Study On Determination Of Carbaryl Residue In Vegetables Using Flow Injection Biosensor

Carbamate pesticides are extensively used in agricultural products such as vegetables and grain etc, although they are very toxic pesticides. The pesticide residues in agricultural products become much serious due to using more and more pesticides to control the plant diseases and insect pests. So it is imperative to develop a simple and rapid detection method for pesticide residues. In current research, an enzyme inhibition method of pesticide residues has been developed.The toxic action of carbamate pesticides is based on the rapid irreversible inhibition of the cholinesterase (ChE). There is a good relationship between pesticides exposure and ChE activity. So the pesticide residues in agricultural products can be detected by analyzing the change of ChE activity. In the project, butylcholinesterase (BChE) has been immobilized and its characterization has been studied; a biosensor based on the flow injection system was constructed with the immobilized BChE and its operation conditions was been studied. On the basis of these works, a rapid method of determination carbaryl pesticide residues in the vegetables was developed.1. BChE has been immobilized with the best works condition by comparison different operation conditions and its characterization has been studied. Conditins for immobilization of BChE were with citrate buffer solution: pH7.5, alginate: 6.0%, concentration of BChE: 20%, bovine serum albumin: 0.5%, procainamide (which was used as adsorbent): 1.0%. Then drop the calcium chloride aqua which add 20 g/L, mix blend slightly, then place a 8hs under the indoor temperature, filter, wash away dirt with the lemon sour buffer aqua 2~5 times. Using glutaraldehyde(which was used as cross-linking agent): 1.2%, cross-linking time: 60min. cross-linking temperature: 35℃. Immobilized enzyme for BChE was stble in pH range and temperature range, superior than dissociated enzyme.2. Immobilized BChE esterase was used in lab FIA system. It was found that Under existing activity of immobilized enzyme, 80mmol·L-1 can be chosen as concentration of substrate.When buffer flow rate is controlled 0.6ml/ min, length of enzyme columnΦ6×40mm, a good reproducibility (RSD=1.016, n=7) of the biosensor response was obtained. The results indicated that the calibration curve of carbaryl was linear in the range of concentrations 0.2μg/ml to 146.8μg/ml. This method has been applied to the determination of real sample with satisfactory results obtained. 3. Study on determination of carbaryl residue in vegetables using a biosensor based on the flow injection system was constructed with the immobilized BChE as identification element and a spectrophotometer as transducer. The biosensor can be relived by using citrate buffer solution washing length of enzyme column 30min, or high concentration of substrate washing it 15min.