Anal. Chem. 1983, 55, 1107-1111
yields useful information from the analysis of multicomponent systems. A copy of the computer program used for data analysis is available upon request.
LITIERATURE CITED (1) Mark, H. B., Jr.; Rechnitz, G. A. "Kinetics in Analytlcal Chemlstry"; Intersclence: New York, 1968; Chapter 7 (2) Mottola, H. A. CRC Crit. Rev. Anal. Chem. 1974, 4 , 229-280. (3) Shuman, M. S.;Mlchael, L. C. I n "International Conference on Heavy Metals In the Envlronment: Symposium Proceedings"; Hutchinson, T. C., Ed.; Toronto, Canada, 1975; Vol. I , pp 227-248. (4) Shuman, M. S.;Michael, L. C. fnviron. Sci. Techno/. 1978, 72, 1069- 1072. (5) Shuman, M. S.;Collins, 6. J.; Fitzgerald, P. J.; Olson, D. L. I n "Aquatic and Terrestrial Humic Materials"; Chrlstman, R. F., Gjesslng, E. T., Eds.; Ann Arbor Press: Ann Arbor, M I , 1983; pp 349-370. (6) Shlbata, S. I n "Chelates in Analytical Chemistry, Vol. 4"; Flaschka, H. A,, Barnard, A. J., Jr., Eds.; Marcel Dekker: New York, 1972; p 116.
1107
(7) Ferry, J. D. "Viscoelastlc Properties of Polymers", 3rd ed.; Wiley: New York, 1980; Chapter 4. (8) Schwarzl, F.; Staverman, A. J. Physica (Amsterdam) 1952, 7.9, 791-798. (9) Connors, K. A. Anal. Chem. 1975, 4 7 , 2066-2067. (10) Connors, K. A. Anal. Chem. 1979, 57, 1155-1160, (11) Widder, D. V. "The Laplace Transform"; Princeton University Press: Princeton, NJ, 1946. (12) Bellman, R.; Kalaba, R. E.; Lockett, J. "Numerical Inversion of the Laplace Transform"; American Elsevier: New York, 1966. (13) Beck, J. V.; Arnold, K. J. "Parameter Estlmation in Engineering and Science"; Wiley: New York, 1977; p 126. (14) Karger, B. I-.;Snyder, L. R.; Horvath, C. "An Introduction to Separation Science"; Wlley: New York, 1973; p 147. (15) Reich, R. M. Anal. Chem. 1971, 4 3 , 85A-97A. (16) Saar, R. A.; Weber, J. H. Environ. Sci. Techno/. 1982, 76,510A517A.
RECEIVED for review November 4,1982. Accepted February 7, 1983.
Fractional Separation of Organic and Inorganic Tin Compounds and Determination by Substoichiometric Isotope Dilution Ana Iysi:; Hisanorl Imura and Nobuo Suzuki" Department of Chemistry: Faculty of Science, Tohoku University, Sendal, 980 Japan
Tributyltln( IV), dibutylltln( IV), butyltln( IV), and lnorganlc tin( I V ) can be separated from each other by halide extraction with benzene. Dlbutylitin( IV), butyltln( IV), and inorganlc tin( I V ) are substoichiometrlcallydetermined vla complexatlon with sallcylldeneamino-2-thlophenoi in benzene. Trlbutyitln( I V ) can be determined by applylng the substolchiomeiry to one of the decomposlltlon products by bromine treatment of the mother compound. The subsiolchlometric determination of dlbutyltin( I V ) and biutyltln(I V ) In a commercial organotin chemical and B poly(vinyl chloride) sheet Is demonstrated. The reiatlve standard deviation of the substoichlometric determination is nearly 1% at the 0.1-1 mg level.
required. Simple measurement of the radioactivity of the substoichiometric extract is enough for the final determination. The substoichiometric isotope dilution method has been applied to the speciation of different valence states of antimony (4)and arsenic (5) and of methylmercury and inorganic mercury (6). We have already reported the substoichiometric determination of inorganic tin in environmental samples (7) and in various organotin compounds (8)via the complexation with salicylideneamino-2-thiophenol(SATP) in a nonaqueous medium. In this paper, a preliminary separation of butyltin(IV), dibutyltin(IV), and tributyltin(1V) and the substoichiometric isotope dilution analysis for these tin species are investigated and applied to a commercial organotin chemical and PVC sample.
