Anal. Chem. 1088, 6 0 , 316-319
316
plitude versus incident laser power per pulse is linear over the range 1-3.3 mJ. A log-log plot of amplitude versus absorptivity results in a slope of -0.5. Both the frequency maximum amplitude and raw signal peak height were plotted. The reason for the nonlinearity is unclear at this time. It is possible that the equation derived by Tam and Patel for low-absorbance liquids is not entirely applicable to this system. It is also possible that the experimental method used to determine amplitude as a function of concentration is inherently insensitive to concentration changes due to the amount of solute partitioned into the stationary phase. Even so, the limit of detection as defined by a signal to noise ratio of 3:l is in the low nanogram range for Cr(0CHJTPP. The effects of flow rate and laser diameter on the acoustic waveform were also investigated. No significant perturbations of the waveform occurred with flow rates up to 0.3 mL/min. Restricting the laser beam diameter has the effect of decreasing amplitude but does not alter the waveform. A plot of the amplitude of the frequency maximum versus position on the column shows a complicated, yet predictable, relationship. Frequency dependence on column position was found to be slight, varying from 28 to 30 kHz over 16 cm for the packed column. In conclusion, these initial results demonstrate that photoacoustic spectroscopy may be employed as an on-column detection method for microbore (packed column) high-performance liquid chromatography. The benefits of on-column detection have been detailed elsewhere (9, 13, 14,17). Until
now, however, on-column detection has been applied primarily to open tubular capillary chromatography due to the scattering effects expected for packed columns. Since photoacoustic spectroscopy is not significantly affected by scattered light, it is well-suited for on-column detection when using packed column chromatography.
LITERATURE CITED Whlte, R. M. J . App. Phys. 1983, 3 4 , 3559. Patei, C. N.; Tam, A. C. Rev. Mod. Phys. 1981, 5 3 , 517. Hutchins, D. A.; Tam, A. C. I E E Trans. 1988, UFFC-33, 429. Rosencwaig, A.; Gersho, A. J . Appl. Fhys. 1976, 4 7 , 64. Lei, H. M.; Young, K. J . Acoust. SOC.Am. 1982, 72, 2000. Lai, E. C.; Su,S.Y.; Voightman, E.; Winetordner, J. D. Chromstograph& 1982, 15, 645. Cda, S.; Sawada, T. Anal. Chem. 1981, 53, 471. Lal, E. C.; Chan, L. 6.; Chan, L. L. Anal. Chem. 1983, 5 5 , 2441. Gelderloos, D. G.; Rowien, K. L.; Birks. J. W.: Avery, J. P.: Enke, C. G. Anal. Chem. 1986, 5 4 , 900. Poole, C. F.; Schutte, S.A. Contemporary Practice of Chromatogra phy; Eisevier: Amsterdam, 1984. Handbodc of Chemistry and Physics; CRC Press: Boca Paton, FL. Poilard, H. R. Sound Waves In SolMs. Pion, Ltd: London, 1977. Yang, F. HRC CC , J High Resolut , Chromatogr . Chromatogr . Com mun. 1981, 4 , 10211. Guthrie, E. J.; Jorgenson, J. W. Anal. Chem. 1984, 5 6 , 483. Nosaka, Y.; Igarashi, R.; Miiama, H. Anal. Chem. 1985, 5 7 , 92. Voightman, E.; Jorgenson, A.; Winefordner. J. D. Anal. Chem. 1981, 5 3 , 1442. St. Claire, R. L.; Jwgenson, J. W. J . Chromatogr. Sci. 1985, 23, 186.
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RECEIVED for review August 12,1987. Accepted September 30, 1987. This work was supported by a grant from the U.S. Environmental Protection Agency (No. R-810717-01-0).
