Simultaneous determination of trace levels of multiclass fungicides in natural waters by solid - phase microextraction - gas chromatography-tandem mass spectrometry.

A solvent-free method based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous determination of eleven fungicides at trace levels in different types of waters. Several experimental SPME parameters such as temperature, fibre coating, and SPME mode, were optimized in order to obtain the highest extraction efficiency. Under the optimal conditions, 100 °C, polyacrilate fibre (PA) and direct-immersion mode, the method was validated showing good linearity, repeatability and reproducibility. Recovery studies were carried out in four different real water matrices and at three concentration levels (20, 200 and 2000 ng L-1), with overall recovery values between 92 and 104% and relative standard deviations (RSD) about 10%. Limits of detection (LODs) at the low ng L-1 were obtained. The method demonstrated its suitability for the determination of fungicides in real water samples using external calibration for quantification purposes as well as for photodegradation studies at low concentration levels.