Various orgaaotin compounds have been used in industry and agriculture; for instance, dibutyltin dilaurate is commonly used as a stabilizer for poly(viny1 chloride) (PVC), tributyltin polyacrylate (tributyltin polymer) in antifouling paints for ship bottoms, and bis(tributy1tin) oxide as a fungicide. These compounds on the market often contain other butyltin homologues with different numbers of butyl groups. Toxicity of the organotin compounds is remarkably different from one another depending on the number of alkyl groups. Speciation of individual organotin and inorganic tin should be developed. Only a few analytical methods (1-3) have been proposed for inorganic tin and a series of organotin compounds from monot o trialkyltin, but the following disadlvantages should be pointed out fo'r these methods: (a) decomposition and evaporation lose of tin compounds during the operation must be considered, (b) quantitative recovery of the compounds of interest must always be accomplished, and (c) calibration curves for all the compounds are required. Substoichiometry combined with the isotope dilution principle seems to be suitable for the speciation of alkyltin compounds by (consideringthe following advantages: quantitative recovery of each species and calibration curves are not
EXPERIMENTAL SECTION Materials and Apparatus. Radioactive Butyltin(IV) and Dibutyltin(1V). Carrier-free tin-113 produced by the nuclear reaction 1151n(p,3n)1'3Sn with 40-MeV protons at Tohoku University Cyclotron and Radioisotope Center was isolated from the irradiated indium oxide by an iodide-extraction method (7,8). Anhydrous tin(1V) chloride labeled with I13Sn was prepared by contacting purified '13Sn iodide with anhydrous tin(1V) tetrachloride. The labelling of different butyltin compounds was achieved by a redistribution reaction (9) under various conditions. Butyltin(1V)chloride labeled with l13Sn was prepared by stirring 0.4 mL of tetrabutyltin with 0.2 mL of labeled tin(1V) chloride for 3 h at 100-110 O C . Dibutyltin(1V)chloride labeled with I13Sn was prepared by the similar treatment except heating conditions were at 220 "C for 4 h. The labeled butyltin compounds were purified by halide extraction into benzene (cf. Figure 2). The purity of the labeled compounds was tested by silica gel thin-layer chromatography (IO) with a developing solvent of butanol-acetic acid-water (10:2:5). The carrier concentration of the labeled compound was accurately determined by the substoichiometric isotope dilution method developed here. Radioactive Tributyltin(IV). Radioactive tributyltin(1V) was prepared directly by the photonuclear reaction 11sSn(y,n)117mSn.
0003-2700/83/0355-1107$01.50/00 1983 American Chemical Society
1108
ANALYTICAL CHEMISTRY, VOL. 55, NO. 7,JUNE 1983 ISamDle s o l u t i o n s in C,H,
3
I
s p i k e r a d i o - t i n species wash w i t h d i l APSO4 C1I
2
+
1 c
,
a d j u s t I - concn, l e x t m t w i t h C,H6
s o subs t o ich i ornet r i c s e p a r a t i o n o f Sn
-1
USnEril
-2
Y-count i n s !substoich&ly separate w i t h SATP
-3
subs t o i ch iome t r ica 1 1Y SeDarate w i t h SATP
1
IOrg.4 SnI,
v-counting
subs tolchiome t r ic a l l Y
separate w i t h SATP ukount ins
Figure 1. Scheme of substolchiometric speciation of a series of tin compounds.
