Publications (2)0 Total impact
-
Article: New method for the rapid determination of triazine herbicides and some of their main metabolites in water by using coupled-column liquid chromatography and large volume injection
[show abstract] [hide abstract]
ABSTRACT: Coupled-column liquid chromatography with ultraviolet detection was applied to the trace-level determination of simazine, atrazine, terbuthylazine and terbutryn, as well as the main atrazine metabolites, deisopropylatrazine, deethylatrazine and hydroxyatrazine, in environmental water samples rendering a very sensitive and rapid method which does not require any preconcentration step of the water sample. A sample volume of 2 ml, previously buffered with ammonium acetate for the determination of metabolites, was directly injected in the chromatographic system using two reversed-phase C18 coupled columns. Detection limits between 0.1 and 0.5 μg l−1 were directly reached for both the parent pesticides and the polar metabolites. All these compounds were successfully recovered from different environmental waters. Drinking and surface water samples were spiked at different concentration levels (1–20 μg l−1) yielding average recoveries between 86 and 104% (n = 5) with coefficients of variation between 1 and 7%. If necessary, lower detection limits, between 0.02 and 0.1 μg l−1, were easily reached by preconcentration of 100 ml of water samples using SPE cartridges. Recovery experiments were performed on drinking water samples spiked at 0.1 and 0.5 μg l−1 yielding average recoveries between 84 and 103% with coefficients of variation between 1 and 6%.Journal of Chromatography A. -
Article: Automated sample clean-up and fractionation of chlorpyrifos, chlorpyrifos-methyl and metabolites in mussels using normal-phase liquid chromatography
[show abstract] [hide abstract]
ABSTRACT: An automated method based on normal-phase LC has been developed for the sample clean-up of mussel extracts prior to gas chromatographic analysis of residues of chlorpyrifos, chlorpyrifos-methyl and their metabolites chlorpyrifos-methyl-oxon and 3,5,6-trichloro-2-pyridinol. Pesticides were extracted by means of a high speed blender using acetonitrile-acetone (90:10, v/v). The extract obtained was filtered and concentrated using rotavapor and the residue was dissolved in hexane. One ml of the hexanoic extract was injected on the silica-gel column, using hexane as mobile phase. Pesticides and metabolites were eluted in fat-free fractions with different mixtures of hexane-ethyl acetate. Diode array detection allowed monitoring on-line the elution of lipids. Purified extracts were analyzed by GC using nitrogen-phosphorus detection for quantitation and MS for confirmatory purposes. The method is fully automated from the injection of the extract to the collection of fractions, which are directly injected into the GC system. In this way, neither further clean-up nor solvent exchange were necessary prior to GC analysis. Recoveries obtained from fortified mussel samples at two concentration levels −100 and 20 ng g−1 for parent pesticides and 200 and 40 ng g−1 for metabolites — were higher than 90%. Limits of detection of the whole procedure of analysis were lower than 1 ng g−1 for parent pesticides and than 10 ng g−1 for metabolites. This method has been successfully applied to bioconcentration studies with mussels exposed to chlorpyrifos. Chlorpyrifos and its metabolic derivative 3,5,6-trichloro-2-pyridinol were detected and confirmed by MS in analyzed samples.Journal of Chromatography A.