Speciation of Methyl- and Butyltin Compounds and Inorganic Tin in Oysters by Hydride Generation Atomic Absorption Spectrometry Jennie S. Han and James H.Weber*
Chemistry Department, Parsons Hall, University of New Hampshire, Durham, New Hampshire 03824
Became of the toxicity of tributyltln orlglnating from many antifouling marlne paints, there is much concern about Its Wed on squa#c We and, par#cularty, on shdlllstr. This paper descrtbes speciation of inorganic tin, methyltin compounds, and butyltln compounds from oyster samples. We validated the hydrlde generation atomk absorption spectrophotometric technique by demonstrating ca. 100% recovery from splked samples and by the a-ce of any organotln decomposltlon products. Absolute detectlon limits ( 3 u ) are 1.1-2.5 ng for 0.14 oyster samples (wet weight). This method Is superior to puMlshed techniques because of careful validation, low ilmlts of detectlon, and minimal sample manipulation.
Worldwide use of organotin compounds was ca. 30000 tons in 1982 ( I ) . About two-thirds of total organotin production is dimethyl- and dibutyltin compounds used for stabilization 0003-2700/88/0360-0316$0 1.50/0
of poly(viny1 chloride), but a major environmental concern today is the use of tributyltin compounds in antifouling marine paints ( 2 ) . Tributyltin compounds are extremely toxic to aquatic life a t low nanogram per milliliter concentrations (3-5). Some results for oysters are shell thickening ( 2 ) ,decreased reproductive ability ( 4 ) ,and mortality a t less than 1 ng/mL tributyltin concentration (5). Feeding habits of bivalve molluscs such as oysters are relevant to their health and potentially to that of human consumers. These filter feeders obtain trace metals not only from solution and ingestion of food but also from ingestion of particulate material containing metals. The problem with filter feeding, from the point of the organism and the consumer, is that bivalves ingest particles much faster than they expel them. This behavior leads to storage or bioaccumulation of particles (6). Increasing evidence of the toxicity of organotin compounds to aquatic organisms, especially shellfish, accentuates the need 0 1988 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 60, NO. 4, FEBRUARY 15, 1988
for accurate measurement of their concentrations in biological samples. An appropriate analytical procedure requires quantitative extraction, separation, and quantitation of organotin compounds of interest. The procedure should not break carbon-tin bonds of the organotin compounds in the organism, should result in quantitative or nearly quantitative recovery, and should minimize sample handling. We know of no published procedure that fulfius the above requirements for determination of organotin compounds in oysters. Known methods (3,7,8)have one or more of these three flaws. They either have not been tested for percent recovery and carbon-tin bond cleavage during sample work-up, or require considerable sample manipulation. This paper describes a method for simultaneous extraction of inorganic tin, methyltin compounds, and butyltin compounds from oyster tissue and quantitation by a hydride generation atomic absorption spectrometric (HG-AAS) approach developed by our group (9, IO) and applied to estuarine water (9) and estuarine sediment samples (11). Because of possible carbon-tin bond breaking, researchers must usually develop a new extraction method for each type of environmental matrix. The procedure, which requires a minimum of sample manipulation, recovers methyl- and butyltin compounds quantitatively and without modification from spiked samples of oyster tissue. Despite the low limit of detection (3u) of about 2 ng in 0.1-g oyster samples (wet weight), we measured no butyltin compounds in oysters from the Great Bay Estuary (NH). EXPERIMENTAL SECTION Apparatus and Reagents. The hydride generation atomic absorption spectrophotometric (HG-AAS) technique and most reagents were previously described (9,10). All water was doubly deionized and distilled. Antifoam B silicone emulsion