Determination of Residual Carbaryl and Pirimicarb in Environmental Water with On-line Enrichment by LC-LC Hyphenation Technique

HPLC determination of residual amounts of carbary and pirimicarb in environmental water by applying LC-LC technique for on-line enrichment,separation and detection was proposed. The YWG-C18 column (10 mm×4.6 mm,10 μm) and YWG-C18 column (150 mm×4.6 mm,10 μm) were used as the enrichment column and the analytical column respectively. A mixture of methanol and water (mixed in the ratio of 45+55) was used as the mobile phase with the flow-rate of 1 mL·min-1. Wavelength of UV-detection was taken at 228 nm. Flow-rate of sample solution in the pre-enrichment process was 5 mL·min-1. Seepage volume and amount of seepage were also studied. Linear relationship between values of the analytical signal and concentration of both pesticides was kept in the range of 0.04-1.0 μg·L-1. Detection limit (S/N=3) of carbaryl was found to be 0.008 μg·L-1 and of pirimicarb to be 0.014 μg·L-1. Values of recovery found were in the range of 93.0%-119%. Within-day and between day precision were tested,giving values of within-day RSD′s in the range of 1.3%-20.0% (for carbaryl) and of 2.0%-10.8% (for pirimicarb),and values of between-day RSD′s in the range of 2.3% to 22.2% (for carbaryl) and of 2.2%-5.8% (for pirimicarb).