A 0.5-mL portion of bis(tributy1tin) oxide in a quartz test tube was irradiated for 6 h with 30-MeV bremsstrahlung at the Tohoku University linear electron accelerator. The irradiated compound was purified by chloride extraction with benzene. The purity of the labeled compound was checked by y-ray spectrometry and thin-layer chromatography. Other materials and apparatus were the same as those used previously (7, 8). Procedure. The recommended procedure for the speciation of various tin species is schematically summarized in Figure 1. In this model system the procedure starts from the sample solution in benzene containing all the tin species obtained, if necessary, by halide extraction. The analytical procedure for each tin species is separately described below. TributyZtin(ZV).The sample solution was washed several times with 2 M sulfuric acid containing 0.001 M sodium chloride. The benzene phase (Org 1)containing only tributyltin(1V) chloride was shaken for 30 min with an equal volume of 2 M sulfuric acid-2 M sodium bromide-0.1 M sodium bromate solution to decompose tributyltin(1V) compound. To the aqueous phase 10% ascorbic acid solution was added to reduce bromine completely, and this aqueous solution (Aq 5) was subjected to the substoichiometric determination of inorganic tin(1V). Dibutyltin(ZV). The aqueous phase (Aq 1)was adjusted to be 2 M sulfuric acid and 0.1 M sodium chloride, and shaken with 10 mL of benzene for 1 min. To a 5-mL portion of the benzene phase (Org 2), 1 mL of SATP solution in ethanol containing a substoichiometric amount of SATP (-5 X 10" M) together with 1%ascorbic acid and 0.5 mL of 10% pyridine solution in ethanol were added, allowed to stand for 30 min, and shaken for 3 rnin with 10 mL of pH 6.25 buffer solution containing 2.0 X M 8-quinolinol-5-sulfonate(QS). A 3-mL portion of the organic phase was taken and allowed to stand for 18 h to achieve the radioactive equilibration. The y-activity was measured with an NaI(T1) scintillation counter set. Butyltin(ZV). The aqueous phase (Aq 2) was adjusted to be 2 M sulfuric acid and 2.2 M sodium bromide and then shaken with 10 mL of benzene for 1min. Only butyltin(1V)was extracted into the organic phase as bromide (Org 3). A 5-mL portion of the benzene phase was mixed with 1 mL of SATP solution, containing a substoichiometricamount of SATP and 1%ascorbic acid and 0.1 mL of 10% pyridine solution, and the mixture was allowed to stand for 10-30 min and shaken for 3 min with 10 mL of acetate buffer solution (pH 5.6) containing 5.0 X M ethylenediaminetetraacetate (EDTA). The y-activity of the organic phase was measured as described above. Inorganic Tin(ZV). The aqueous phase (Aq 3) containing only inorganic tin(1V) was adjusted to be 2 M sulfuric acid and 1 M sodium iodide and shaken with benzene. To a 5-mL portion of the benzene phase (Org 4) a substoichiometric amount of SATP solution and 0.1 mL of 10% pyridine solution were added, and the mixture wm shaken for 1h with 5 mL of pH 3.9 buffer solution
I O ~ I Y - I / mol/dm'
Figure 2. Distribution ratio of dibutyltin(1V) and butyltin(1V) in halide M, (c, d) BUS^'^] extraction systems: (a, b) [ B U , S ~ ' ~=] 3.77X = 3.99 X lo4 M; (a, c) bromide system, (b, d) chloride system; shaking time = 1 min.
containing 1X lo4 M tartrate. The y-activityof the organic phase was measured (8).
RESULTS AND DISCUSSION Halide Extraction of Butyltin Compounds. Extraction of butyltin compounds in the iodide system has been reported (8). The extraction behavior of dibutyltin(1V) and butyltin(IV) in the chloride or the bromide system is shown in Figure 2 where the distribution ratio (D)of butyltin compounds is given as the ratio of concentration of the compound in the organic phase to that in the aqueous phase. Inorganic tin(1V) is not extractable with benzene from the chloride or the bromide medium. The distribution ratio of tributyltin(1V) chloride is as high as 102.6even in the absence of extra halide ions in the aqueous phase, and any reasonable dependency on halide concentration cannot be shown in Figure 2. The extractability of tin species in all the systems increases in the order Sn(1V) < BuSn(1V) < Bu2Sn(IV)< Bu3Sn(IV),and also the extractability of dibutyltin(1V) and butyltin(1V) in different halide systems increases in the order chloride < bromide < iodide. These orders seem to be consistent with the increase in the size of tin species as well as the counter halide ion. Mutual separation of these tin species involving inorganic tin(1V) may be readily achieved by selecting an appropriate halide system; that is, only tributyltin(1V) is extractable from very low concentrations of chloride, and dibutyltin(IV), butyltin(IV), and inorganic tin(1V) are selectively extractable from chloride, bromide, and iodide media, respectively. Substoichiometric Determination of Butyltin(1V) and Dibutyltin(1V). The key step for the substoichiometric determination is the reproducible complexation of tin species of interest with a substoichiometric amount of SATP in benzene phase followed by washing out of an excess of free tin species. When a 5-mL portion of (1.4-2.2) X M radioactive butyltin(1V) or radioactive dibutyltin(1V) in benzene M SATP and 0.1-0.5 mL was mixed with 1 mL of 2.0 X of 10% pyridine, the butyltin(1V)- and dibutyltin(1V)-SATP complexes were quantitatively formed on standing for over 10 min. Preliminary experiment showed that the excess of butyltin(1V) and dibutyltin(1V) was not completely back-extracted from the benzene phase by simple shaking with an acetate buffer solution. Hence the back-extraction with a masking agent was examined. As shown in Table I the observed radioactivity of butyltin(1V) in the organic phase is constant after shaking with EDTA and equal with the radioactivity expected by assuming the equivalence reaction with a substoichiometric amount of SATP added here, but EDTA is not effective for removal of an excess of dibutyltin(1V). An excess of dibutyltin(1V) can be readily removed with 8-
ANALYTICAL CHEMISTRY, VOL. 55,
8
1500
,
NO. 7, JUNE 1983
1109
I
500 Y
>
"
Y
4
0 0
2
4
6
8
1
0,4
0
0
Flgure 3. Effect of pH of washing solutions on substoichiometric separations: (a) [BuSnrV] := 2.2 X M, [SATP] 4.0 X M, M, [SATP] = M; (b) [BU,S~'~]= 4.8 X [EDTA] = 5.0 X 1.0 X M, [as] = 2.0 X M.
