High-pressure liquid chromatographic analysis of urea herbicides in foods.
A method is described for the direct analysis of the urea herbicides linuron, monuron, diuron, chlorbromuron, fluometuron, chloroxuron, and fenuron in cabbage, corn, potatoes, turnip, and wheat at 0.01-1.0 ppm. The samples are extracted with acetone; the filtrate is partitioned with hexane-methylene chloride (1+1) followed by 2 other extractions with methylene chloride. The organic phases are dried and concentrated for column chromatographic cleanup on 2% deactivated Florisil. The column fractions are evaporated just to dryness and redissolved in 10 ml isooctane for high-pressure liquid chromatography on a 25 cm silica gel (5 mum) column. Isopropanol in isooctane is the mobile phase, and compounds are measured by ultraviolet absorption at 254 nm. Recoveries are greater than 80% in most cases. These results are confirmed by alkylation with sodium hydride-methyl iodide in dimethyl sulfoxide to form the methyl products which are analyzed by the same chromatographic system or by gas-liquid chromatography.
D002851:Chromatography, High Pressure Liquid; D005504:Food Analysis; D006540:Herbicides / Q000032:analysis*; D008722:Methods; D010573:Pesticide Residues / Q000032:analysis; D014908:Triticum / Q000032:analysis; D014675:Vegetables / Q000032:analysis
D006540:Herbicides; D010573:Pesticide Residues