and 2,3,@trimethylnaphthalene by Carruthers and Douglas (S), 1,3,6-, 1,2,6and 1,2,and 1,3,8-trimethylnaphthalene 6,8-tetramethylnaphthalene by Soko1’nikova and Simkheave ( 1 5 ) ,and 2,3,6,7tetramethylnaphthalene by Mair and Martin&-Pic6 (la). As already noted, 1,2,7-trimethylnaphthalenewas not detected in the present investigation though it may be present in small amount. The reported finding of 1,3,8trimethylnaphthalene and 1,2,6,8-tetramethylnaphthalene needs verification. Four dimethylbiphenyls without ortho-substituents out of five possible isomers were found. Alkylbiphenyls with more than 16 carbon atoms are present in a relatively small amount; they are expected to have a t least one ortho-substituent. The alkylbiphenyls found in this investigation have not previously been reported as constituents of petroleum. Acenaphthenes, which belong to the same mass series, CnH2,,--14, as the biphenyls were not found in this fraction of petroleum. Recently, dibenzofurans have been detected in the trinuclear aromatic portion of a high sulfur and nitrogen crude oil by Lumpkin (7) using high resolution mass spectrometry, and by
Hartung and Jewell from ultraviolet absorption spectra ( 5 ) . An examination of the ultraviolet spectra of fractions obtained from the trinuclear aromatic portion (305’ to 405’ C.) by Mair and MartinBz-Pic6 ( l a ) has shown that they also contain dibenzofurans (9). ACKNOWLEDGMENT
Grateful acknowledgment is made to R. W. Vander Haar, American Oil Co., and to Gilbert J. Mains, Carnegie Institute of Technology, for the mass spectral data; to Gerald L. Carlson, Mellon Institute, and Robert J. Kurland, Carnegie Institute of Technology, for the NMR data; to William E. Mott, Gulf Research and Development Co., for the oxygen analyses; and to Ned C. Krouskop for supervising the distillation operations. LITERATURE CITED
( 1 ) American Petroleum Institute Research Project 44, Infrared Spectral
Data.
(2) Beaven, G. H., Johnson, E. A., Spectrochim. Acta 14, 67 (1959). (3) Carruthers, W., Douglas, A. G., J . Chem. SOC.1955, 1847. (4) Gavat, I., Irimescu, I., Ber. 75, 820 (1942).
(5) Hartung, G. K., Jewell, D. M., Anal. Chim. Acta. 26, 514 (1962). (6) High Resolution NMR Spectra Cat-
alog. Varian Associates, Palo Alto, Calif. (7) Lumpkin, H. E., ANAL. CHEM.36, 2399 (1964).
(8) MacLean, C., Mackor, E. L., Mol. PhzJs. 3, 223 (1960). (9) Mair, B. J., unpublished data. (10) Mair, B. J., Barnewall, J. M., J . Chem. Eng. Data 9, 982 (1964). (11) Mair, B. J., Mayer, T. J., ANAL. CHEM.36. 351 (1964). (12) Mair, ’B.-J.] Martin&-Pic6, J. L., Proc. Am. Pet. Znst. 42 [III], 173 (1962). (13) Paserini, R., Righi, G., Bull. Sci. Fac. Chim. Znd. Boloqna 10, 166 (1952). (14) Pople, J. A., Schneider, W. G., Bernstein, H. J., Can. J . Chem. 35, 1060 (1957). (15) Sokol’nikova,
M. D., Simkheave, N. G., Issled. hlineral’n i Rast. S’yrya Uzbedistana. Akad. Nauk. Uz. SSR, Znst. Kchim, 1962, 116. (16) Yew, F. F., Kurland, R. J., Mair, B. J., ANAL.CHEM.36, 843 (1964). RECEIVED for review March 5, 1965. Accepted December 12, 1965. Division of Petroleum Chemistry, 150th Meeting, ACS, Atlantic City, N. J., September 1965. Work supported by the American Chemical Society Petroleum Research Fund and the American Petroleum Institute. Taken from a thesis submitted by Foch Fu-Hsie Yew in partial fulfillment of the requirements for the Ph.D. Degree at the Carnegie Institute of Technology.
Gas Chromatographic Analysis of Solvent Used in Reactor Fuel Reprocessing and Fission Product Recovery MILTON H. CAMPBELL’ General Electric Co., Richland, Wash.
b Gas chromatography is a valuable technique for measuring the solvent quality of organic extractants used in reactor fuel reprocessing. Retention data and column characteristics are presented for tributyl phosphate, dibutyl butyl phosphonate, di(2-ethyl hexyl) phosphate, trioctyl phosphine oxide, tertiary amines from Ca to C~Z, and straight chain hydrocarbons from Cs to Clz. Quantitative calibrations for each of the extractants in hydrocarbon or carbon tetrachloride diluents are discussed. Standard deviations for the calibrations are h 0 . 2 to k0.3 volume per cent of the extractant. Detection levels of one extractant as a contaminant in another are determined.
