Determination of imidacloprid in water and soil samples by gas chromatography-mass spectrometry

A method for determination of imidacloprid in water and soil samples, previous hydrolysis in basic medium, followed by gas chromatography-mass spectrometry and selected ion monitoring. A 250-ml sample water was previously heated in basic medium to give a hydrolysis compound of adequate volatility. The hydrolysis product which was extracted and isolated with chlorotorm was identified and found to be suitable for gas chromatography analysis. Further, a clean-up is not necessary using the selected ion monitoring mode. [2H,~]Anthracene was used as an internal standard. The applicable concentration range was 5-20/xg 1 -~. Detection limit was 0.16/zg I ~ for water and 1 /zg kg ~ for soil samples. Their relative standard deviations established for different concentration levels were between 0.3 and 1%. It was applied to the check whether there was imidacloprid above these limits on waters and soil from Granada (Spain). The method was validated applying the standard addition methodology. Recovery levels of the method reached 100% in all cases.