As in the determination of hexafluorophosphate, fluoride ion did not interfere a t the indicated concentration levels to a significant extent. The results obtained with bot'h methods were somewhat lower than those obtained using the Nitron procedure with the empirical correction factor. When no correction factor was applied to the weight of the Nitron tetrafluoroborate precipitate, the procedures were in agreement. The precision obtained with the spectrophotometric method was rather poor, but was within the permissible precision for a spectrophotometric determination. The relative standard deviation was increased because the method involved taking a difference. Ammonium ion will interfere when
present in large quantities because of a slight absorption a t 220 nip. Using a blank as reference will remove this interference. The gravimetric method using TPAC would appear to have three advantages over the Nitron procedure. TPAC is a much more stable reagent than Nitron, the TPAB precipitate is purer than the Nitron tetrafluoroborate precipitate, and the procedure as developed can be used for smaller amounts of tetrafluoroborate. The ammonium tetrafluoroborate sample was almost certainly not stoichiometrically pure, and development of an empirical correction factor for the TPAC gravimetric method would not seem worthwhile. Also, it is felt that the analytically determined
value using the Nitron procedure is better than the empirically corrected value. LITERATURE CITED
(1) Affsprung, H. E., Archer, T7. S., A y . 4 ~ . CHEM.35, 1912 (1963). (2) Coursier, J., Hure, J., Platzer, R., Anal. ('him. Acta 13, 3T9 (1955). (3) Lange, W.: X e r . 59A, 2107 (1926). (4) Schaack, H. J., Wagner, W., Z. Anal. Chem. 146, 326 (1955). H. E. AFFSPRTTNG V. S.ARCHER' Department of Chemistry The University of Oklahoma Xorman, Okla.
' Present address, Department of Chemistry, University of Wyoming, Laramie, Wyo. WORKsupported in part by the Sational Science Foundation.
Amine Extraction-Spectrographic Determination of Tantalum, Titanium, Tungsten, and Zirconium in Plutonium Sir: Trace concentrations of tantalum in plutonium have been determined by amine extraction-spectrogra1,hic analysis ( 2 ) . This paper describes an extension of that procedure to include the determination of tantalum, titanium, tungsten, and Zirconium. EXPERIMENTAL
The apparatus, reagents, materials, and procedure used were the same as those used previously (2). The only exceptions were the use of a 20% solution of tri-n-octylamine (TnOA) in xylene instead of 50y0 and 6JI HNOs instead of 4 X . The 20y0 solution with 6M H N 0 3 gave plutonium extraction efficiencies greater than 99% in two contactings a t the 10-gram-per-liter level. RESULTS AND DISCUSSION
Plutonium is dissolved in a minimum amount of HC1 and immediately ex-
Table
I.
Effect of Fluoride on TnOA Extraction
70Recoveryo Or-
Fluoride
M
Aqueous P h E - - -
Ta
0 0 100 0.001 114 0.01 94 0.1 37 1.0 0 Obtained with amine phase.
Ti
W
Zr
ganic phase Pu
98 96 110 95 75 104 110 96 92 80 81 94 99 94 101 60 97 88 110 30 one contacting of the
tracted into 20% TnOA after adding HN03. Some HCl (no greater than 0.5M) is therefore present during the extraction; concentrations up to l M l however, still produced quantitative recoveries of tantalum, titanium, tungsten] and zirconium. The effect of fluoride on the extraction was studied. Results are shown in Table I. Tantalum extracted in the presence of fluoride, but, even with 1M fluoride] titanium, tungsten, and zirconium did not. Plutonium extraction decreased with an increase in fluoride concentration. The method is based on the assumption that plutonium can be dissolved and extracted without loss of the analytical elements whether they are dissolved or not. The validity of the method is proved if the analytical elementq in solution are shown not to extract and if insoluble forms of those elements are recovered quantitatively in the aqueous phase. The data of Table I show that the ions in solution are not extracted. To test the insoluble forms, the elements were added as insoluble oxides to the aqueous phase and analyzed gravimetrically after the extraction. Excellent recoveries were obtained. The data are shown in Table 11. In addition, spectrographic analysis of the organic phase revealed less than 1 pg. of the added elements. The organic phase was evaporated and ignited a t 650' C. in the presence of germanium dioxide which was then transferred to a crater electrode and burned to completion in a direct current arc.
Table I11 lists the wavelengths of the lines used, their excitation potentials ( I ) , and boiling points ( 3 ) . Siobium whose boiling point and excitation potential are close to those of the analytical elements was chosen as the internal standard.
Table II. Recovery of Insoluble Oxides through TnOA Extraction
Added,
Found,
mg.
mg.
5 2
5 0 12 2
Oxide TaL%
Recovery, L7
/G
96 2 12 7 98 8 TiOn 4 6 4 8 104 19 3 19 7 102 ZrOt 8 2 8 1 98 1 15 8 15 5 98 6 \VOsa 10 1 10 4 103 28 9 28 5 98 6 Ignition after the extraction was made in a muffle furnace kept below 700" C.
Table 111.
Element Ta Ti If' Zr Nb
Spectrographic Data
WaveWavelength, length, A.
