Precision in the 2- to 50-119. range i s from +0.4 to *4 pg. a t the 95% confidence level. The method is sensitive to 1 X 10-6yo b y weight of beryllium or 1 X 1 0-4 pg. of beryllium in the electrode.
A
DUST containing beryllium constitutes a potential health hazard in laboratories and working areas when used in manufacturing processes. The maximum allowable concentration has been covered by Hodge in a memoIR-BORKE
randum on safe handling practices for beryllium (6). Methods of analysis for beryllium have received Ivide attention in recent years, and a number of chemical and spectrographic procedures have been reported. Refinement of colorimetric methods has continued, and the fluorimetric method with morin has been estensively investigated (9, 16, 17). Several highly sensitive spectrographic procedures for beryllium have been developed (2-4, 10, I S ) . The air dust in our working area contains calcined aluminum oxide, which is not amenable to acid attack. For this reason and because it was believed t h a t a direct spectrographic procedure R-ould give the required sensitivity to satisfy initial safety requirements, the work reported in this paper was undertaken. Although no attempt has been made to
extend the method to materials other than those of interest in the ceramics field, i t is felt that the method should be applicable to other materials as well. S t a l h o o d in 1954 (18) described a simple attachment which could be used with the d.c. arc to eliminate cyanogen interference and make avai1:ible for measurement lines not ordinarily used. Joensuu ( 7 ) substituted carbon dioxide for air in the determination of the rare earths, scandium, and thorium and reported escellent agreement with chemical values. Shaiv (15) tried carbon dioxide, argon, and mixtures of argon and oxygen as well. Although these authors tended to emphasize the suppression of the cyanogen band structure, additional ailvantages in the use of a controlled atmosphere have been noted ( 1 . 2 ) . T'olutilization behavior of a large number of eleVOL 34, NO. 7, JUNE 1962
781
man No. 41 filter papers, sealed on removal from the sampler in individual cellophane envelopes, marked, and sent to the spectrographic laboratory for analysis. Preliminary Experimental Work. Samples of the air-borne dust were collected and analyzed to obtain the concentration levels of the major constituents. Alumina comprises the bulk of the particulate matter present. The average composition of six samples collected a t 1-hour intervals during a working period of 8 hours is given in Table I.
100:
10:
/
0
f
P P
in 81 I:
I
-06
-04
-02
m
I
61.
8OL
Table I. Average Composition of Six Air-borne Dust Samples
, (
P P
0
+02
to4
+
LOG 8,. I 1 3131 07 Lu 2969 82
Figure 1 . Analytical curve for beryllium
ments with dissimilar properties is very similar in the controlled atmosphere. Moving plate studies were made for 25 elements including beryllium and lutetium and their volatilization curves compared. Both beryllium and lutetium volatilize a t nearly the same rate and persist until the burn-off of the sample is complete. This behavior produces a smoother burn during excitation, a fact attributed, in part a t least, to the temperature gradient effected by the moving gas stream which cools the lower portion of the sample while the uppermost part burns. Interelement effects tend to be minimized, a condition which can be further improved by first fusing the sample with lithium borate as reported by Tingle and Matocha (19), or with sodium metaborate as recommended by Joensuu and Suhr ( 8 ) . Enhancement effects in a gaseous atmosphere appear to depend on the gas used. I n the arc in carbon dioxide the alkaline earths show considerable enhancement; other elements, viz., tin, zinc, etc., are depressed. Beryllium does not appear to be enhanced. However, the spectral background is greatly reduced in the controlled atmosphere and the improved line to background ratio which results, increases the sensitivity of detection over that obtained with the d.c. arc alone.
Element, as Oxide
Element, as Oxide, %
A1203
85.90 8.50 3.20 2.00 0.13 0.08
Si02 CaO MgO Fez03 Ti02
1
I to2
I
-10
-06
-08
-02
-04
0
E L I 3321 c9 Lu 3312 I I
Figure 2. lium
Analytical curve for beryl-
A mixture of 1.5y0lutetium oxide in calcium carbonate was used as internal standard. Using one part of the internal standard mixture, ten parts of the beryllium standard, and twenty parts of high purity graphite powder, the detection limits and optimum excitation conditions shown in Tables I1 and 111 were determined.
