LC-MS/MS Determination of Residual Amount of Propamocarb in Cucumber

Sample of cucumber was extracted with acetonitrile, and the extract was purified by passing through the activated carbon SPE column and eluting with acetonitrile. The eluate was evaporated rotationally to near dryness, and made up its volume to 1.0 mL with acetonitrile-H2O (1+1) solution. Hypersil GOLD C18 (2.0 mm×150 mm, 3 μm) chromatographic column was used for separation, using the mixed solutions of 10 mmol·L-1 ammonium acetate (containing φ 0.1% formic acid) and acetonitrile in different ratios as mobile phase in the gradient elution. ESI with positive ionization mode and select ion monitoring mode was used in the MS/MS analysis. Linear relationship between values of peak area and mass concentration of propamocarb was found in the range of 1.02-1 020 μg·L-1, with lower limit of determination (10S/N) of 0.2 μg·kg-1. Test for recovery was made by standard addition method, giving values of recovery and RSD′s (n=6) in the ranges of 88%-96%and 4.7 %-6.4% respectively.