Determination Of Deadly Poisonous Organophosphorus Pesticides By Capillary Electrophoresis And Study Of On-line Concentration For Its Residue

A method of micellar electrokinetic capillary chromatography (MECC) with usual injection was developed for the determination of Methyl parathion. The effects of the concentration of NaHCOa and sodium dodecyl sulfate and the pH of running buffer on the efficiency of column were discussed. So the optimum conditions were as follows: NaHCOs concentration of 15mmol/L, sodium dodecyl sulfate concentration of 40mmol/L and pH10.3 in running buffer. The method has been applied to the determinations of Methyl parathion concentrates in its emulsifiable solution purchased from the market. The relative standard deviation of 5-run-determinations to methyl parathion were 0.34%~0.79%, and the recovery of them were 101.88%~ 104.76%, respectively.Sweeping is an on-line sample concentration technique in MECC, which can concentrate neutral substances. Sweeping can improve detection limit of capillary electrophoresis. A new method to determine residual methyl parathion in fresh vegetable by capillary electrophoresis was reported based on sweeping principle. The effects of the concentration of micellar, electrolyte and organic additive in running buffer, pH, the concentration of solution to dilute sample, voltage, injection pressure and the length of capillary on enhancement factor were studied.So the optimum conditions were as follows: A 50-um-i.d.capillary with a50-cm total length and 45.5-cm effective length was used to determine sample diluted by 0,5mmol/L NaH2PO4. The concentration of SDS, NaH2PO4 and methanol in running buffer was 180mmol/L, 20mmol/L, 10%(V: V), respectively. The pH of buffer was 6.2, and the run-voltage was 7kV. Pressure injection model was used and injection pressure was 2062.5 kPaxs. Under the experimental conditions above mentioned, enhancement factor of 100.38 was acquired and detection limit was 0.0814mg/kg for methyl parathion. In order to remove impurities such as pigment from sample, activated carbon was added to the solution of vegetable sample that was extracted and cleaned-up by the method of GB/T 5009.20-1996. The obvious effect of the addition of activated carbon on the recovery of methyl parathion was not found. So it was determined as the further clean-up method that activated carbon was added to the vegetable sample solution. The method has been applied to the determinations of residual methyl parathion in cabbage, rape, leek, cucumber and tomato that werebought in the market. The recovery of them were 92.42%~ 92.53%.A new method to determine residual Parathion in fresh vegetable by capillary electrophoresis was reported based on sweeping principle. The effects of the concentration of micellar, electrolyte and organic additive in running buffer, pH, the concentration of solution to dilute sample, voltage, injection pressure and the length of capillary on enhancement factor were studied. So the optimum conditions were as follows: A 50-um-i.d.capillary with a 50-cm total length and 45.5-cm effective length was used to determine sample diluted by 0.3 mmol/L NaH2PO4. The concentration of SDS, NaH2PO4 and methanol in running buffer was 120mmol/L, 20mmol/L, 30%(V: V), respectively. The pH of buffer was 6.2, and the run-voltage was 7kV. Pressure injection model was used and injection pressure was 2406.25 kPa xs. Under the experimental conditions above mentioned, enhancement factor of 107.58 was acquired and detection limit was 0.1150 mg/kg for Parathion, In order to remove impurities such as pigment from sample, activated carbon was added to the solution of vegetable sample that was extracted and cleaned-up by the method of GB/T 5009.20-1996. The obvious effect of the addition of activated carbon on the recovery of Parathion was not found. So it was determined as the further clean-up method that activated carbon was added to the vegetable sample solution. The method has been applied to the determinations of residual Parathion in cabbage, rape, leek, cucumber, tomato that were bought in the market. The recovery of them were 90.7%~90.82%.