| A micellar electrokinetic chromatographic method (MEKC) was developed to separate and quantify maleic hydrazide (MR) in potatoes and onions. Methanol was used as the extraction solvent. A 3-ml aliquot of the extract was dried under nitrogen and the residue was reconstituted in 3-ml of water by sonication. The water fraction was passed through a tC18 solid phase extraction tube to remove interferences. The last milliliter of the water sample was collected and injected into the capillary electrophoresis (CE) system. Within-day and between-day reproducibility studies run at 2.5, 5.0, 10.0, 15.0 and 20.0 ppm indicated the procedure was reproducible. A comparison was made between CE and a high performance liquid chromatography (HPLC) method. The linear regression for maleic hydrazide was y = 0.816x + 1.071 with a correlation coefficient of 0.878.; A capillary electrophoresis method was also developed to determine maleic hydrazide in pesticide formulations. Liquid formulations were dissolved in water and injected into a capillary electrophoresis instrument and monitored at 220 mn. The running buffer was 10 mM dibasic sodium phosphate at pH 9.0. Four different liquid formulations with a guarantee of 30.2 or 30.3% potassium salt of MH were analyzed. Within-day percent coefficients of variation (%CV's) ranged from 3.0 to 7.7% and between-day %CV's ranged from 5.5 to 10.0%.; A micellar electrokinetic chromatography method was also developed to separate and quantify hexazinone and metabolites C, A1, E, B and D in groundwater. Hexazinone and its metabolites were extracted from water using Supelclean ENVI-Carb solid phase extraction tubes. Quantitation was performed using UV photodiode detection at 220, 225, 230 and 247 nm. Intra-assay and inter-assay reproducibility studies run at 0.5, 1.0, 2.0 and 5.0 ppb indicated the procedure was reproducible. A comparison of the hexazinone and metabolite B were made between CE and an established HPLC method. The linear regression for hexazinone was y = 1.007x + 0.219 with a correlation coefficient of 0.96 while the linear regression for metabolite B was y = 1.100x - 0.057 with a correlation coefficient of 0.91.; This study confirms that pesticide residue testing can be performed by capillary electrophoresis. |