was obtained from J. T. Baker Chemical Co. Standards. Butyltin standards (100 pg of Sn/mL) were prepared by dissolving butyltin chlorides in 10 mL of methanol. Methyltin standards (100 pg/mL) were prepared by taking 10 mL of methyltin chloride stock solutions (1000 pg of Sn/mL), diluting with water, acidifying with 1 mL of 5 M HNO,, and adding water to a 100-mL total solution volume. A standard of inorganic tin (100 pg of Sn/mL) was prepared by dissolving 0.1 g of 99.9% 20-mesh Sn powder (Alfa) in 10 mL of HC1 and adjusting the volume to 1L with water. All standards were stored in Hypo-vials sealed with crimp-on Teflon-lined septa at 4 "C in the dark (9). Operating Procedure. The HG-AAS operating procedure was as described previously (9,IO) with a few exceptions. Before addition of the oyster sample to the generator flask, the stirrer was turned on and one drop of Antifoam B silicone emulsion was added via a Pasteur pipet. Calibration and Limits of Detection. Simultaneous calibration of all standards in the oyster matrix was carried out by doing triplicate measurements on three different concentrations. Standards containing inorganic tin, a mixture of three methyltin chlorides, a mixture of three butyltin chlorides, and triethyltin bromide were injected into the generator flask containing the oyster blank. Detection limits were determined in the oyster matrix by using six replicates. Sample Preparation and Storage. Freeze-dried oyster samples from France originated in the Le Croisic River in the northern part of the Loire Estuary. Oyster samples (Crassostrea uirginica)were collected in Odober 1986 from three locations of the Great Bay Estuary, NH. Oysters were transported to the laboratory in plastic bags. Submersion in seawater during transport was avoided since oysters submerged in seawater open their valves and pump water, releasing waste products. When exposed to air, however, their valves remain closed and their metabolic rate is greatly reduced (12). Preparation of oyster homogenate was done by the United Nations Environment Programme method (12). Oyster shells were scraped of foreign material and rinsed with water, then were pried open and again rinsed with water. Whole oyster tissue was separated
317
Table I. Calibration Curve Data and Limits of Detection of Inorganic Tin and Alkyltin Compounds in the Oyster Matrix compound SnClz MeSnC13 MezSnC12 MeaSnCl BuSnCl, Et3SnBrc BuzSnC12 BusSnCl
slope' x io-' (SD) 0.80 (0.04)
0.46 (0.05) 0.48 (0.02) 0.45 (0.01) 0.49 (0.01) 0.26 (0.01) 0.28 (0.01) 0.10 (0.00)
intercept" x 10-~ (SD) LOD,* ng 0.12 (0.47) -0.07 (0.56) 0.13 (0.18)
0.06 (0.07) 0.13 (0.09) 0.02 (0.13)
0.16 (0.05) -0.07 (0.03)
2.3 1.1 1.1 1.1 1.1 1.1 1.1
2.5
Arbitrary relative units with standard deviation in parentheses. Correlation coefficients of slopes are at least 0.97. All intercepts are zero at the 95% confidence level. *Limit of detection (3a) as Sn for 0.1-g (wet weight) oyster samples. Internal standard. from the shell with Parafilm-wrapped forceps and rinsed with water. Oyster tissue was placed in a 37-mL stainless steel minicontainer and homogenized at 21000 rpm in a Cole-Parmer blender. The minicontainer and blender were encased in a bag of dry ice to prevent heating of samples. The homogenate was placed in poly(methy1pentene) containers and stored frozen t o minimize possible changes by bacterial action. The dry weight/wet weight ratio of oysters from each sampling site was determined by freeze-drying 0.2-, 0.5, and 0.8-g samples of frozen oyster homogenates. Decomposition Study in the Absence of Oyster Tissue. Possible decomposition of methyl- and butyltin compounds in the extracting reagent was tested in duplicate experiments. A solution of 1mL of methanol, 1pg of Sn of an organotin standard, and 5 mL of 8.4 M HCl(7 M final HCl concentration) was placed in a 50-mL glass centrifuge tube. The solution in the capped tube was sonicated at 50/60 Hz in a 60 "C water bath for 1h and then diluted to 10 mL with water in a volumetric flask. A 0.2-mL aliquot was analyzed by using the HG-AAS