Extraction, cleanup, and chromatographic determination of imidacloprid residues in wheat.

This study presents an improved method for quantitative analysis of imidacloprid residues in wheat grain using high performance liquid chromatography. The study used chromatographic response (in terms of peak height) as a quantitative tool for determination instead of peak area. The peak height of imidacloprid showed a very good linear correlation (R(2) = 0.999) when compared with absolute values at six different concentrations. The limit of detection was found to be 0.01 μg/mL. The recovery of imidacloprid residues in spiked wheat grain at three levels (0.03, 0.05, and 0.1 μg/g) was in the range of 79%-88% with %RSD 5.72 at 0.05 μg/g (w/w) and between 87% and 93% with %RSD 3.55 at 0.1 μg/g (w/w). At 0.03 μg/g (w/w) level, recovery was not within the recommended range of 70%-110%. Therefore, the lowest limit of quantification for this method was found to be 0.05 μg/g.