Comparative evaluation of solid-phase extraction and in-tube liquid-liquid extraction for determination of triazole pesticides in water samples

摘要

In this study, we have compared two extraction methods (in-tube liquid-liquid extraction and solid-phase extraction) in terms of precision, recovery percentage and time. Parameters, influencing the extraction efficiency, such as nature and volume of extraction solvent and pH nature were optimised. Under the optimum conditions, results showed that SPE is certainly more effective than in-tube liquid-liquid extraction. In this method, a volume of the sample solution is acidifed to pH 4.0 and then passed through C18 cartridge, the absorbed analytes are eluted by an appropriate solvent (acetonitrile), the cartridge was centrifuged and finally, the elute was recovered. The extract was evaporated directly with a weak nitrogen stream. The obtained extract was injected into gas chromatography-Mass spectrometry. The results of the validation indicated that this method provided an excellent linearity with correlation coefficients ranged from 0.997 to 0.999; low limits of detection and quantification in the ranges of 0.01-0.04 mu g.L-1 and 0.03-0.14 mu g.L-1 respectively. Extraction recoveries ranged from 79 to 94, Enrichment factors in the range of 158-188 and Relative Standard Deviations are less than 3. At the end, the proposed procedure was successfully applied to the analysis of real samples, the average concentrations of triazole pesticides are 0.51 mu g.L-1 and 8.79 mu g.L-1. The predominant triazoles founded are Myclobutanil (1.61-8.79 mu g.L-1) and Penconazole (0.99-6.89 mu g.L-1). Results show that all recorded triazole concentrations exceed the values standardised by the regulations.