technique. Methyland butyltin compounds were quantified by comparison to organotin standards injected directly into the generator flask containing the reagent blank of methanol, HCl, and water. Recovery from Spiked Oyster. Recovery of methyl- and butyltin compounds from the oyster matrix was done in triplicate by using spiked samples containing two amounts of Sn. In a capped 50-mL glass centrifuge tube, 0.2 g of the frozen oyster homogenate, 1 mL of methanol, and 0.2 pg of Sn of an organotin standard were equilibrated for 1h and then diluted to 10 mL with water in a volumetric flask. The spiked sample was then processed by adding 5 mL of 8.4 M HC1 and sonicating at 50/60 Hz in a 60 OC water bath for 1 h. A 1-mL aliquot of the spiked sample was analyzed by HG-AAS. The procedure was repeated by using 0.2 pg of Sn of an organotin standard spiked into the sample and analyzing 3-mL aliquots. Methyl- and butyltin compounds were quantified by comparison to organotin standards injected into the generator flask containing the oyster blank of oyster homogenate, extractant, and water. Great Bay Estuary Oyster Samples. In triplicate experiments 1 mL of methanol and 5 mL of 8.4 M HCl were added to 0.5 g of frozen oyster homogenate in a 50-mL glass centrifuge tube. The mixture was sonicated at 50/60 Hz in a 60 "C water bath for 1h and then diluted to 10 mL with water in a volumetric flask. Sample aliquots of 2 mL were analyzed by HG-AAS. Methyland butyltin compounds were quantified by using 2 pL of 9.3 ng of Sn/pL triethyltin bromide as an internal standard. Appropriate reagent blanks were analyzed in a similar fashion. Oyster Samples from France. Since these samples were freeze-dried and the dry weightlwet weight ratio is ca. 0.2, extractions were done on 0.1-g samples. Six replicate experiments and reagent blanks were done as described above for Great Bay Estuary samples. RESULTS Calibration Curves a n d Limits of Detection. Table I summarizes calibration curve data and limits of detection for inorganic tin, triethyltin, methyltin compounds, and butyltin
318
ANALYTICAL CHEMISTRY, VOL. 60, NO. 4, FEBRUARY 15, 1988
Table 11. Recovery of Methyl- and Butyltin Compounds from Extractant in the Absence of Oyster Tissue and from Spiked Oyster Tissue % mean recovery
from extractant"
compound
(SD)
MeSnC1, Me2SnC1, Me3SnCl BuSnC13 Bu2SnC12 Bu3SnCl
96 (1) 99 (5) 102 (7) 103 (7) 104 (8) 101 (6)
compound % mean recovery (SD)*
low spike
high spike
99 (9) 105 (5) 98 (4) 94 (1) 104 (4) 93 (12)
103 (14) 96 (3) 113 (6) 99 (18) 94 (5) 96 (15)
"Mean of duplicate determinations with standard deviation in parentheses. Recovery from extraction procedure in absence of oyster tissue. *Mean of triplicate determinations with standard deviation in parentheses. Compounds were added in amounts of 0.02 wg of Sn/0.2 g of oyster (wet weight) for low spike, and in amounts of 0.2 fig of Sn/0.2 g of oyster (wet weight) for high spike. Table 111. Concentrations of Inorganic Tin and Monomethyltin in Great Bay Estuary Oystersnjb sample location'
TRISnd (SD)
Nannies Island Oyster River Piscataqua River
540 (38) 650 (22) 750 (66)
Table IV. Concentrations of Inorganic Tin and Butyltin Compounds in French Oyster Samplea
MeSn3+ (SD) MeSn/total Sn 98 (9) 95 (17) 120 (19)
0.15 0.13 0.14
nMean of triplicate determinations in ng of Sn/g of oyster (dry weight) with standard deviation in parentheses. The dry weight/ methyltin and all butyltin wet weight ratio is ca. 0.20. compounds not detected. 'Exact location of sites available on reauest. dTRISn is total recoverable inorganic tin. compounds. Relative sensitivities from calibration curve slopes are TRISn > BuSn3+ 2 MezSn2+1 MeSn3+ 1 Me3Sn+ > Bu2Sn2+I Et3Sn+ > Bu3Sn+. TRISn is total recoverable inorganic tin. The limit of detection (3a)(13)in the reagent blank for 0.1-g oyster samples (wet weight) is 2.3 ng (as Sn) for inorganic tin, 2.5 ng (as Sn) for tributyltin, and 1.1ng (as Sn) for all other methyl- and butyltin compounds. All future discussion involving concentrations of organotin compounds will be on the basis of weight of tin.