A standard base mixture was prepared from spectrographically pure oxides (Johnson, Matthey & Co., Ltd.) to contain the major elements in the amount shown in Table I. Standard beryllium solutions were prepared from a stock beryllium solution of tested purity that contained 0.1 mg. of Be per milliliter. The standard range was from 0.01 to 1000 pg. of Be per milliliter. One milliliter of standard solution was pipeted onto a weighed amount of the standard base mixture (calculated to give a final weight containing the desired amount of beryllium as micrograms of beryllium per gram). The standards were mixed in agate mortars, dried a t 110" C., remixed when cool, and immediately transferred to dry glass sample vials.
Preparation of Analytical Curves. The standards employed for preparing the analytical curves were the synthetic standards used in the experimental work. The per cent transmittance of analytical lines and internal standard lines was measured with a n NSL microphotometer using a 12-micron slit. Background corrections were made on all lines and the values converted t o log relative
10
/ I
3! P
P
m Br
PROCEDURE
All of the work described in this paper was done with an assembly similar to the one used by Stallwood (18). A jet assembly is now commercially available from Spex Industries, Inc., that permits the use of larger electrodes. Sampling. At the present time sampling is done with a portable high volume Staplex air sampler (Staplex Corp., Fifth Ave., New York City). The samples are collected on What782
e
ANALYTICAL CHEMISTRY
0
~
09
I
~
l
l
1
,
'
~
l
i
1
-11
-09
-07
-05
-03
-01
0 *01
+03
B r I 234861 Lu
Figure 3.
265780
Analytical curve for beryllium
+I
5
'
l
~
Table
II.
Line Pairs and Sensitivity limits
Line Pairs ( 1 4 ) Be I 2348.61 Lu 2657.80 Be I 3321.086 Lu3312.11 Be I1 3131.072 Lu 2969.82
Sensitivity Limits, pg. Be/Gram 0.01-10.0 10.0-600 2.0-100
Table 111. Excitation Conditions and Spectrographic Equipment
,", 1
1
;
'
I
I
l
l
I
1
-180
-160
-140
-120
-80
-100
l
l
-60
,
!
-40
H I I t20I -20 0
BrI 332109 Lu 3312 I I
Figure 4.
Analytical curve for beryllium
0
A
Control standard 100%AhOs 13?&Ah03
intensity ratios on a Respectra calculating board. Log relative intensity ratios against micrograms of beryllium per gram were plotted on semilogarithmic paper for the line pairs Be - 113131.072 Be I 3321.086 and Lu 2969.82 Lu 3312.11 Be I 2348.61 Lu 2657.80 Analytical curves for Be 3131.07 and Be 3321.08 were perfectly linear over the concentration limits used (Figures 1 and 2). The Be 2348.61 curve was linear from 0.01pg. Be to 2.0 pg. Be. At concentrations greater than 2 pg. there is some self-reversal (Figure 3). Sample Treatment. Samples collected on K h a t m a n No. 41 filter paper a r e burned in platinum crucibles. T h e ash is weighed on a Sauter microbalance, mixed with internal standard a n d high purity graphite i n the ratio of 10:1:20 and arced using the experimental conditions given in Table 111. INTERFERENCE STUDIES
The effect on the beryllium intensity by a change in alumina or silica concentration was considered a possible source of error. I t was also felt that change in matrix might be serious. Synthetic standards were, therefore, prepared ranging in composition from 100 to 13%
aluminum oxide. Because i t wks not anticipated t h a t elements other than aluminum, silicon, and possibly iron would be present in the air-borne dust in excessive amounts, no attempt was made to study other compositions. Using the original base mixture as the control, a series of standards with varying alumina, silica, and iron content was prepared t h a t contained from 0.05 to 600 pg. of beryllium. These were burned as described above. Statistical evaluation of the data so obtained supports the conclusion that the effect of varying alumina or silica is not significant and should introduce an error no greater than predicted b y the standard deviation obtained with the control standards (Figure 4). ACCURACY AND PRECISION