EDTA
activity of organic phase/cpm BuSnIV Bu,SnIV
1.6
20
/ mg
loo
r
(I
2867 614
0,2 0..5
6241 6249
605
l"0
QS
1.2
Flgure 4. Reproducibilityof substoichiornetric separation. The abscissa is the amount of each butyltin in benzene solution obtained by halide extraction: (a) BuSn", [SATP] = 4.0 X lo4 M, [EDTA] = 5.0 X I O 3 M, pH 5.61; (b) Bu,SnIV, [SATP] = 1.0 X M, [QS] = 2.0 X M, pH 6.52.
Table I. Effect of a Masking Agent on Substoichiometric Separation masking agent/ lo-? M
0.8
BuSn(lV) or Bu2Sn(lV) token
PH
0.5 1,o 2.0 5.0
3610 1655 1214 1209
expected value
609
20
0
1215
40
60
Shaking time / mln
a [BuSnBr,] = 2.2 x M, [SATP] = 4.0 x M, pH 5.6. [Bu,SnCl,] := 4.9 x M, [,SATPI = 1.0 x M, pH 5.2-5.8. See text.
Flgure 5. Decornpositlon proflie of tributyltin(1V) in benzene with bromlne: (a) BU,S~'~,(b) Bu,Sn", (c) BuSnIV,(d, e) Sn"; initial concentration of Bu,Sn'', 1.4 X IOT3 M; decornposltion reagents in an aqueous phase, (a-d) 3 M NaBr-0.05 M NaBr0,-2 M H2S04,(e) 2 M NaBr-0.1 M NaBr0,-2 M H2S04.
quinolinol-5-sulfonate. This may be understood from the fact that 8-quinolinol (HOX) forms a stable chelate with dibutyltin(1V) as BuzSn(OX)z (11). Effect of pH for the back-extraction of an excess of butyltin species is shown in Figure 3, where w constant and an equivalent amount of butyltin(1V) or dibutyltin(1V) chelated with added SATP remains in the organic phase after washing a t pH 5-7. In the substoichiometry an exactly equal amount of the species of interest must be separated from !solutionscontaining its varying quantities. The present procedure was applied to a series of solutions containing different amounts of butyltin(n7) or dibutylitin(n7). Figure 4 shows that the radioactivity of the organic phase increases with increase in the amount of butyltin(1V) or dibutyltin(1V) up to the equivalence point corresponding to a 1:l ratio of butyltin(1V) or dibutyltin(1V) to SATP. Beyond this region, under the substoichiometric conditions, a constant amount of butyltin(1V) or dibutyltin(n7) remains in the organic ]phase and the relative standard deviation (RSD) in the clonstant region is as little as 0.8%.