S
extraction has been widely applied to reprocessing spent fuel elements and resultant waste solutions Present address, Isochem Inc., Richland, Wash. OLVENT
using such processes as the Purex process (6) and the strontium-90 recovery program (13). Up to the present, many of the problems concerning the solvent preparation and analysis have been treated very generally. On the other hand, engineering technology has progressed rapidly over the past five years, with use of different extracting systems for product recovery, waste treatment, and fission product recovery. Much concern has been evidenced over the possibility of mixing two extractants inadvertently with unforeseen results in the plant processes. Standard solvent measuring techniques include oscillometry ( l l ) ,nitric acid distribution ratio (16), liquidsolid chromatographic separation on activated alumina with a phosphate determination (IC),and infrared absorption spectrometry (16), all for tri-nbutyl phosphate (TBP), and nonaqueous acid titration for di(2-ethyl hexyl) phosphoric acid. Of these methods,
only the chromatographic separation and infrared analysis are in any measure specific. The first is very timeconsuming. While the second has proven to be a useful tool, the solvent spectrums are quite complex and the technique suffers from fairly high detection level requirements, especially in the case of cross contamination with other extractants. Gas chromatography seemed to offer a solution to the problems of solvent analysis in the form of a versatile instrumental technique that would provide timely and specific analysis. This same technique should be adaptable enough to keep abreast of future process changes. Prior work on gas chromatographic separation and identification of organophosphate compounds centers chiefly around pesticides. The stability of these compounds in contact with metal a t elevated temperatures is very poor; consequently, pyrolysis with subsequent VOL. 38, NO. 2, FEBRUARY 1966
237
measurement of released olefins was used by Legate and Burnham (8) to overcome this problem. Higgins and Baldwin (5) used a pyrolytic technique to measure the rate of degradation of TBP, identifying and measuring degradation products with gas chromatography. Hardy(4) used gas chromatography to measure the methyl esters of di-butyl phosphate and monobutyl phosphate that were formed with diazomethane. A phosphate specific flame ionization detector was described by Karmen (7) with mention of application to TBP. A similar detector was described by Giuffrida (3) for use with pesticides. Cook, Stanley, and Barney (1) investigated the detection of phosphate pesticides with electron affinity detectors. Trilauryl amine and several other liquid anion exchangers are used in reclaiming actinides from waste solutions (12). Gas-liquid chromatography of fatty acid amines was discussed by Link, Morrissette, Cooper, and Smullin (9). They recommended the use of nonpolar liquid substrates, such as Apiezon L or Dow Corning high vacuum grease on Chromosorb W, previously treated to reduce adsorptivity. Later,
Table 1.
Compound Tri-n-butyl phosphate Dibutyl butyl phosphonate Dibutyl methyl phosphonate Di( 2-ethyl hexyl) phosphoric acid
Tridecyl amine Didodecyl amine Tridodecyl amine Is0
octane
Decane Dodecane Tetradecane a
Link (10) recommended the use of Apiezon N for amines containing more than 36 carbon atoms. The purpose of this investigation was to find the extent that gas chromatography could be applied to the measurement of specific organic components in process solvents. Of specific interest mere tri-n-butyl phosphate (TBP), di(2-ethyl hexyl) phosphoric acid (D2EHP), dibutyl butyl phosphonate (DBBP), trilauryl amine (TLA), and trioctyl phosphine oxide (TOPO). The ability to detect cross contamination of extractants was also of interest, EXPERIMENTAL
Apparatus. A Barber - Colman Series 5000 gas chromatograph equipped with a hydrogen flame detector was used. The chromatograms were recorded on a 0- t o 5-mv. BarberColman strip chart recorder equipped with a Disc integrator. A &foot, 1/4-inch o.d., stainless-steel column containing 20% Apiezon K on Chromosorb W, 60/80 mesh, was used throughout this investigation. Helium was used as the carrier gas at the indicated flow rates. Columns were operated, isothermally, a t temperatures ranging from 150' C. to 325' C. The
Retention Data and Column Characteristics" for Organic Extractants and Diluents
Carrier Temp., flow Rel. ' C. (cc./minute)* retentionc 150 175 200 300 325 150 175 200 150 175 200 150 175 200 300 325 300 325 300 325 300 325 300 325 150 175 150 175 150 175 150 175
182 61 54 93 80 182 61 54 182 61 54 182 61 54 93 80 93 80 93 80 93 80 93 80 182 61 182 61 182 61 182 61
10.0 10.0 10.0 10.0 10.0 9.3 8.8 9.5 2.9 3.4 3.9 0.6 0.9 1.4 208 153 53 46 226 165 189 85 1111 622 0.2 0.4 0.5 0.8 1.5 2.0 4.4 5.0
nd
R"
919 1230 1125
...