Synthetic samples containing 2 to 50 p.p.m. of beryllium were prepared and analyzed. Beryllium was also determined in a sample of standard granite G-1 ( 5 ) . Values reported for beryllium in the standard granite G-1 range from 2 to 3.3 pg. ( I , 11). Table IV is a comparison of the results obtained by the spectrographic method described. RESULTS AND DISCUSSION
Evaluation of the data obtained in this investigation indicates t h a t the method is suitable for the rapid deter-
Excitation: Baird-Atomic Spectrosource, Model LITr-1 Source: d.c. arc Current: 11 amperes Voltage: 220 volts d.c. Analytical gap: 2 mm. Exposure time: Burned t o completion Spectral region: 2100-3500 -4.first order, 4225-7025 A. second order Dispersion: Reciprocal linear 2.72 b./mm. for 3100-A. region Type of electrodes: Sample electrode: United Carbon re formed l / 8 incg ultra purity type 5440 Counter electrode: United Carbon preformed '/a inch ultra purity Type 500 1 Spectrograph Spectrograph: Baird-Atomic 3meter grating spectrograph Model GX-1 Seven-step Sector: Stallwood jet: Carbon dioxide gas f l o ~7 liters per minute Emulsion: Eastnian Type SA kl Development: 3 minutes a t 21" C. in Eastnian Kodak D-19 Slit : 25 microns
mination of beryllium in air-borne dust even when considerable variation in sample composition is encountered. The precision that can be expected in the 2- to 50-pg. range is from k0.4 to A 4 pg. of beryllium a t the 95% confidence level. The d.c. arc in carbon dioside gas is a comparatively new method, and further experimental work may suggest modifications which will further improve its usefulness. The most obvious advantage to its use is the elimination of cyanogen interference. Others are the smoother burn obtained, the enhancement of certain elements, improved line VOt. 34, NO. 7, JUNE 1962
783
(9) Laitinen. 19) Laitinen, H. A A,. Kivalo. Kivalo, P.. P., .INAL. .IXAL.
ACKNOWLEDGMENT
Table IV. Precision Data for Beryllium Determination
(fine determinations) Standard Deviation Av. Be From Found Mean.
Be Concentration, pg. -4dded Peg. 2 (synthetic sample) 2 *0 2 f l 10 (synthetic sample) 10 f l 20 (synthetic sample) 20 f 2 50 (synthetic sample) 51 2 3 f 0 3 Standard granite G-1’ Reported values 2 to 3.3pg. Be ( 1 , 11).
\
The author thanks AC Spark Plug Division, General hIotors Corp., for permission to publish this paper. LITERATURE CITED
(1) Ahrens, L. H., “Quantitative Spectrochemical Analysis of Silicates,” Perga mon Press. London. 1954.
Ibid., p.‘970.‘ f.51 Fairbairn. H. W..Geochim. et Cosmochzm. A c t a 4, 143 (i953).
(4) \ - ,
~
(6) Hodge, W.,“Some Sotes on Safe Handling Practices for Bwvlliuni,” Defense- Metals Information Center Memorandum 2, Battelle Memorial Center (1958). ( 7 ) Joensuu, O., “The Spectrochemical Analysis of the Rare Earths, Seandium, and Thorium Using the Stallivood Arc,” Paper presented a t the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, PIIarch 2-6 (1959). (8) Joensuu, O., Suhr, K.,personal communication. ”
to background ratio, and the better control over interelement effects i t affords. The method has been extended to other elements and a fusion technique has been developed which will give quantitative data for major and minor concentrations of some 25 elements in a wide variety of materials.