Decomposition Study in the Absence of Oyster Tissue. Duplicate determinations of controls showed no decomposition of methyl- or butyltin compounds subjected to conditions of 7 M HC1 and sonication at 60 "C for 1 h. Recoveries ranged from 96% to 104% (Table 11). Recovery from Spiked Oyster. Table I1 shows percent recoveries for low (0.02 pg/0.2 g of oyster) and high (0.2 pg/O.2 g of oyster) spikes of methyl- and butyltin compounds in oyster tissue subjected to the extraction conditions. Recoveries, which were corrected for organotin in the oyster, ranged from 93% to 113% and no decomposition products occurred for either the low or high spike. Since the recoveries were quantitative, we did not correct levels measured in the oyster samples. Great Bay Estuarine Oyster Samples. Table I11 shows that TRISn varied from 540 to 750 ng/g of oyster (dry weight) and monomethyltin ranged from 95 to 120 ng/g of oyster for Great Bay Estuary samples. Highest concentrations of TRISn occurred in oysters from the Piscataqua River followed by those from the Oyster River and Nannies Island in the Great Bay. We did not detect other methyltin compounds or any butyltin compound. French Oyster Sample. The freeze-dried oyster sample from France (Table IV) contained only 40 ng/g of oyster (dry weight) total recoverable inorganic Sn (TRISn), and no methyltin compounds. These oysters contain extremely high concentrations of butyltin compounds that ranged from 2200
concn, ng/g (SD)
TRiSnb BuSn3+ Bu2Sn2+ Bu3Sn+
40 (25) 580 (42) 840 (140) 2200 (370)
OMean of six replicate determinations in ng of Sn/g of oyster (dry weight) with standard deviation in parentheses. Methyltin compounds were not detected. bTRISn is total recoverable inorganic tin.
ng/g oyster for tribyltin to 580 ng/g oyster for monobutyltin.
DISCUSSION Development of Methodology. A valid method for speciation of methyl- and butyltin compounds in oyster tissue has several requirements. (1)Since oysters digest and accumulate trace metals in their organs, the tissue must be totally dissolved. (2) Methyl- and butyltin compounds must not undergo loss or addition of alkyl groups. (3) There must be essentially quantitative recovery of spiked alkyltin samples at reasonable levels. The following paragraphs discuss these points. Extraction conditions of 7 M HC1 and sonication at 60 "C for 1 h completely dissolved the oyster tissue to yield a clear yellow-orange solution. Heating and sonicating greatly facilitated the digestion. Higher temperature, higher HC1 concentration, and longer heating times resulted in loss of alkyl groups from some alkyltin compounds. After finding an effective extractant to digest the tissue, we tested for possible loss of alkyl groups from methyl- and butyltin compounds under the extraction conditions in the absence of oyster tissue (eq 1). For example, decomposition R,SnCl
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-
R2SnCl2
RSnC1,
-
inorganic tin (1)
of tributyltin chloride might yield products of di- and/or monobutyltin compounds and inorganic tin, and full recovery of tributyltin chloride would not occur. All methyl- and butyltin compounds subjected to the extraction conditions yielded recoveries between 96% and 104% (Table 11) indicating the absence of decomposition. The absence of decomposition products also confirmed the validity of the extraction procedure. Although the extraction conditions did not decompose the organotin compounds in the absence of oyster tissue, matrix effects could cause large variabilities in recoveries (13). The oyster tissue matrix might bind organotin compounds and interfere with their hydride formation and subsequent quantitation. Furthermore, even though no loss of alkyl groups occurred under the extraction conditions in the absence of oyster tissue, the oyster matrix might facilitate decomposition of alkyltin compounds. Thus, we determined recoveries of spikes of each methyl- and butyltin compound from the oyster matrix. Because recoveries might vary with concentration (13),two amounts of alkyltin compounds were spiked into the oyster tissue. The results demonstrated full recovery of methyl- and butyltin compounds for both low and high spikes (Table 11). In addition, the absence of products from loss of alkyl groups confirmed the lack of decomposition. Complete dissolution of oyster tissue, lack of decomposition during extraction conditions in the absence of oyster tissue, absence of decomposition in the oyster matrix, and full recovery of alkyltin compounds from oyster tissue support the validity of the extraction scheme. No published procedure for speciation of alkyltin compounds in shellfish exhibits this level of validation concomitant with minimal sample manipdation.
