FTIR approaches for diuron determination in commercial pesticide formulations

Two strategies have been developed for Diuron determination by FTIR spectrometry, an off-line extraction and stopped-flow determination and a fully mechanized procedure, based on the on-line extraction of Diuron and FIA-FTIR measurement of the extracts. The aforementioned procedures have been compared with a reference chromatographic method. The off-line FTIR spectra were obtained at a nominal resolution of 4 cm(-1) from 4000 to 900 cm(-1) by accumulating 25 scans. Diuron was determined using peak height measurements at 1582 cm(-1) corrected using a baseline defined between 1562 and 1614 cm(-1). The waste generation of the off-line procedure was 3.4 mL chloroform for each sample, and the method provided a LOD of 40 mu g g(-1), corresponding to 0.8% (w/w) Diuron in the original sample. The fully mechanized FIA method provided a LOD of 35 mu g g(-1), which corresponds to 0.7% (w/w) in the solid sample and a maximum sampling frequency of the whole procedure of 30 h(-1), with a waste generation of 9.3 mL per sample, taking into account the volume of CHCl3 required for sample dissolution and that need as a carrier. All those methods consume less organic solvent than a HPLC method, which involves the use of 39 mL of acetonitrile per sample and a sampling frequency of 12 h(-1).