The accuracy and precision of the proposed method were evaluated by analyzing a synthetic mixture; viz., dibutyltin(IV), butyltin(IV), and inorganic tin(1V) in the presence of a large amount of tributyltin(n7) were successively determined according to the recommended scheme shown in Figure 1. As summarized in Table 11, the RSD of 0.4-2.1% is very satisfactory, and the determined value is consistent with the amount taken. This result also shows that an unfavorable isotopic exchange among these tin species does not occur under the given conditions, e.g., a t room temperature and ordinary operation time. Substoichiometry for Tributyltin(1V). Trialkyl- and triaryltin(1V) usually form five-coordinate complexes with unidentate ligands such as pyridine (12) but do not form stable chelate compounds with 8-quinolinol (13) and 1 , l O phenanthroline and 2,2'-bipyridine (14). In our preliminary experiment, the chelate formation of tributyltin(1V) with
Table 11. Successive Determination of Dibutyltin(IV), Butyltin(IV), and Tin(1V) in Tributyltin Chloridea
tin species
content,a Ilg
activity from spike a,, cpm
Bu,SnrV
461
586
904
BuSnIV
140
214
1024
57.8
a
radioactive tin species spiked, M,, gg
64.2
Synthetic mixture containing 51 mg af Bu,SnCl.
10698
activity from test sample a , cpm
.
506 507 501 622 6 27 632 5670 5676 5655
found M,pg
mean value
459 458 471 139 136
463 i 7 RSD = 1.5%
i. o , &
136 c 3 RSD = 2.1%
133
56.9 56.8 57.2
Calculated from M = M,(a,/a - 1).
57.0 k 0.2 RSD = 0.4%
1110
ANALYTICAL CHEMISTRY, VOL. 55, NO. 7, JUNE 1983
Table 111. Substoichiometric Determination of Dibutyltin(1V) in Commercial Tributyltin Chloridea
a
sample taken, g
radioactive Bu,SnIV spiked, mg
0.201 8
3.42
1128
0.2096
3.42
1128
Mean value
i:
u =
activity from spike, CPm
activity from test sample, cpm
Bu,SnIV found, mg
concn,
54 8 552 553 543 54 1 541
3.62 3.57 3.56 3.68 3.71 3.71
1.80 1.77 1.76 1.76 1.77 1.77
%
1.77 * 0.01%, RSD = 0.6%.
Table I V . Substoichiometric Determination of Butyltin( I V ) in PVC Sheeta
a
sample taken, g
radioactive BuSn spiked, pg
activity from spike, cpm
0.104 16
660
25 726
0.103 44
961
23 612
0.104 65
961
23 612
Mean value
i.
(I
= 0.614
f
+
amt of BuSn found, k g
concn,
1 2 943 1 3 132 1 2 825 14 250 14 428 14 193 13 961 14 248 14 269
652 633 664 631 61 2 638 664 632 6 29
0.626 0.608 0.638 0.610 0.591 0.616 0.635 0.603 0.601
%
0.016%, RSD = 2.6%.
SATP was not observed. Therefore, a following modification was introduced: tributyltin(1V) is separated from other tin species after addition of its radioactive spike and then decomposed with bromine. An example of decomposition profile is shown in Figure 5. The following decomposition processes can be considered Bu3SnBr Br, Bu2SnBr2 BuBr (1) Bu2SnBr2 Br2 BuSnBr, BuBr (2) SnBr, BuBr BuSnBra Br2 (3) Now the substoichiometry can be applied to an appropriate tin species thus formed. As known, the complete recovery of a species of interest is not necessary in the substoichiometry, and this also means that the complete and quantitative decomposition of tributyltin(1V) to a single species is not necessary for the substoichiometric analysis. Here inorganic tin(1V) was subjected to the substoichiometry because of its simple separation from other organic species. Reliability of the present procedure was simply confirmed by comparing the reproducibility of the substoichiometric extracts of inorganic tin(1V) as follows; inorganic tin(1V) formed by the decomposition of radioactive tributyltin(1V) (ca. 6.9 mg taken) with bromine was substoichiometrically extracted with 1.5 X 10" M SATP. The reproducibility was as good as 1.2% RSD for six determinations irrespective decomposition yield of inorganic tin(1V). This clearly shows tributyltin(1V) can be determined with high precision via the substoichiometry for one of the decomposition products. Substoichiometric Determination of Dibutyltin(1V) Impurity in a Commercial Organotin. The present procedure was applied to the determination of dibutyltin impurity in a commercial tributyltin chloride (more than 98% purity according to the supplier). The results are summarized in Table I11 and the high precision of 0.6% is again clear. The absence of tin impurities other than dibutyltin(1V) species was ascertained by thin-layer chromatography. The relatively large amount of dibutyltin(1V) found in this sample may be a byproduct in the preparation of tributyltin compound. Determination of Butyltin(1V) in PVC. Poly(viny1 chloride) contains about 1-3% butyltin compounds as a sta-
