Application Of Gel Permeation Chromatographic Clean-up In Detecting Pesticide Residues

The fast separation and accurate determination of trace components in complex samples are arduous tasks that analysts face up to. The analysis of pesticide residues to damage to human health in foodstuff is a primary aspect of analytical chemistry. It is very important to develop simple methods for sample treatment and determination.According the kinds of pesticides used and the limits for pesticide residues in unpolished rice samples, the samples were extracted by ethyl acetate, and the rapid, accurate and sensitive methods for determining organophosphorus pesticide residues in unpolished rice were investigated by gel permeation chromatography clean-up and gas chromatography detection in this work. The details are as follows:1. The sample pretreatments were simple, effective and automatic. Ethyl acetate extracted residual organophosphorus pesticides in unpolished rice samples. The gel permeation chromatography efficiently removed macromolecule impurities such as proteins, lipids and pigments in unpolished rice extract and concentrated residual trace pesticides in unpolished rice samples with dichlormethane / cyclohexane 1:1 (v/v) as mobile phase.2. The seven kinds of common organophosphorus pesticide residues were analyzed by capillary gas chromatography with flamephotometric detector. The ranges of the detection limits were from 0.0157mg/kg to 0.0038mg/kg. The relative standard deviations were between 0.2% and 10%. The mean recoveries varied from 70% to 120 %. The Results were confirmed by gas chromatography/mass spectrometry with selected-ion monitoring. 3. The multiresidue analysis method based on gel permeation chromatography clean-up and temperature programming capillary gas chromatography with nitrogen-phosphorus detection was developed to detect 50 kinds of organophosphorus pesticide residues in unpolished rice samples. The ranges of the minimum detectable concentrations were0.089～0.001 mg/kg which depended on the compounds. The coefficients of variation ranged from 1.7% to 18.9%. The average recoveries for 40 kinds of pesticides at 3 fortification levels were 70%～120%. The determination limits of analysis methods were lower than maximum residue limits of organophosphorus pesticides allowed for unpolished rice by European Union, Japan, America, and China.4. The analysis method established in this work for organophosphorus pesticide residues in unpolished rice samples is simple, rapid, sensitive, accurate, and of high practical application value. The results obtained were satisfactory. 5. The study on organophosphorus pesticide residues in unpolished rice samples by gel permeation chromatography clean-up and temperature programming capillary gas chromatography with nitrogen-phosphorus detection has not been reported before this work.