3012 3361 2946 3391 3094
54 21 98 98 18
Excitapotentiori tion potential. tial, e.v. >3 7
io
F,
>5 3 10 7 >8 0
VOL. 36, NO. 13, DECEMBER 1964
Boiling Boiling mint. point, "C. . "C 5425
x- -x_n_ 5930 3580 4927
2513
Table IV. Recovery of Metals through the TnOA Extraction-Spectrographic Procedure
Recov- Rel. Added, Found,& ery, std. dev., Metal Ta Ti W
pg.
pg.
70
50
46 0 98 44
92 98 88 110
7%
f8.4 1 f4.9 iz5.7 50 Zr 1 1.1 iz9.0 Av. f 7 . 0 Average of 6 determinations.
The method was tested by spiking plutonium solutions with the metals of interest and measuring their recoveries throygh the TnOA extraction-spectrographic procedure. The data are shown in Table 1V. Eighty-eight to 100% spike recoveries were obtained. On 24 such measurements, a relative standard deviation of +7% was estimated. Fifty to 2000 p.p.m. of tantalum and tungsten and 5 to 200 p.p.m. of titanium and zirconium in 100 mg. of plutonium are conveniently determined.
LITERATURE CITED
(1) Harrison,
G. R., "Wavelength Tables," pp. XTIII-XX, The Technology Press, Wiley, New York, 1939. ( 2 ) K O , R., ANAL.CHE'vf. 36, 1290 (1964). (3) "Metals Handbook," 8th ed., ToI. 1, pp. 46-7, American Society for Metals, Cleveland, Ohio, 1961. ROYKO Hanford Laboratories General Electric Co. Richland, Wash.
Use of Porous Glass for Gas Chromatographic Separation SIR: Porous glass has recently been used as a gas-chromatographic separation medium (1, 2 ) . An attempt was made in this laboratory to extend this technique to the separation of highboiling materials. X temperature programmed Aerograph Hy-Fi 600-C, with the flame ionization detection system, was used in this study. The gas chromatograph was equipped with an Aerograph hydrogen generator. stainless steel column, 6 feet long, '/,-inch 0.d. was packed with untreated porous glass (Corning Glass Co. Code 7930), 50- to 80-mesh size. Surface characteristics of porous glass were determined using the Isorpa made by Engelhard Industries and found to be: surface area, 173.2 sq. meter per gram; pore volume, 0.109 ml. per gram; average pore size, 25.2 A. In the initial experiment, separation of lower saturated and unsaturated (C,-C,) hydrocarbons was attempted. Methane, ethane, propane, isobutane, n-butane, and unsaturated Cd hydrocarbons were separated. X mixture of normal pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, and hexadecane was then prepared and separation attempted under temperature programmed conditions. h perfect resolution of all hydrocarbons was obtained as shown in Figure 1. No tailing of peaks was observed. The highest boiling comppund of the series, hexadecane (b.p. 287.5"C.), was eluted a t a temperature of approximately 250" C. in 30 minutes. To establish an upper temperature limit for the use of this adsorbant, the following experiment was conducted. A gas chromatographic column used for the separation of hydrocarbons was placed into a muffle oven a t 850" C. for 2 hours. ;\fterwards this column was used for the separation of the same hydrocarbon mixture. Identical results were obtained in terms of retention time and peak symmetry. The experiment indicated that temperatures as A \
251 4
ANALYTICAL CHEMISTRY
high as 850" C. do not affect adsorbant characteristics of porous glass and that the column can be operated up to temperatures a t which pyrolytic decomposition of specific analyzed materials begins. An attempt to use this column for the separation of polar materials was unsuccessful because of an extremely high degree of affinity between the polar material and porous glass. Partial success has been obtained with a modified porous glass. Modification was accomplished by coating porous glass grains with 0.6 and 3.0y0 phenolformaldehyde resin. A sample of methanol which was almost completely retained on an untreated porous glass
Figure 1 .
Separation of
produced a definite peak on the polymer treated porous glass. LITERATURE CITED
(1) hlacDonel1, H. L., Soonan, J. AI., Williams, J. P., ASAL. CHmf. 35, 1253 (1963). ( 2 ) Zhdanoff, S. P., et al., Seftokhimza 3 , 418 (1963). IHOR LYSYJ P. R. XEWTOX Research Department Rocketdpne Division of Xorth American Aviation, Inc. Canoga Park, Calif. WORKsupported by the U. S. Department of Interior, Office of Saline FTater, Contract N o . 1401-0001-332.
Cg to CX saturated
hydrocarbons
Instrumenk Aeragraph HY-Fi, M a d e l 6 0 0 - C Detector: Flame ionization; H2 flow, 20 cc. p e r minute; oir flow, 2 5 0 cc. p e r minute Column: 6 feet long b y '1s-inch diameter packed with Corning porous glass No. 7930, 50- to 80-mesh size Sample: Mixture o f Cg to Cla saturated hydrocarbons; sample size, 0.5 pi. Carrier gas: Nitrogen; Inlet pressure, 35 p.r.i.g. Temperature: Programmed from 75' to 250' C. Sensitivity: 100 X 16 Recorder: Varian, 9-mv. full scale response; speed, 2.5 inches p e r minute Peaks in order of elution: n-propane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-unidecane, n-dodecane, n-tridecane, n-tetradecane, n-hexadecane
