the column was treated by shaking with a small amount of Nuchar 0-190-1^, fol- 

 lowed by filtration and the washing of the filter with hexane. The method of 

 Cueto was modified by using zinc chloride in acetone and dissolving the 

 colored complex in glacial acetic acid, instead of a mixture of glacial acetic 

 acid and acetic anhydride. 



Carbaryl 



For the analysis of carbaryl, portions of the chopped sample were tumbled 

 with chloroform and the extracts were filtered through anhydrous sodium sul- 

 fate. Where the samples were analyzed by the method of Miskus, Gordon and 

 Greorge (18), a portion of the extract was concentrated to 25 ml. and chromato- 

 graphed through a dry 60-mesh Florisil column. The column was eluted with 

 chloroform. In those samples analyzed by the method of the Union Carbide and 

 Chemical Corp. ( 28) , the suggested cleanup column was modified by the addition 

 of layers of Attaclay^ and aluminum oxide. 



Heptachlor and Heptachlor Epoxide 



These residues were determined on the same portion of the plant extinct. 

 Three methods of extraction and analysis were used. In one method, the sam- 

 ples were exti^cted by tumbling with hexane, filtered through sodium sulfate, 

 and chroma tographed through a 60-mesh Florisil column. The heptachlor was 

 eluted from the column with petroleum ether followed by removal of the epoxide 

 with a 3:1 mixture of benzene; petroleum ether. The heptachlor content was 

 determined by the method of Ordas, Smith and Meyer (21) and the epoxide by the 

 method of Gannon and Decker (7) . 



In the second method of analysis, the samples were extracted by tumbling 

 with a 2:1 mixture of hexane: isopropyl alcohol. The extracts were filtered 

 and washed free of isopropyl alcohol and subjected to the same cleanup proce- 

 dures as above. In the method of Gannon and Decker (7), the Davidow reagent 

 was used instead of the specified Polen-Silverman reagent. 



In the third method of analysis, the samples were blended with a 2:1 mix- 

 ture of hexane: isopropyl alcohol and filtered, the isopropyl alcohol was 

 removed by washing, and the extracts were dried with sodium sulfate. The 

 dried extract was chroma tographed through a 60-mesh Florisil column overlaid 

 with Norit A® and the combined heptachlor and epoxide were eluted with 94:6 

 hexane :ethyl ether. The residue content was determined by the more sensitive 

 means of gas chromatography utilizing electron capture detection by the method 

 of Lovelock and Lipsky (16) . 



Toxaphene 



For the analysis of the toxaphene residues, the samples were extracted by 

 tumbling with hexane and the extract was filtered through anhydrous sodium 

 sulfate. The extract was shaken with 2 g. of Florej^, filtered, washed with 

 hexane, and concentrated, and the toxaphene residue was calculated from total 

 chlorine analysis determined by the method of Phillips and DeBenedictis (23) . 



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