...
...
... I
.
.
... ...
956 1133 1024 652 659 822 455 380 225 895 468 737 84 841 484 38 292
0.55 1 .o 0.40 8.0 8.0 7.3 13.3 10.7 11.8 10.2 6.9 4.3 2.7 11.8 7.2 2.7 6.4
890 144 207 225 642 604 69 1 1024 1419
12.7 14.1 15.4 13.3 14.4 10.9 11.0 5.9 6.1
...
...
Conditions: see text.
* Measured carrier flow rate at the indicated temperature.
Relative to TBP = 10. n = 16 (t~/Wt,)= number of theoretical plates; tal retention time from injection point to peak maximum; Wb, base line intercept cut by tangents to peak inflections. All e R = ~t divided by (Wbl + W&)/2; At, retention time between peak maxima. resolutions are in reference to TBP. c
d
238
ANALYTICAL CHEMISTRY
injection block temperature was maintained 50" C. higher than the column temperature. A hydrogen flow rate of 38 cc./minute was used for the detector. The detector was operated at a n amperage of 3 X 10-9 at full chart scale, a t an output sensitivity of 1OX and attenuated between 1x and 128X. The sample in liquid form was injected with a 10-b1. syringe (Hamilton #701). Reagents. Tributyl phosphate, di(2-ethyl hexyl) phosphoric acid, and dibutyl butyl phosphonate were purified by vacuum distillation of the commercial material. Trioctyl amine, tridecyl amine, di-n-dodecyl amine, iso-octane, decane, dodecane, and tetradecane were obtained in the practical form from Distillation Products Industries (DPI), and used with no further purification. Trioctyl phosphine oxide and tridodecyl amine were purchased in the reagent grade from DPI. Trilauryl amine, Soltrol, and Normal Paraffin Hydrocarbons (NPH) were procured as trade name items, and used with no further purification. Mixtures of the above chemicals were prepared on a volume basis. Procedure. TBP, DBBP, D2EHP. The column temperature was set at 175' C., and the injector temperature a t 225' C. The helium pressure was adjusted to 10 p s i . (61 cc. per minute at 175' C.), A 4-pl. sample was injected which consisted of a mixture of any of the above chemicals and a hydrocarbon diluent. To test a single chemical for impurities, the column was set a t a temperature of 200" C., and a carrier gas flow was set a t 10 p.s.i. (54 cc. per minute). This provided a faster analysis that was satisfactory as long as no hydrocarbon diluents were present. TOPO AKD TERTIARY AMINES. The column temperature was set a t 325' C. and the injector temperature was set a t 375' C. The helium pressure was adjusted to 20 p.s.i. (80 cc. per minute at 325' (2.). A 4-pl. sample was injected which consisted of any of the above chemicals and a hydrocarbon diluent . When mixtures of the amines and lower boiling organophosphates are suspected, two samples should be injected, one a t each temperature and carrier flow-rate setting. For routine analysis of such a mixture, the higher temperature setting with a change in flow rates (after the organophosphate is eluted) could also be used for T B P and DBBP. RESULTS AND DISCUSSION
-in ionization detector specific for phosphates was initially considered for this investigation. However, tests with a flame ionization detector showed an adequate sensitivity and a quantitative recovery for the organophosphate compounds of interest. Since the latter detector was more generally applicable in the laboratory, a phosphate specific detector was not used.
