A method is presented for the chromatographic separation and subsequent colorimetric measurement of chlorocholine chloride (CCC) at residue levels in wheat grain and plants at various stages of growth. Chlorocholine chloride is removed from tissue background by adsorption chromatography on aluminum oxide, and measured colorimetrically as a dipicrylamine-chlorocholine chloride complex at 415 mg. The average recoveries of CCC from wheat grain, green wheat foliage, and corresponding wheat straw were 76, 86.4, and 90%, respectively, with average control values of 0.10, 0.16, and 0.27 p.p.m. A rate-of-disappearance study at a treatment level of 4 pounds of CCC per acre of wheat showed a biological half life for CCC of 13 days. Gycocel[chlorocholine chloride (CCC), 2-chloroethyl trimethylammonium chloride] is a plant growth regulant. The physiological and economic importance Dipicrylamine Reagent (2,2 ',4,4',6, (Eastman Chemical Co.). Prepare a 0.01 % solution in purified methylene chloride.Aluminum Oxide. Fisher Scientific Co., Catalog No. A-540, adsorption alumina for chromatographic analysis.Amberlite LA-2 Liquid Anion Exchange Resin (Rohm and Haas Co., Philadelphia, Pa.). Prepare a 10% solution in carbon tetrachloride.Cycocel (2-Chloroethyl Trimethyl ammonium Chloride) Standard (American Cyanamid Co., Princeton, N. J.). Prepare standard solutions in methanol containing 10 and 1.0 µg. of CCC per ml. of solution.

Residues of both dimethoate and dimethoxon are extracted from finely chopped plant or animal tissues with methylene chloride. The resulting extract is concentrated and cleaned up by silica gel chromatography, if necessary. The concentrate is injected into a gas chromatograph equipped with either a flame photometric or an alkali flame ionization detector and a column containing 11% DC-200 on 60–80 mesh Gas-Chrom Q/0.01% Versamid 900. Recovery values for dimethoate and dimethoxon added a t 0.002–1.0 p pm ranged from 56 to 112% with an overall average of 89.2% for dimethoate and from 60 to 127% with an overall average of 81.9% for dimethoxon. The lower limit at which recovery values were obtained for both compounds was 0.05 p pm for plant tissues, 0.02 for animal tissues and eggs, and 0.002 for milk. Residue values obtained for animal tissues involving both exposure and feeding studies a n d for field-treated plant samples are also presented.

A colorimetric method for residues of Abate insecticide, OjOjO'jO'-tetramethyl-OjO'thiodi-p-phenylene phosphorothioate, is based on its hydrolysis to 4,4/-thiodiphenol and subsequent determination at 485 m^after reaction with 4-aminoantipyrine and periodate. Procedures are described for natural waters, mud, oysters, rice grain, and rice foliage. Recoveries and apparent Abate insecticide concentrations in control tissues are given.

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loss on standing 1 hour. At the absorbance maximum, 530 µ, interference from milk pigments is much less than at 430 µ. A further advantage is that the specific absorbance of the blue color at 530 µ is somewhat greater than the corresponding nitrofuran absorbance at 430 µ.The absorbance curves for each of these, as recorded with a Beckman DK spectrophotometer, are shown in Figure 1.This method has been applied to the milk from cows treated with a commer-FEED ADDITIVE RESIDUES cial nitrofurazone preparation according to label directions. The results will be reported in a separate publication. Literature Cited(1) Assoc. Offic. Agr. Chemists, Washington, D. C., "Methods of Analysis,"