Simultaneous determination of the pesticide naptalam and its metabolites in natural water by Fourier transform infrared spectrometry

A new strategy was developed to improve the limits of detection in Fourier transform infrared (FTIR) spectrometry for the simultaneous determination o f the pesticide naptalam, N-(1-napththyl)phthalamic acid (NAP), and its met abolites, 1-naphthylamine (NNA) and N-(1-naphthyl)phthalimide (NPhDA), in n atural water. The proposed method consists of preconcentration of samples u sing conventional C-18 solid-phase extraction (SPE) discs, subsequent eluti on with methanol and dissolution of the residues in dimethyl sulfoxide afte r vaporization of the extract, absorbance measurements by FTIR in the spect ral region 1500-1800 cm(-1) and prediction of concentrations of the compone nts in recovered solutions using the partial least squares calibration mode l. The SPE recoveries for NAP, NNA and NPhDA were 98 +/- 4, 94 +/- 3 and 96 +/- 3%, respectively. The detection limits of the proposed coupled SPE-FTI R method for NAP, NNA and NPhDA in water samples were 111, 72 and 90 ppb, r espectively.