title: Resorcinol-formaldehyde xerogel as a micro-solid-phase extraction sorbent for the determination of herbicides in aquatic environmental samples.
abstract: In this study, organic aerogels were synthesized by the sol-gel polycondensation of mixed cresol with formaldehyde in a slightly basic aqueous solution. Carbon aerogels and xerogels are generated by pyrolysis of organic aerogels. The novel sol-gel-based micro-solid-phase extraction sorbent, resorcinol-formaldehyde xerogel, was employed for preconcentration of some selected herbicides. Three herbicides of the aryloxyphenoxypropionate group, clodinafop-propargyl, haloxyfop-etotyl, and fenoxaprop-P-ethyl, were extracted from aqueous samples by micro-solid-phase extraction and subsequently determined by gas chromatography with mass spectrometry. The effect of different parameters influencing the extraction efficiency of these herbicides including sample flow rate, sample volume, and extraction time were investigated and optimized. Under optimum conditions, linear calibration curves in the range of 0.10-500 ng/L with R(2) > 0.99 were obtained. The relative standard deviation at 50 μg/L concentration level was lower than 10% (n = 5) and detection limits were between 0.05 and 0.20 μg/L. The proposed method was successfully applied to the sampling and extraction of herbicides from Zayanderood and paddy water samples.
authors.affiliation: Department of Physico Chemistry, Razi Vaccine & Serum Research Institute, Karaj, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Es-haghi
authors.affiliation: Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Zare
authors.affiliation: Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Tehran, Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Piri-Moghadam
authors.affiliation: Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Tehran, Iran.
authors.forename: Habib
authors.initials: H
authors.lastname: Bagheri
keywords: Gas chromatography with mass spectrometry; Herbicides; Micro-solid-phase extraction; Sol-gel technology; Xerogels