+ +
activity from test sample, cpm
--
+
+
+
bilizer. About 0.1 g of a sheet sample (10 x 17 mm) was dissolved in 1 mL of tetrahydrofuran, and then 2 mL of the radioactive butyltin(1V) in benzene was added and allowed to stand overnight. This sample solution was subjected to the substoichiometric determination. The results are shown in Table IV. The determined value, 0.614 f 0.016%, is nearly consistent with the nominal content calculated from the added amount of butyltin tri(isooctylthioglyco1ate) in synthetic preparation of the PVC sheet, ca. 0.63% as butyltin(1V). The lower limit of the substoichiometric determination is principally governed by the reliability of the substoichiometric extraction and of the radioactivity measurement, and the latter is related with the specific activity of the spike (labeled compound). In our present experiment we could not obtain a spike with high specific activity mainly due to technical problems in the synthesis of radioactive organotin compounds, but this limitation, of course, can be improved by introducing more skillful techniques, e.g., very small scale synthesis. In the present paper we proposed an idea of the speciation of inorganic tin and a series of butyltin compounds, but for more general application of the substoichiometry to many different organometallic compounds, a combination with liquid chromatography will be efficient. In conclusion, the substoichiometric isotope dilution analysis developed here is a powerful method for the accurate and precise determination of metal-involving species a t minor concentration levels. These advantages may be drawn from the fact that the present method does not require complete recovery and any calibration standards.
ACKNOWLEDGMENT The authors wish to express their appreciation to Kyodo Yakuhin Co., Ltd., for kindly supplying the materials. Registry No. Sn, 7440-31-5;SATP, 3449-05-6;Brz, 7726-95-6; Bu3SnC1, 1461-22-9;PVC, 9002-86-2. LITERATURE CITED (1) Soderquist, C. J.; Crosby, D. G. Anal. Chem. 1978, 50, 1435-1439. (2) Braman, R. S.;Tompkins, M. A. Anal. Chem. 1979, 57, 12-19. (3) Hodge, V. F.; Seldel, S. L.; Goldberg, E. D. Anal. Chem. 1979, 57, 1256- 1259.
Anal. Chem. 1983, 55, 1111-1115 (4) Kanda, Y.; Suzukl, N. Radlochem. Radloanal. Lett. 1979, 3 7 , 183-189. (5) Kanda, Y.; Suzukl, N. Radiochem. Radloanal. Lett. 1979, 39, 221-231. ( 6 ) Kanda, Y.; Suzuki, N. Anal. Chem. 1960, 52, 1672-1675. (7) Imura, H.; Suzuki, N. Talanta 1981, 28, 73-79. (8) Imura, H.;Suzukl, N. Anal. Chlm. Acta 1981, 126, 199-205. (9) Ingham, R. K.; Rosenberg, S . D.; Gilman, ti. Chem. Rev. 1960, 60, 459-539. (IO) Herold, B.; Droege, I(. H. Fresenius' Z . Anal. Chem. 1969, 245, 295-299.
1111
(11) Tanaka, T.; Kornura, M.; Kawasaki, Y.; Okawara, R. J . Organomet. Chem. 1964, 1 , 484-489. (12) Hulme, R. J . Chem. SOC.1963, 1524-1527. (13) Roncucci, L.; Faraglla, G.; Barbieri, R. J . Organomet. Chem. 1964, I , 427-430. (14) Beattle, I. R.; Mcqullliam, G. P. J . Chem. SOC. 1983, 1519-1523.
for review
277
1982* Accepted February
'7
1983.
Determination of Hydantoins in Condensate Water from Lignite Gasification Edwin S. Olson," John W. Diehl, and David J. Miller U S . Department of Energy, Grand Forks Energy Technology Center, Box 8213, University Station, Grand Forks, North Dakota 58202
A method for the characterization of the nonsolvent extractable hydantoins In condensate water from the slagging fixed bed gasification of llgnlte was developed. The water was treated with activated carbon and the hydantoins were extracted from the carbon with boiling alcohol. A number of 5,5-diaikyl- andl 5-alkylhydantoins were separated by gas chromatography on a polar fused silica capillary column and characterized by comparison of their mass spectra with known standards and by matching retention Indexes. For compounds with low initensity molecular ions, chemical ionization with methane was used for identification. The 1,3dimethyl derivatives of the hydantoins were prepared and chromatographod on a nonpolar capillary column to provide further confirmatlon of the presence of the hydantoins.
