three flame< were situated centrally between the mirror-lens assemblies. Continuous radiation from the off-axis xenon arc nas focubed on the central flame by the source lens. The light traversed all three flames a t a distance of 25 mm. above the burner tip. The transmitted radiation was then reflected by mirror .-I t o mirror B. After reflection a t mirror B, the light again passed through all three flames 25 mm. above the burner tip; the transmitted light \\-as then reflected by mirror C to mirror D. The latter formed a n image of the source on the central flame 25 mm. above the burner tip. A conventionai crossed cylindrical lens sl-stem was employed to form a n image of the xenon Source on the collimating mirror of the spectrograph
(4).
The experimental conditions for the photographic recording of the spectra are summarized in Tsble I. Solutions. T h e solutions were prepared in accordance with t h e procerlurrs de-c ribed previously ( 5 , 6)
RESULTS
The wavelengths of the strongest absorption lines of these elements and their sensitivities of detection are summarized in Table 11. The latter are expressed as the concentrations required to produce a visually detected absorption line. It is evident that these lines exhibit adequate sensitivity to satisfy many analytical requirements. ACKNOWLEDGMENT
The authors are grateful to D. W.Golightly for his experimental assistance and to Richard B. Kniseley and Robert B. Myers for helpful discussions during the course of this investigation. LITERATURE CITED
(1) Allan, J. E., Analyst 83, 466 (1958). (2) Allan, J. E., Spectrochim. Acta 18,
259 (1962). (3) David, D. J., A\'uture 187,1109 (1960). (4) Feldman, C., Ellenburg, J. Y., Spectrochznz. dcta 7, 349 (1956).
( 5 ) Fassel, V. A., Curry, R . H., Kniseley, R. K.,Ihid., 18, 1127 (1962).
(6) Fassel, V. 4.,Myers, R. B., Kniseley, R. S . ,Ibid., in press. ( 7 ) Gatehouse. B. M.. Willis. J. B.. Ibid.. 17, 710 (1961). (8) Jarrell, R. F., J. Opt. Soc. Am. 45, 259 (1955). (9) Slavin, W., Atomic Absorption Newsletter, Perkin-Elmer Corp., October 1962. (10) Slavin, W., Manning, D. C., ANAL CHEV. 35, 253 (1963). VELVERA. FASSEL VICTORG. Mossom Institute for Atomic Research and Department of Chemistry Iowa State University Ames, Ion-a RECEIVED for review December 3, 1962. Accepted December 19, 1962. Contribution No. 1258. Work was performed in the h i e s Laboratory of the U. S. Atomic Energy Commission. Presented in part at the Xth Colloquium Spectroscopicum International, College Park, Md., June 21, 1962, and at the International Symposium on Molecular Structure and Spectroscopy, Tokyo, September 12, 1962.
Atomic Absorption Spectrophotometry in Strongly Reducing Oxyacetylene Flames SiR. In the pre.jent state of development of atomic absorption spectrophotometry, about 35 metals can be determined in solution a t concentrations of parts per million or less. An equally large grouli of metals resist analysis becauce, n hen their compounds dissociate in the flames that are conventionally used, oxides or hydroxides are immediately formrd, binding the metal in a refrartory compound that will not dissociate at the temperatures available. It n-ill be shown in this comniunication that, \\hen the flame conditions are properly chosen. the forniation of the oxide or hydroxide can be significantly inhibited. and an atomic vapor will be produced IT hich will absorb energy a t the reconance n avelengths. I n thic way, inany more metals can be determined d o n n to the parts per million le^ el in a +elution. This observation has heen rcy~oitcdby FasTel (6, 6). Much of the published literature on atomic ah-orption spectrophotometry describe; the use of a solution atomizer of thr p r c n i i ~type ( 3 ) . When an airncetdene flame is used in this burner and the acetylene flow is increased to the point where the flame is brightlv incandevrnt. it is 1)ossible to determine some metalc-e g., NO,Be, Ru, Cr, Snn hich absorb only slightly in a stoichiometric fuel mixture. We and others ( 2 , 8 ) have attempted to observe the atomic absorption of aluminum, vana-
dium, boron, and other metals in such a flame, but without success. Robinson (11), using a n oxycyanogen flame, detected weak absorption due to vanadium, but none a t all from the other metals mentioned. However, Dean ( 4 ) ) Fassel ( 7 ) , Gilbert (9),and others have observed emission a t the resonance lines from many of these metals in conventional total consumption burners utilizing very rich oxyacetylene flames. It seemed clear that if an atomic vapor is present that can emit radiation, it must d s o be available to absorb radiation. K e therefore modified a Perkin-Elmer Model 214 atomic absorption yiectro-
photometer (IO) to use a Zeiss total consumption burner-atomizer. Using a very rich oxyacetylene flame, we observed strong absorption from aluminum, vanadium, titanium, and beryllium solutions. (Hollow cathode lamps were used for all the analyses reported here.) Typical curves of concentration 1's. absorbance for these elements are shown in Figure 1. To observe the sensitivity indicated in the figure, use a salt of the metal which ill readily dissociate a t the temperature of the acetylene flame. For example, aluminum was present in our experiment as
"1 0.8
0 IO0 CONCENTRATION ( P P Y I
io0
Figure 1. Working curves for various metals determined in very reducing oxyacetylene flames VOL. 35, NO. 2, FEBRUARY 1963
253
Table 1.
