Determination of pyrimethanil residue in Corydalis yanhusuo, Fritillaria thunbergii and Paeonia lactiflora by gas chromatography

A method has been developed for the determination of pyrimethanil residue in Corydalis yanhusuo W. T. Wang, Fritillaria thunbergii Miq. and Paeonia lactiflora Pall. by using gas chromatography. Samples were extracted with dichloromethane, cleaned up by column chromatography (neutral alumina-florisil=3:2, m/m) followed by liquid-liquid partition. Then pesticide residue was determined by gas chromatography with nitrogen-phosphorus detection (NPD), and the matrix-matched external standard method was applied for the quantitative analysis. The confirmation of pyrimethanil was performed by GC-MS/MS. Good linearity was obtained at concentrations of 0.02-10 mg/L with R2 higher than 0.999 in n-hexane and blank matrix solution. The spiked recoveries varied from 75% to 104% at 0.01 (0.02 in C. yanhusuo), 0.1, and 0.5 mg/kg spiked levels, respectively. The intra-day relative standard deviation ranged from 1.3% to 10.2% (n=5) and the inter-day relative standard deviation ranged from 1.2% to 9.0% (n=3), in various matrixes. The limit of quantification (LOQ) in C. yanhusuo, F. thunbergii and P. lactiflora was 0.02, 0.01, and 0.01 mg/kg, respectively. This analytical method met with the requirement of pesticide residue analysis. It was simple, reliable, and with better purification effect, which could be applied to the determination pyrimethanil residue in these three kinds of Chinese medicinal herbs.