Technical Determination Of Environmental Water, The Lc-lc United Carbaryl And Pirimicarb Residues

The on-line chromatographic pre-concentration techniques have been applied for the determination of trace concentrations of carbaryl and pirimicarb.The parameters of on-line pre-concentration (breakthrough volumes and quantities, flow rate, reproducibility) and the effect of water and methanol are discussed. Breakthrough quantities of two pesticides are higher than 4.72 μg, 10.5 μg respectively. Meanwhile, it is found that the redistilled water can not be used after 3 days and methanol must have good quanlity.Detection limit of carbaryl of 0.008 μg/l and of pirimicarb of 0.014 μg/l are obtained at 228 nm.correlation coefficients of two pesticides are higer than 0.9996. In natural water, the concentration of pirimicarb of 0.070 ug/l is detected in a ditch near by Chengdu University of Technology, and the concentration of pirimicarb of 0.075 ug/l is found in a lake in Chengdu University of Technology. Recoveries of two pesticides are between 77.4% and 123%, except low concentration of carbaryl is between 39.4% and 195%. And reproducibilities and repeatabilities of two pesticides are fit the EU Council Directive EC/98/83 well (except of low concentration of carbaryl ) .The precolumn has been used for at least 170 samples including at least 30 natural samples without a significant decrease in efficiency. The parameters of column are stable after being used 3 months. It is valued to be used for more than 250 samples, if conditions of pre-concentration are optimized.The on-line chromatographic pre-concentration technique is simple, rapid, accurate and economical. It also provides a powerful tool for the analysis aqueous environmental samples. If a good choice of the preconcentration parameters and a good selection of the analytical conditions are made, the lower level determinations can be performed for the two pesticides.