Determination of N-(4-Chlorophenyl)-N´-(2,6-difluorobenzoyl)-urea in Milk by High-Speed Liquid Chromatography

Abstract

A rapid and sensitive method of analysis in which high-speed liquid chromatography was used with ultraviolet absorption detection was developed for determining residues of Thompson- Hayward TH 6040 (N-(4-chlorophenyl)-N'- (2,6-dinuorobenzoyl)urea) in cows' milk. The larvicide is extracted from whole milk with ethyl acetate, and the lipids are removed by partitioning between hexane and acetonitrile. After evaporation of the acetonitrile, the residue is dissolved in ethanol, and aliquots are injected into a liquid chromatograph, using methanol-water (1+1) as the mobile phase in a packed column. Recovery of TH 6040 from cows' milk is essentially quantitative, and no interfering substances appear on the chromatogram. The lowest detectable level was 10 ng. Milk from a cow fed 1 mg larvicide/kg body weight daily in the diet was analyzed by this procedure, and no detectable residues (<0.1 ppm) were found over a 15 week sampling interval.

Comparison of coating and immunizing antigen structure on the sensitivity and specificity of immunoassays for benzoylphenyl urea insecticides

“…Alternatively, whole milk was fortified by adding diflubenzuron in acetonitrile to give concentrations in milk ranging from 1 ppb to 10 ppt chosen so that at least three concentrations would fall on the standard curve of each ELISA. The milk samples were worked up by a modification of the method of Corley et al (1974). Whole milk (100 g) was mixed with Na2S04 (250 g) in a beaker, and then ethyl acetate (200 mL) was added.…”

Electron-capture gas chromatographic determination of diflubenzuron and permethrin in soil and water

“…The insect growth regulator diflubenzuron [Dimilin,amino]carbonyl]-2,6-difluorobenzamide] cannot be analyzed directly by electron-capture gas chromatography (ECGC) because the compound either decomposes or irreversibly adsorbs on GC columns commonly used for pesticide analyses (Corley et al, 1974). As a result, high-performance liquid chromatography (HPLC) methods were developed and successfully used to determine residues of diflubenzuron in water (Schaefer and Dupras, 1976), soil and plants (Schaefer and Dupras, 1977;Mansager et al, 1979), manure (Oehler and Holman, 1975), and fish (DiPrima et al, 1978; Schaefer et al, 1979).…”

Development of enzyme-linked immunosorbent assays for residue analysis of diflubenzuron and BAY SIR 8514

“…The classical methods of diflubenzuron analysis include GLC or HPLC. Since extensive cleanup procedures are needed, these methods are very expensive and tedious (Corley et al, 1974;DeMilo et al, 1978;DiPrima et al, 1978; Lawrence and Sundaram, 1976;Maini and Deseo, 1976; Oehler and Holman, 1975;Schaefer and Dupras, 1977; Worobey andWebster, 1977, 1978;Rabenort et al, 1978;Monem and Mumma, 1981) (Table III). For these reasons, simple and sensitive assay techniques are needed in order to analyze large numbers of samples.…”