Abstract:
10.00 g of the pounded and homogenized garlic sample were taken and extracted vortically with 3 mL of water, 20 mL of acetonitrile and 3 g of sodium chloride for 2 min. After centrifuging, 10.0 mL of the upper layer were taken and evaporated to near dryness at 40℃, and the residue was dissolved in 3 mL of CH
3OH-H
2O (1+5) solution, which contains
φ 1% formic acid. The solution obtained was then purified by passing through SPE column. The analytes were adsorbed on the SPE column, and were eluted from the column by CH
3OH containing
φ 0.5% of aq. ammonia. The eluates were collected and evaporated to near dryness by N
2-blowing at 40℃. The residue was dissolved with its volume made up to 1.0 mL by a mixture of acetone and
n-hexane (1+9). Contents of methyl-pyrimithate and ethyl-pyrimithate in the solution were determined separately by GC-FPD and by GC-MS. Linear relationships between values of peak areas of the 2 analytes and their mass concentrations were obtained in definite ranges, with values of lower limits of determination (10S/N) of 0.01 mg·kg
-1 for GC-FPD and GC-MS. Recovery was tested by standard addition method, giving values of recovery in the ranges from 81.6% to 91.6% and from 94.4% to 98.1% for the 2 methods respectively, and RSDs (
n=6) ranged from 4.1% to 8.6% and from 3.1% to 9.4%.