ANALYTICAL CHEMISTRY, VOL. 60, NO. 4, FEBRUARY 15, 1988
Comparison of Butyltin Concentrations in Oysters from Different Areas. We detected monomethyltin but no other organotin compounds in oyster samples from three sites of the Great Bay Estuary (Table 111). High tributyltin concentrations occurred in the French oyster sample measured by us (Table IV). The concentration order is tributyltin > dibutyltin > monobutyltin > TRISn. This trend suggests accumulation of tributyltin and degradation to its less toxic mono- and dibutyl forms, probably via biological processes. Shellfish samples from Japan and particularly England contained high concentrations of tributyltin. For example, Waldock and Miller (14)determined tributyltin concentrations in various samples from marinas and estuaries of the Essex coast of England. Measurable values for tributyltin had a large range with a 2900 ng of Sn/g (dry weight) maximum value. In some cases tributyltin concentration was lower than the 30 ng of Sn/g (wet weight) limit of detection. The highest tributyltin level is similar to that of our French sample (Table IV). The percent tributyltin/total tin ranged from less than 1% to 56%. Thain and Waldock ( 4 ) also determined tributyltin concentrations in oyster flesh, eggs, and larvae in samples from the Essex coast of England. Most values were ca. 110 ng of Sn/g (wet weight) in two estuaries where there was heavy boat usage and less than 36 ng of Sn/g (wet weight) in one sampling site just outside the estuary in the open sea. Tsuda et al. (15) detected 11 ng of Sn/g (wet weight) of tributyltin, but no dibutyltin, in shellfiih from a Japanese lake. Their detection limits for dibutyltin and tributyltin were about 0.5 ng/g (wet weight). The reason for high tributyltin levels in English shellfish samples and nondetection in samples from the Great Bay Estuary is undoubtedly due to the relative number of pleasure craft using antifouling paints. Sampling of oysters from England were generally in areas of high pleasure craft density, and the Great Bay Estuary is in a rural environment where boating activity is minimal. The absence of detection of monoand dibutyltin compounds in Great Bay Estuary oysters is not suprising since these compounds occur in the environment mainly as degradation products of tributyltin. In addition our samples were collected in October, when boating activity is minimal. Decomposition of tributyltin accumulated in oysters from the summer boating season might be significant.
Comparison of Monomethyltin Concentrations in Shellfish from Different Areas. Monomethyltin concentrations were much higher in Great Bay oysters (Table 111) than in limpet from the Mediterranean coast. Tugrul et al. (16)found highest mono-, di-, and trimethyltin concentrations of 5, 18, and 63 ng/g (dry weight), respectively, for limpet tissue collected inside Lamas Harbour (Mediterranean Sea, coast of Turkey). These samples contained higher concentrations of di- and trimethyltin than monomethyltin in contrast to our Great Bay Estuary samples in which only monomethyltin occurred. Oysters might have accumulated monomethyltin as a result of anthropogenic pollution, or biotic and/or chemical methylation processes. Accumulation of monomethyltin directly from its input into the estuary, however, is unlikely since poly(viny1 chloride) stabilizers contribute little to the environment (3). Gilmour et al. (17) found that a microbially mediated process in estuarine sediments causes methylation of inorganic tin to predominantly monomethyltin. Model studies by Rapsomanikis and Weber (18)proved that a carbanion-donating dimethylcobalt(II1) complex and carboca-
319
tion-donating iodomethane can separately or together methylate Sn(I1) to mono-, di-, tri-, and tetramethyltin in good yields. The biotic and chemical processes could occur outside or inside the oyster. The predominance of trimethyltin in limpet tissue (16) and of monomethyltin in the Great Bay Estuary oyster samples is interesting. This comparison suggests that monomethyltin in Great Bay oysters was a result of biological (17) or chemical (18) methylation of inorganic tin and that mono- and dimethyltin compounds in the Mediterreanean Sea samples probably result from degradation of anthropogenic trimethyltin.
