Determination and decline study of matrine residue in tobacco by gas chromatography-nitrogen chemiluminessence detector

A simple and rapid method for determination of matrine in fresh tobacco leaves has been established.Matrine in tobacco samples was extracted by 0.01 mol/L acetic acid solution (pH=3.5) ,then cleaned up with strong cation exchange-solid phase extraction (SCX-SPE) and determined by gas chromatography-nitrogen chemiluminessence detector (GC-NCD) .Comparison of the cleanup effect between conventional solvent extraction and SCX-SPE was carried out.The results showed that SCX-SPE was more effective.Under the selected chromatographic conditions,the linearity between mass concentration and peak area was satisfied (R2=0.999 7) in the range of 0.15-15.0μg/mL.At the spiked levels of 0.05-0.4 mg/kg in blank tobacco samples,the recoveries were 89.5%-91.6% with RSD of 2.7%-3.6%,respectively.The limit of detection (LOD) of this method was 0.03 mg/kg.The results could achieve residue demand of matrine in tobacco samples.Furthermore,field experiment results indicated that the curve of decline dynamics followed the first-order kinetics equation.The half-life of matrine were 7.64 days in tobacco,which indicated that matrine should be classified as easily degradable agrochemical.