The existence of polar nonsolvent extractable compounds in the condensaite water from the slagging fixed bed gasification of lignite has been known for some time. Only recently have the major constiituents of the condensate water been identified ( I , 2). This paper describes the characterization of the various alkylhydantoins found in water from the GFETC gasifier. Condensate water which had been extracted three times with methylene chloride was treated witlh activated charcoal. The filtered charcoal was then extracted with boiling ethanol. Evaporation of the ethanol gave a white solid in a yield of I .5 g/L of condensate water. The white solid was analyzed by gas chromagraphy, using a polar wall-coated phase (Superox-FA, AT-1000) fused silica capillary column. GC/MS data were obtained in both E1 and CI modes for the components of this mixture from the ethanol extraction of the charcoal. Retention index matching with reference hydantoin standards was carried out with a flame ionization detector. Dimethyl derivatives which exhilbit more intense molecular ions than the underivatized hydantoins were prepared and analyzed by GC/MS on a nonpolar capillary column.
EXPERIMENTAL SECTION The condensate water was produced from gasification of Indian Head lignite in the GFETC slagging fixed bed gasifier at 300 psig with oxygen feed rates of 6000 scfh (standard cubic feet per hour)
and an oxygen to steam molar ratio of 0.9 to 1.0 (3). The product gas was cooled from about 160 to 50 "C in a spray washer, which circulates the condensed water into contact with the hot gas. After a residence time of about 2 h, the liquor was fed to a tar water separator (50 "C) where the water had a residence time of 6-7 h. Condensate water (500 mL) was stirred for 2 h with 10 g of charcoal (Pittsburgh Activated Carbon, Calgon 12 X 40) which had been ground in a mortar and pestle. The charcoal was filtered by gravity and the pH of the filtrate was adjusted to 2.0 by adding HCl. The acidified filtrate was stirred with a second 10 g of charcoal. Filtration was again performed and the charcoal was combined with that obtained earlier and extracted with boiling ethanol (300 mL) for 30 min. Evaporation of the ethanol on a rotary evaporator gave a residue. If the condensate water had been previously extracted with methylene chloride, diisopropyl ether, or methyl isobutyl ketone, the residue contained only a very small amount of phenols and weighed about 0.75 g. If unextracted condensate water was treated with charcoal, then 2.5-3 g of phenolics was also present in the residue. A Hewlett-Packard 5880A gas chromatograph with FID detection and on-column injection (0.2 fiL) was used for the retention index studies. 'The column was a 25-m Superox-FA (AT-1000) fused silica capillary with 0.32 mm i.d. and 0.3-fim film thickness. The carrier was ultrahigh-purity hydrogen passed through an oxygen trap and a molecular sieve-Drierite tube and set at a flow rate of 2 mL/min (41 cm/s) at 260 "C. Nitrogen was used as detector make-up gas. The residue or hydantoin standards were dissolved in methanol. Multilevel oven temperature heating rate program was as follows: initial temperature, 60 "C; program heating rates, 30 "C/min to 85 "C, 0.5 "C/min to 100 "C, 1 "C/min to 200 "C, and 1.5 "C/min to 260 "C. Although a multilevel heating rate program was used, the retention indexes remained constant as long as the head pressure on the column was not changed. The GC/MS data were obtained with a Hewlett-Packard5985B and a 25-m Superox-FA (0.25 mm id.) fused silica capillary column (on-columninjection) for the underivatized hydantoins. Hydrogen carrier at 1mL/min was used. Electron energies of 70 eV for E1 and 200 eV for CI modes were used. Source temperature was 200 "C, scan rate was 267 amu/s, and mass range was 40-400 amu. Methane was the CI reagent gas. 5,5-Dimethylhydantoinwas purchased from Aldrich Chemical Co. Other hydantoins were synthesized from the cyanohydrin by the method in Vogel ( 4 ) . Methylation of the hydantoins was carried out by use of methyl iodide in a pH 13 buffer (5). A 60-m DB5 fused silica capillary
This article not subject to U S . Copyright. Published 1983 by the American Chemical Society
