Stir octadecyl-modified borosilicate disk for the liquid phase microextraction of triazine herbicides from environmental waters

In the present article, a novel extraction/stirring approach in the liquid phase microextraction context is presented. The new technique is based on octadecyl coated borosilicate disks which act as support of the organic extracting solvent thanks to hydrophobic interactions. The disk is integrated in a stirring element which favors the transference of the analytes to the extraction phase. The proposed extraction procedure has been characterized using the determination of nine herbicides in water samples by ultra performance liquid chromatography (UPLC) combined with ultraviolet (UV) detection as model analytical problem. All the variables involved in the extraction have been studied and optimized in depth and the optimized technique provides enrichment factors in the range from 79 to 839. The method has been analytically characterized on the basis of its linearity, sensitivity and precision. Limits of detection were in the range from 0.14 μg/L (atrazine) to 0.56 μg/L (terbumeton) with precision better than 7.3% (expressed as relative standard deviation). Relative recoveries were close to 100%, which demonstrated the applicability of the stir octadecyl-modified borosilicate disk for the proposed analytical problem.