Implications of Inorganic Tin and Monomethyltin in Great Bay Oysters. Inorganic tin and monomethyltin compounds detected in Crassostrea virginica oysters at the nanogram of tin per gram level from sites in the Great Bay Estuary probably do not pose any immediate threat to the oysters or their consumers. Inorganic tin and monomethyltin compounds have low toxicity. The maximum tolerance level of inorganic tin in foods established by the World Health Organization, for example, is 250000 ng of Sn/g (19). In addition, monomethyltin is relatively nontoxic among organotin compounds (3).
ACKNOWLEDGMENT We are grateful to John Nelson for collecting oysters from the Great Bay Estuary and to Pierre Michel for the French oyster sample.
LITERATURE CITED (1) Laughiln, R. B., Jr.; LindBn, 0. Amblo 1985, 14, 88-94. (2) Alzieu, C.; Sanjuan, J.; Deltrell, J. P.; Borei, M. Mar. Pollut. Bull 1988, 17, 494-498. (3) Thompson, J. A. J.; Sheffer, M. G.; Pierce, R. C.; Chau, Y. K.; Cooney, J. J.; Cullen, W. R.; Maguire, R. J. "Organotln compounds in the Aquatic Environment"; NRCCICNRC 22494, Ottawa, Canada, 1985. (4) Thain, J. E.; WaMock. M. J. Wet. Sci. Technol. 1988. 18, 193-202. ( 5 ) Valkirs. A. 0.; Davidson, B. M.; Seiigman, P. F. Chemosphere 1987, 16, 201-220. (6) Pain, S. New Sci. 1988, 28. 29-33. (7) Dwley, C. A.; Vafa, G. I n Oceans '86 Proceedings, Volume 4 , Orga notin Symposium; Marine Technology Society: Washington, DC, 1986; pp 1171-1174. (8) Davies, 1. M.; McKie, J. C.; Paul, J. D. Aquaculture 1988, 5 5 , 103-114. (9) Donard, 0. F. X.; Rapsomanlkis, S.; Weber, J. H. Anal. Chem. 1988, 5 8 , 772-777. (10) Randall, L.; Donard, 0. F. X.; Weber, J. H. Anal. Chim. Acta 1988, 184, 197-203. (11) Randall, L.; Han, J.; Weber, J. H. Environ. Technol. Lett. 1988, 7 , 571-576. (12) UNEP Sampling of Selected Marlne Organisms and Sample Prepara tion for Trace Metal Analysis ; Reference Methods for Marine Pollution Studies No. 7, Rev. 2; UNEPIFAOIIAEAIIOC: Geneva, 1984. (13) Keith, L. H.; Libby, R. A.; Crummett, W.; Taylor, J. K.; Deegan, J., Jr.; Wentler, G. Anal. Chem. 1983, 5 5 , 2210-2218. (14) Waidock, M. J.; Miller, D. "The Determination of Total and Trlbutyl Tin in Seawater and Oysters in Areas of High Pleasure Craft Activity"; International Council for the Exploration of the Sea, CM 1983/E:12, 1983. (15) Tsuda, T.; Nakanishi, H.; Morlta, T.; Takebayashi, J. J . Assoc. Off. Anal. Chem. 1988, 69. 981-984. (16) Tugrui, S.; Baikas, T. I.; Goldberg, E. D. Mar. Poilut. Bull. 1983, 14, 297-303. (17) Gllmour, C. C.; Tuttle, J. H.; Means, J. C. I n Marine and Estaurine Geochemistry Sigleo, A. C., Hattori, A., Ed.; Lewis Pub.: Chelsea, MI, 1985; pp 239-258. (18) Rapsomanlkis, S.; Weber, J. H. Environ. Sci. Technoi. 1985, 19, 352-356. (19) Weber, G. Fresenius' 2.Anal. Chem. 1985, 320, 217-224.
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RECEIVED for review May 18,1987. Accepted October 23,1987. We thank the National Science Foundation under Grant ECE-8612972 for partial support of this research.
