Coupling stir bar sorptive extraction‐dispersive liquid–liquid microextraction for preconcentration of triazole pesticides from aqueous samples followed by GC‐FID and GC‐MS determinations

Abstract

Stir bar sorptive extraction (SBSE) combined with dispersive liquid-liquid microextraction (DLLME) has been developed as a new approach for the extraction of six triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, triticonazole and difenconazole) in aqueous samples prior to GC-flame ionization detection (GC-FID). A series of parameters that affect the performance of both steps were thoroughly investigated. Under optimized conditions, aqueous sample was stirred using a stir bar coated with octadecylsilane (ODS) and then target compounds on the sorbent (stir bar) were desorbed with methanol. The extract was mixed with 25 microL of 1,1,2,2-tetrachloroethane and the mixture was rapidly injected into sodium chloride solution 30% w/v. After centrifugation, an aliquot of the settled organic phase was analyzed by GC-FID. The methodology showed broad linear ranges for the six triazole pesticides studied, with correlation coefficients higher than 0.993, lower LODs and LOQs between 0.53-24.0 and 1.08-80.0 ng/mL, respectively, and suitable precision (RSD < 5.2%). Moreover, the developed methodology was applied for the determination of target analytes in several samples, including tap, river and well waters, wastewater (before and after purification), and grape and apple juices. Also, the presented SBSE-DLLME procedure followed by GC-MS determination was performed on purified wastewater. Penconazole, hexaconazole and diniconazole were detected in the purified wastewater that confirmed the obtained results by GC-FID determination. In short, by coupling SBSE with DLLME, advantages of two methods are combined to enhance the selectivity and sensitivity of the method. This method showed higher enrichment factors (282-1792) when compared with conventional methods of sample preparation to screen pesticides in aqueous samples.

Synthesis and application of a novel molecularly imprinted polymer‐coated stir bar for microextraction of triazole fungicides in soil

“…1, n-Hexane; 2, toluene; 3, tetrahydrofuran; 4, ethyl acetate; 5, chloroform; 6, acetone; 7, acetonitrile; 8, methanol; 9, dimethyl sulfoxide; 10, water. 0.14-0.34 mg/L, which was lower than the LODs obtained for triazole fungicide using the commercial stir bar [28].…”

“…Information about the residues in agricultural products and environment is important in assessment of the potential risk associated with the exposure. Several methods for monitoring triazole fungicides have been reported, including gas chromatography (GC) [28], highperformance liquid chromatography (HPLC) [29,30], liquid chromatography coupled with mass spectrometry (LC-MS). However, the complex sample matrices in biological and environmental samples often affect the analytical accuracy.…”

Recent Advances in Dispersive Liquid - Liquid Microextraction for Organic Compounds Analysis in Environmental Water: A Review

“…Stir bar sorptive extraction (SBSE)-DLLME was proposed by Farajzadeh et al [92] coupled with GC-FID to determine six triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, triticonazole and difenconazole) in aqueous samples. The sample solution was stirred using a stir bar coated with octadecylsilane (ODS) and then the analytes on the sorbent (stir bar) were desorbed with methanol.…”

Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid–liquid microextraction coupled with gas chromatography–mass spectrometry

“…To increase the dispersion of the extraction solvent into the aqueous solution, resulting in shorter equilibration time and enhancement the extraction efficiency, vortex agitation has been used [35]. For more complex matrices, such as honey, vegetable or soil samples, a two-step microextraction was proposed [49][50][51]. It is based on the combination of different extraction techniques, which are mostly DLLME and solid-phase extraction (SPE).…”