tertiary amines, temperatures in excess of 325" C. caused a high bleed rate of the liquid phase (Apiezon N). I n addition to the extractants, data are presented for straight chain hydrocarbons between Cs to CL4. A multitude of trade name diluents are used in industry, and there is a trend toward diluents with higher purity in specific hydrocarbons. While many of these diluents were not readily available, all probably contained a t least one of the referenced hydrocarbons as a principal component. Quantitative Analyses. A typical chromatogram for the 30 volume per cent T B P in N P H diluent (30 vol. TBP-NPH) system is shown in Figure l(a). The calibration of T B P in this system had a standard deviation of =t0.3 vol. % for solvents containing 1 to 100 vol. % TBP. Figure l ( b ) shows a chromatogram of commercial grade TBP. The low boiling components were butanol and dibutyl phosphate (DBP) in that order. The DBP, present as a hydrolysis product of TBP, underwent pyrolysis on injection and had no discrete peak. These decomposition products eluted from the column in the first 5 minutes. DBP concentrations as high as 1 vol. % in 30 vol. yoT B P were injected, and no interference was found with the quantitative measure of TBP. Both butanol and DBP were removed from commercial grade T B P by vacuum distillation. Dibutyl butyl phosphonate is used to remove plutonium values from waste solutions ( 2 ) . Figure 2(a) shows a chromatogram of commercial grade DBBP. The first peak on the chromatogram is dibutyl methyl phosphonate (DBMP) which occurred in concentrations of 10 to 15 vol. % in all the commercial batches tested. The process solvent used carbon tetrachloride as a diluent, so there was no problem encountered in resolving the extractant from the diluent. The calibration for
(a1 u)% TBPlNPH (b) Commercial TBP
Attenuation
L r
4
0
16 20 24 28 Retention Time(minutes)
12
8
Figure 1 .
0
4
8
12
Chromatograms of tributyl phosphate
(a) He carrier: 61 cc./minute; column: 1 7 5 ' C.; 1: Decane; 2: Undecane; 3: Dodecane; 4: Tridecane; 5: TBP ( b ) He carrier: 54 cc./minute; column: 200' C.; 1: Butanol; 2: DBP; 3: TBP
Gas Chromatographic Characteristics. Retention data and column conditions for the organic compounds of interest are presented in Table I. I n addition t o the recommended column operating conditions, data were collected for temperatures over t h e 150" t o 325" C. range to provide information for analysis of new process solvents. Tributyl phosphate was used as the reference compound since this is the most common extractant used in reactor fuel reprocessing. A relative retention period of 10 was assigned T B P a t each temperature and flow rate, because its elution period was generally greater than the other components of the extraction systems. The theoretical plates, n, and peak resolutions, R, indicated good separation potentials for most organic extractant systems. T B P could be separated from
6t-
all listed compounds with the exception of DBBP. The usual hydrocarbon diluents did not interfere with T B P measurement a t any temperature below 200" C. D2EHP appeared to decompose on injection with release of more volatile products; thus, a good separation was made from TBP. There was a possibility of interference from diluents containing decane when evaluating D2EHP concentrations, however. From Table I it is apparent the tertiary amines require a temperature of a t least 300" C., substantiating the work of Link, Morrissette, Cooper, and Smullin (9). The position of the T B P peak in relation to these amines indicated the tertiary amines could be readily detected in T B P extractants. While a higher column temperature should improve peak resolution of the
(a) Commercial DBBP 2
I
5n al
a
1
;
0
4
12
8
(b) 4.5% D B L - 6.8% TBP
I
n
Attenuation - 16X
I\ 16
- CCI4
20
24
i-
28
32
c:6 6 al
-
Attenuation 2X
2
3
4
A
2
\
n 0
4
8.
12
16
20
24
28
32
Retention T i m e (minutes)
Figure 2. phonate
Chromatograms of
0
dibutylbutyl phos-
Column conditions see text; H e carrier: 61 cc./minute; 175OC. (a) 1: DBMP; 2: DBBP ( b ) 1: CC14; 2: DBMP; 3: DBBP; 4: TBP
4
0
Figure 3. column
12
16
M
24
20
32
Retention T i m e (minutes)
10% D2EHP-6% TBP-NPH
Coiumn conditions: see text; He carrier: 61 cc./minute; column 175'C. 1: D2EHP 4- decane; 2: undecane; 3: dodecane; 4: tridecane; 5: TBP
VOL. 38, NO. 2, FEBRUARY 1 9 6 6
239
(a) Tertiary Amines: Cg. Cl0, C12
Table II. Detection of Extractant Contamination in Common Plant Solvents
VOl. contaminant detectable,
Contaminant Solvent % DBBP 20y0 TBP in CCla 0. l b D2EHP 3oy0 TBP in Soltrol 0. l b TLA 30% TBP in Soltrol 0.005" TBP D2EHP in NPH 0.01b TBP 30% DBBP in CCL 0.5b TBP 10% TLA in Soltroi 0.01b Conditions: see text. Column temperature, 325" C.; He carrier gas flow rate, 80 cc./minute. b Column temperature, 175' C.; He carrier gas flow rate, 61 cc./minute.
