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A simple and sensitive gas chromatographic ionization gas chromatography. Recoveries of 94 method is described for the analysis of residues of to 102% were obtained for artichoke and strawthe molluscicide metaldehyde ip crop tissue. berry samples fortified a t 0.1, 1.0, and 10 ppm. After extraction with benzene and cleanup on Acetaldehyde as well as other aldehydes and keFlorisil, metaldehyde was converted to acetaldetones may be determined separately by the same hyde, which was determined as its 2,4-dinitroderivatization procedure through analysis of the phenylhydrazone derivative using alkali-flame sodium bisulfite extract of the benzene solution.Since its accidental discovery as a snail and slug attractant and poison (Hadden, 1936), metaldehyde (2,4,6,8-tetramet hyl-1,3,5,7 -tetroxocane) has been widely used in spray and bait formulations for control of these pests in several vegetable and fruit crops. The molluscicide currently has a tolerance of 0 on food crops. Its use is thus restricted to applications which result in no residue in edible fruit or foliage. An efficient and sensitive method is required to support continued use and allow study of the degradation and metabolism of metaldehyde in the environment.Reported methods for quantitative analysis of metaldehyde residues are based on acid hydrolysis to form acetaldehyde which is steam distilled and determined photometrically after reaction with p-phenylphenol. Giang and Smith (1956) reported determination of fortifications as low as 1.8 ppm using this colorimetric method. The procedure was modified by Bowman et al. (1961) to allow extension to analysis of acetals, vinyl ethers, and other compounds which liberate acetaldehyde upon vigorous acid hydrolysis. Kimura and Miller (1964) included a Florisil column cleanup step to minimize interference. Even with this modification, background from control samples ranged from 0.1 to 0.7 ppm of metaldehyde equivalent in corn, bean foliage, and strawberry fruits. These high control levels, probably generated to a considerable extent during the hydrolysis step, make applications to residues less than 1 ppm subject to considerable variability.The following method provides quantitative determination of metaldehyde a t the 0.1-ppm level with little interference. It is based on conversion of metaldehyde to acetaldehyde a t room temperature, formation of the 2,4-dinitrophenylhydrazone (DNPH) and subsequent determination of the derivative by gas chromatography using the nitrogen-selective alkali-flame ionization detector. Acetaldehyde, occurring naturally in the crops and from possible decomposition of metaldehyde, is first removed from the benzene extract by washing with sodium bisulfite; it may then be determined by the same derivatization procedure if desired. EXPERIMENTAL SECTIONReagent grade tetrahydrofuran, sodium metabisulfite, 2,4-dinitrophenylhydrazine (Matheson, Coleman and Bell), acetaldehyde, Nanograde benzene (Mallinckrodt), and Florisil (PR grade, 60/100 mesh, Floridin Co., moisture content 6.7% by weig...

Methods are described for the quantitation and verification of polysorbate 60 (PS 60) in salad dressing. The sample is partitioned between methylene chloride and water. The methylene chloride extract is further treated by silica gel column chromatography. The isolated PS 60 is complexed with ammonium cobaltothiocyanate and determined spectrophotometrically at 620 nm. Additional evidence indicating the presence of PS 60 is obtained from thin layer chromatographic analysis using the modified Dragendorff reagent for visualization of spots.

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A high-pressure liquid chromatographic (HPLC) method was developed for the determination of residues of karbutilate (3-[ [(dimethylamino)carbonyl]amino]phenyl(l,l-dimethylethyl)carbamate), its hydrolysis product N'-(3-hydroxyphenyl)-N,N-dimethylurea and its demethylated metabolites monomethyl karbutilate (3-[ [ (methylamino)carbonyl)]amino]phenyl (1,l-dimethylethy1)carbamate) and demethyl karbutilate (3-[ (aminocarbonyl)amino]phenyl (1,l-dimethylethyl)carbamate), in water, soil, and grass. Recoveries of karbutilate and its degradation products from water ranged from 89 to 103%. The lower limit of sensitivity of the method is 0.01 ppm for karbutilate and N'-(3-hydroxyphenyl)-N,N-dimethylurea and 0.02 ppm for monomethyl karbutilate. The recovery of karbutilate and its carbamate metabolites from soil ranged from 84 to 95%. For residues in grass, the carbamates are converted to the corresponding phenols, which are analyzed by HPLC. The recovery of karbutilate and its carbamate metabolites from grass ranged from 80 to 87 7%. The lower limit of sensitivity of the method for residues in soil and grass is 0.1 ppm for karbutilate and 0.2 ppm for monomethyl karbutilate and demethyl karbutilate.