,
,
-
I
CHEM.24,’ 24, 1467 (1952). (10) Landis, F. P., Coons, 311. C., A p p l . Spectroscopy 8, 7 (1954). (11) Merrill, J. R., Honda, AI., Arnold, J. R.. R., “Proc. 2nd Intern. Conference on Peaceful Uses of Atomic Energy,” Vol. 2, 251, 1958. (12) O’Xeil, R . L., Suhr, N. H., A p p l . Spectroscopy 14-2, 45 (1950). (13) Owen, L. E., Delaney, J . C., Seff, C. N.. Am. Ind. H u a . d s s o c . Quart. 12. 112 11951’1. (14) ‘Saidei, A. ‘ S., Prokofjew, W. K., Raiski, S. M.,“Spektral Tabellen,” 1st. ed., Berlin, 1961. (15) Shaw, D. M., Wickremasinghe, G., Yip, C., Spectrochim. A c t a 13, 197 (1938). (16) bill, C. W.>Willis, C. P., .&SAL. CHEM.31, 598 (1959). (17) Sill, C. W.,Willis, C. P., Flygare, J. K., Ibid., 33, 1671 (1961). . Ani. 118’1 Stallwood. B. J.. J . O D ~ SOC. ‘ 44, 171 (1954). (19) Tingle, W. H., blatocha, C. K.. h . 4 ~ CHEM. . 30,494 (1958). RECEIVED for review December 26, 1961. rlccepted April 17, 1962. Pittsburgh Conference on ilnalvtical Chemistrv and Applied Spectroscopy, Pittsburgh,” Pa., liarch 1962. l”
Concentration Method for the Spectrochemical Determination of Seventeen Minor Elements in Natural Water WILLIAM D. SILVEY and ROBERT BRENNAN Geological Survey,
U. S. Departmenf of the Interior, Sacramenfo, Calif.
b A method for the quantitative spectrochemical determination of microgram amounts of 17 minor elements in water i s given. The chelating reagents 8-quinolino1, tannic acid, and thionalide are utilized to concentrate traces ( 1 to 500 pg.) of aluminum, cobalt, chromium, copper, iron, gallium, germanium, manganese, nickel, titanium, vanadium, bismuth, lead, molybdenum, cadmium, zinc, and beryllium. Indium i s added as a buffer, and palladium is used as an internal standard. The ashed oxides of these 17 metals are subsequently subjected to direct current arcing conditions during spectrum analysis. The method can be used to analyze waters with dissolved solids ranging from less than 100 to more than 100,000 p.p.m. There i s no limiting concentration range for the determination of the heavy metals since any volume of sample can be used that will contain a heavy metal concentration within the analytical range of the method. Both the chemical and spectrographic procedures are described, and precision and accuracy data are given. 784 *
ANALYTICAL CHEMISTRY
A
which would permit the quantitative determination of a large number of elements in a microgram per liter concentration was needed for a study of the distribution and abundance of minor elements in the waters of California. -4 literature search indicated that the spectrochemical methods of Mitchell and Scott (3) and Heggan and Strock ( 2 ) would be suitable for the project. Both methods involve the concentration of the minor elements by precipitation with 8-quinolino1, tannic acid, and thionalide. This paper describes a modification of the above methods involving an increased concentration of the radiation buffer and the use of a different internal standard. The elements aluminum, beryllium, bismuth, cadmium, cobalt, chromium, copper, iron, gallium, germanium, manganese, molybdenum, nickel, lead, titanium, vanadium, and zinc can be determined in a concentration range of 1 to 500 pg. METHOD
EXPERIMENTAL
Reagents. T h e ammonium acetate
solution ( 2 N ) was prepared by mixing 1 liter of 4X ammonium hydroxide
solution n-ith 1 liter of 4 9 acetic acid solution. Reagent grade ammonium acetate n as found to contain excessive concentrations of trace elements. All other chemicals used were commercially available and of reagent grade. The indium, palladium, all chemicals used to prepare standard solutions of the trace elements, and synthetic samples were ,Johnson RIatthey and Co. specpure chemicals obtained from the Jarrell-Ash Co., S e n tonville, Mass. Apparatus. A Jarrell-A\sh 2.4meter TYadsn orth grating spectrograph equipped n i t h a 15,000 lines per inch grating ha\ ing a reciprocal lin-ar per mm. in the dispersion of 3.5 second order n a s used. X direct current arc of 240 volts a t 6 amp. \\as used for excitation, and spectral line density was measured Itith a Jarrell-Aksh projection niicrophotometer. Xational Spectrographic cupped graphite electrodes No. 3909 specially machined with a thin cup nall Jvere used. Spectra were recorded on Eastman Kodak SA-1 spectrum analysis film. Procedure. Filter t h e nxter sample through a Nillipore membrane having a pore size of 0.5 micron and select a suitable aliquot which conA\,