4t-
-
I
Attenuation
128X
512X
-
(1
2LA
0
DBBP had a standard deviation of 1 0 . 3 vol. % over the 0.9-100 vol. % concentration range. Vacuum distillation provided a pure DBBP fraction for calibrations. A D2EHP-TBP-NPH solvent system is used in fission product recovery (IS) (Sr-%, Ce-lr4, Pm-147). While the D2EHP can be measured by caustic titration in a nonaqueous media, no reliable procedure has been reported for TBP. Figure 3 shows a chromatogram of this solvent system. The D2EHP peak was probably that of a degradation product, since the boiling point, found by differential thermal analysis, was 252' C. a t about 1 atmosphere of pressure. Calibrating on this peak, D2EHP was determined with a standard deviation of 1 0 . 2 vol. % between 6 and 20 vol. % concentration (0.17 to 0.56M). Tributyl phosphate was readily separated and measured with a standard deviation of ~ k 0 . 3 vol. % in the concentration range 1 to 10 vol. % (0.04 to 0.36M). Process samples which had been exposed to gross beta and gamma radiation did not vary from this chromatogram. Since TLA is a proprietary compound available from several vendors, the preparation of a calibration would depend on the chromatogram of the extractant. Probably one of the tertiary amines shown in Figure 4(a) would represent the principal component. Figure 4 ( b ) was a chromatogram of one vendor's product that was primarily tridodecylamine. A calibration of this product was made with a standard deviation of b 0 . 5 vol. '% in the range of l to 20 vol. % Extractant Contamination. The potential of accidentally mixing extractants presents a serious problem. Gas chromatography can be used for a
240
ANALYTICAL CHEMISTRY
0
4
. .
8
1
2
3
0
3
3
8
4
2
Resolution Time (minutes)
Figure 4.
Tertiary amines and trilauryl amine
Column conditions: see text; He carrier: 80 cc./minute; column: 375O c. (a) 1: trioctyl amine; 2: tridecyl amine; 3: tridodecyl amine ( b ) 1: tridodecyl amine
quantitative measure of such contamination. Column operating temperature alone could be used to determine tertiary amine contamination in TBP, or vice versa. DBEHPA-TBP contamination could also be readily checked due to the large difference in resolution. As indicated earlier, resolution between T B P and DBBP was very poor; however, the resolution between T B P and D B M P was good (8.0). Knowing the ratio of D B M P to DBBP in the initial solvent make-up, the TBP concentration was calculated by correcting the composite DBBP-TBP peak with this ratio and the D B M P peak area. Figure 2(b) shows such a mixture. T B P concentrations as low as 0.5 v./o. were detected in 20 v./o. DBBP. Table I1 indicates the levels of contamination that are detectable in several plant extractants. ACKNOWLEDGMENT
The author thanks C. A. Radasch for his technical assistance and C. W. Pollock for vacuum distillation of T B P and DBBP. LITERATURE CITED
(1) Cook, C. E., Stanley, C. W., Barney, J . E. 111. ANAL.CHEM.36.2359 (1964). ( 2 ) Creighton, D. M., U. ,$-At. Energy Comm. Rept. HW-81710 (1964).
(3) Giuffrida, Laura, J. Assoc. Ojic. Agri. Chemists 47, (1964). ( 4 ) Hardy, C. J., J . Chromatog. 13, 372 (1964). ( 5 ) Higgins, C. E., Baldwin, W. H., J. Org. Chem. 26, 846 (1961). (6) Irish, E. R., Reas, W. H., U.8. At. Energy Comm. Rept. HW-49483AI flR.57). I - - -
I
( 7 ) Karmen, A., ANAL.CHEM.36, 1416 (1964). (8) Legate, C. E., Burnham, H. D., Ibid., 32, 1043 (1960). (9) Link, W. E., RIorrissette, R. .4., Cooper, A. D., Smullin, C. F., J. Am. Oil Chemists' SOC.37, 364 (1960). (10) Link, W. E., Archer Daniels Mid-
land Co., Minneapolis, Minn., private communication, 1963. (11) Loveland, J. W. in "Treatise on Analytical Chemistry," 1st ed. Part 1, Vol. 4. D. 2625. I. M. Kolthoff. P. J.
(14) Wade, M. A., Yamamura, S. S., Ibid., TID-7655,p. 181 (1962). (15) U. K. At. Energy Authority, Prod. Group, PG Rept. 344 (1962). (16) U. K. At. Energy Authority, Prod. Group, PG Rept. 569 (1964).
RECEIVEDfor review August 5, 1965. Accepted November 22, 1965. Division of Nuclear Chemistry and Technology, 150th Meeting, ACS, Atlantic City, N. J., Sept. 1965. Work performed under Contract AT(45-1)-1350 between the Atomic Energy Commission and the General Electric Co.