Metal A1 Be
v Ti
Ba
Analytical Data
Wavelength, A.
Sensitivity (p.p.m./l%)
3962 2349 3184 4379 3653 3643 3999 3635 3342 3371
6.0 0.2 7.0 100.0 12.0
Salt used Chloride Chloride
12.0 16.0 16.0 20.0 53.0 3.5
5535
greatly expanded list of elements susceptible t o analysis by atomic absorption spectrophotometry.
a chloride. All of our experiments were performed with solutions containing an organic solvent. This increased the sensitivity, as has been reported by others ( 1 ) . Using a different experimental arrangement, Fassel and his co-workers (5, 6) have observed the absorption of some of these metals as well as a number of the rare earths. While this report must be considered preliminary, the analytical data in
...
Organic used Ethanol Ethanol Ethanol
Chloride Chloride Chloride Chloride Chloride Chloride Acetate
Isopropanol Isopropanol Isopropanol Isopropanol Isopropanol Isopropanol Isopropanol
EXPERIMENTAL
Reagents. Tri-n-butylphosphine was prepared b y reaction of phosphorus trichloride with a n excess of n-butyl magnesium chloride in ether under nitrogen (2, 4). The ethereal solution of tri-n-butylphosphine was treated with aqueous ammonium chloride to hydrolyze the excess Grignard reagent, then the organic layer was separated and distilled. The portion boiling a t 149 =t= 1' C. and 50 mm. Hg was taken as the butvlwhosDhine and " _ redistilled (6). Tri-n-butylphosphine sulfide was prepared by direct addition of sulfur t o the butylphosphine under a nitrogen I
254
ANALYTICAL CHEMISTRY
(1) Allan, J. E., Spectrochini. A c t a 17, 467 (1961). (2) illlan, J. E., Zbid., 18, 259 (1962). (3) Box, G. F., Walsh, -I., Ibid., 16, 2a.3 (1960). (4) Dean, J: d.,A n a l y s t 85, 621 (1960). (5) Fassel, V. A,, Proceedings of the
International Symposium on Molecular Structure and Spectroscopy, Tokyo, September 1962. (6) Fassel, V. h.,Curry, R . H., Myers, R. B., Kniseley, R . S . ,Xth Colloquium, College Park, Md., June 1962. (7) Fassel, V. A,, Myers, 11. B., Kniseley, R. S . ,Spectyochitn .-lcta, in press. (8) Gatehouse, B. AI., Willis, J. B., Spectrochiiri. A c t a 17, 710 ( 1961). (9) Gilbert, P. T., 12th .innual Symposium on Spectroscopy, May 1961. (10) Leen, M . W., .itwood, J. G., Pittsburgh Conference, March 1961. (11) Robinson, J. m., ASAL. CHEar. 33,
Table I may help guide others. The sensitivity reported represents the concentration of the metal in parts per million that will produce 1% absorption. We are continuing this work to determine the sensitivities that may be obtained with other metals previously unavailable by atomic absorption spectrophotometry. Because emission spectra have been observed from all but a few of the metallic and semimetallic elements in flames, we may expect a
Tri-n-butyl phosphine Sulfide SIR: This paper deals with a brief investigation into the behavior of trin-butylphosphine sulfide as an extractant for metal ions. This class of organic extractant, not previously investigated, provides the sulfur analog to the trialkylphosphine oxides (which includes well known TOPO). A trialkylphosphine sulfide seemed preferable to an aryl derivative because it was expected that the former compound would be prepared more easily and, furthermore, the corresponding trialkylphosphine oxides have received more study than the triarylphosphine oxides.
LITERATURE CITED
Table
I.
1067 (1961).
WALTERSLAVIX D. C. MAS~SIXG
The Perkin-Elmer Corp. Norwalk, Conn. R E C X I ~ Zfor D review Xovember 8, 1962. accepted December 19, 1962. Presented in part at the Xinth Ottawa Symposium Ottawa, Canada, September 1962.
as an Organic Extractant
Survey of Extraction of the Elements by Tri-n-Butylphosphine Sulfide)
Degree of extractiono Element
5111 HCl
Aluminum* Antimony( 111) Bismuth Boronbpc Cadmium Cerium( 111) Chromium(111) Cobalt Copper(11) Iridium Iron( 111) Lead( 11) Manganese( 11) Mercury( 11) Ruthenium Selenium(IV) Silver Strontium Thallium( 111) Thorium Tin(I1) Vanadium(V)b Zinc Zirconium-niobium
N
a
C
0.1M HCl
Water
Aqueous 3"
N
N N
iv N
-2' P
N N N
av 1V
N
N
N
P
S-P
N = no extraction (99% extraction). Extraction followed by flame spectrometric methods. Reagent concentration was 0.05M.
= b
N
1111HCl
