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viously heated to 500° C) was mixed with the sample. The dried mixture was ground to a fine powder with a stainless steel rod and packed into a chromatographic column, 20 mm in inside diameter (i.d.), fitted with a 200-mL reservoir open on top. For the 1978-79 analyses each 10-g sample aliquot was thawed and mixed with 40 g of Na2SO4 and packed into a similar 20-mm chromatographic column fitted with a 200-mL reservoir on top, but with a removable Teflon stopcock at the bottom. The 1976 samples were extracted with 200 mL of 5 % diethyl ether in petroleum ether and the 1977-79 samples with 200 mL of dichloromethane. The solvent was allowed to percolate through the sample at 3-5 mL/min; the flow rate was adjusted by tamping the mixture with an aluminum rod (15 mm in diameter) in 1976-77, or by adjusting the stopcock opening in 1978-79. The extracts were collected in a 250-mL round-bottomed flask fitted with a 10-mL reservoir at the bottom (May and Stalling 1979) and evaporated to 5 mL by rotoevaporation. Lipid and Moisture Determination The concentrated extracts were diluted to 10 mL with gel permeation chromatography (GPC) solvent, and 1 mL was transferred to a pre-weighed 7.8-g (2-dram) vial. The solvent in this aliquot was evaporated to dryness overnight before the percent lipid was determined gravimetrically. The rest of the diluted extracts were cleaned up by GPC. Percent moisture content in separate aliquots of each homogenized whole-body composite was determined with a C. W. Brabender Moisture and Volatiles Tester. Moisture determinations were initiated at the start of the 1977 sample year. Gel Permeation Chromatography Automated GPC was used to separate organochlorines from fish oils in the extracts. In 1976 a 35-g bed of SX-3 Biobeads gel resin (Bio Rad, Richmond, California) was used with a solvent system composed of 25 % toluene in ethyl acetate in a 40-cm x 2.5-cm (i.d.) glass column with two adjustable end plungers (Glenco Scientific, Inc., Houston, Texas). The column was placed on an automated low-pressure GPC Autoprep 1001 chromatography unit (ABC Labs, Inc., Columbia, Missouri) capable of handling up to 23 samples. The sample extracts were diluted 1:1 with GPC solvent, and 5 mL (but not more than 1 g lipid) were placed on the GPC column. The first 80 mL were directed to a waste container, and the next 80 mL were collected in a 125-mL flask fitted with a calibrated 5-mL reservoir on the bottom (May and Stalling 1979). The GPC procedure was modified, starting in 1977. A 60-g bed of SX-3 Biobeads in a 60-cm x 2.5-cm (i.d.) glass column was used with a solvent system of 1:1 dichlorometh- ane in cyclohexane. The first 155 mL were discarded; the second 100 mL were collected in a 250-mL double reservoir flask (May and Stalling 1979). The GPC eluates were roto- evaporated and prepared for Florisil chromatography. Florisil Adsorption Chromatography We used Florisil adsorption chromatography to further clean up fatty extracts and to initially fractionate organo- chlorine compounds before determining rfrultiple residues by gas-liquid chromatography (GLC), Most chlorinated pesticides and PCB's were eluted from a Florisil column with a 6 % (by volume) eluent of diethyl ether in petroleum ether, followed by elution of more polar Compounds with ether mixtures ranging from 20 to 40 %. In 1976 the GPC concentrate was diluted to 5 mL with petroleum ether before it was placed on a 5-g Florisil column (80/100 mesh, Fisher Scientific). Florisil columns were prepared by placing a 1-em layerof anhydrous Na2SO4 on a pledget of glass wool in a chromatography column (30 cm x 1 cm i.d.) fitted with a 7' 5°mL reservoir open on top (Ace Glass, Vineland, New Jorsey). 'VVe'then added 5 g Florisil (activated at 130° C) to the:column and topped it with another 1-cm layer of NagSO4. Each prepared column was next washed with 20 mL.of petroleum ether. When the top of the wash solvent reached the top of the upper Na2SO4 layer, half of the GPC concentrate was transferred to the column and allowed to ;drain onto the bed of Florisil. The column walls were washed with 5 mL of the first elution solvent (40 mL of,,?T =diethyl ether in petroleum ether). When the wash solvent reached the top of the Florisil, the remaining elution s91-Yent was added, and the eluate was collected for further separation of pesticides from PCB's. The second elgfion.solvent (40 mL of 20% diethyl ether in petroleum ether.)'was then added; this eluate was collected for GLC analysis of strongly polar pesticides (e.g., dieldrin, endrin, and-daethal). Silica Gel Adsorption Chromatography We separated PCB's from most of the;pesticides with silica gel chromatographic techniques modified-ftarn Kadoum (1967). Silica gel columns were prepared :by lightly plug- ging a chromatography column (30 s x 1,crn i.d.) with glass wool, adding a 1-cm layer of Na?SO4 and 5 g of silica gel (activated at 130° C), and toppingwith an additional 1-cm layer of Na2SO4. The prepared,wlunuis were pre- washed with 20 mL hexane. When the -.bexane wash reached the top of the Na2SO41 the ,sample was added to the column and rinsed with 5 mL pf tbc=first.eluant and allowed to sink into the bed. The rest,of the first cluant was added and allowed to drip into a 12-rnl double reser- voir flask (May and Stalling 1979).'The;first eluate (PCB fraction) contained the PCB's, HC,13, ;heptachlor, aldrin, mirex, and most of the p,p'-DDE. The second duate (pesti- cide fraction) contained the rest of tbe,DDE,. the BHC iso- mers, toxaphene, DDT and its homolpgs, clllardane (in- cluding the nonachlor isomers), oxydhlordane,.heptaeblor epoxide, and methoxychlor. In 1976-77, Silicar GC-7 silica gel (Mallinckrodt, 70/230 mesh) was used. The PCB fraction was eluted with 0.5% benzene in hexane, and the pesticide fraction with 15 mL