Matrix effect of cucumber [Cucumis sativus] on fenitrothion and imidacloprid residue analysis by a commercially available ELISA kit

The matrix interference of cucumber was investigated using a commercially available ELISA kit to analyze residual fenitrothion and imidacloprid. The recovery rate was over 150% in a sample with low concentration pesticides (fenitrothion; 0.04 microg/g, imidacloprid; O.2 microg/g); therefore, the ELISA kit was not practical for screening pesticide residue at low concentrations. Cucumber fruits were divided into three organs: a fruit receptacle including an exocarp, mesocarp, and placenta including a seed. The extract of the fruit receptacle controlled the optical density value, which was notably confirmed on fenitrothion measurement. The recovery rate of the sample processed by ultrafiltration was greatly improved.