Assessment of QC and Uncertainty in Multiresidue Pesticides analysis in water with GC-ECD/NPD

An assessment was carried out for simultaneous determination of 25 Organochloro and Organophos pesticides residues in drinking water by gas chromatography coupled to ECD and NPD detectors. The recovery data were obtained by spiking blank samples of drinking water with pesticides at concentration levels of 30.0 μg/L, yielding recoveries in the range 90–119%. Precision values expressed as relative standard deviation (RSD) were in the range of 6.40 – 17.49%. Linearity was studied in the range 10–200 ug/L and the coefficient of correlation was higher than 0.98% for all compounds. Method Detection Limits (MDLs) and limits of quantification (LOQs) were established. The overall uncertainty of the method was estimated. The estimation of the uncertainty associated to analytical methods is necessary in order to establish the comparability of results. Multiresidue analytical methods lack very often information about uncertainty of results with likely implications when results are compared with levels established by regulations. An adequate identification and estimation of each uncertainty source allows to laboratories to establish the accuracy of results and to balance with time-consuming and costs. According to the validation data and performance characteristics as well as the high sample throughput, the proposed method is suitable for routine application.