Sulfonylurea Herbicides In Soil Samples Research Articles

Switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the determination of four types of sulfonylurea herbicides in soils.

In this study, switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography was developed for the determination of four sulfonylurea herbicides in soils. For the first time, the sample pretreatment was achieved due to the similar acid-base status of sulfonylurea herbicides and switchable hydrophilic solvent. In the extraction step, sulfonylurea herbicides were extracted as anions and transferred to an alkaline solution with switchable hydrophilic solvent anions. In the concentration step, two types of anions were transformed to their molecular state after the aqueous solution was acidified. In addition, the dispersion and microextraction processes were completed efficiently with the simultaneous formation of analytes and extractants. The factors affecting the extraction performance were optimized. Under the optimized conditions, good linearity was observed for each herbicide with correlation coefficients ranging from 0.9952 to 0.9978. The limits of detection were in the range of 0.1-0.2 μg/g. Moreover, the relative recoveries of the sulfonylurea herbicides at spiking levels of 0.5, 1, and 1.5 μg/g in soil samples were between 75 and 111% (relative standard deviations: 0.4-11.4%). Therefore, the proposed method in this study could be successfully applied to the analysis of four types of sulfonylurea herbicides in soil samples.

Determination of sulfonylurea herbicides in soil samples via supercritical fluid extraction followed by nanostructured supramolecular solvent microextraction

The present work describes a sensitive procedure for extraction and determination of three sulfonylurea herbicides (metsulfuron-methyl, bensulfuron-methyl and chlorsulfuron) in water samples using supramolecular solvent microextraction. A supramolecular solvent with a nano structure made up of decanoic acid assemblies dispersed in tetrahydrofuran and water was proposed. Also, a supercritical fluid extraction coupled with supramolecular solvent microextraction was applied for extraction and determination of ultra-trace amounts of sulfonylurea herbicides in soil samples. A Taguchi orthogonal array experimental design with an OA16 (45) matrix was employed to optimize the supercritical fluid extraction conditions. In supercritical fluid extraction–supramolecular solvent microextraction procedure, a mixture of decanoic acid and the SFE collecting solvent (tetrahydrofuran) was added to water for supramolecular solvent formation. The effective parameters on the supramolecular solvent microextraction efficiency were studied and optimized using two different optimization methods: one variable at a time and face centered design. Under the optimum conditions, linear dynamic ranges varied within 0.1–5mgkg−1 (0.9978≤R2≤0.9987) and 0.5–100μgL−1 (0.9973≤R2≤0.9995) for all of the sulfonylurea herbicides in the supercritical fluid extraction–supramolecular solvent microextraction and supramolecular solvent microextraction, respectively. The intraday (n=5) and interday standard deviations were calculated by extracting the SUHs from water and soil samples through supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction. Interday RSDs% lower than 7.1% and intraday RSDs% lower than 3.8% were obtained. Limits of detection, based on a S/N ratio of 3, were 0.5μgL−1 and 0.7mgkg−1 for supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction, respectively.

Dispersive solid-phase extraction followed by dispersive liquid–liquid microextraction for the determination of some sulfonylurea herbicides in soil by high-performance liquid chromatography

Dispersive solid-phase extraction (DSPE) combined with dispersive liquid–liquid microextraction (DLLME) has been developed as a new approach for the extraction of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, bensulfuron-methyl and chlorimuron-ethyl) in soil prior to high-performance liquid chromatography with diode array detection (HPLC-DAD). In the DSPE-DLLME, sulfonylurea herbicides were first extracted from soil sample into acetone–0.15 mol L −1 NaHCO 3 (2:8, v/v). The clean-up of the extract by DSPE was carried out by directly adding C 18 sorbent into the extract solution, followed by shaking and filtration. After the pH of the filtrate was adjusted to 2.0 with 2 mol L −1 HCl, 60.0 μL chlorobenzene (as extraction solvent) was added into 5.0 mL of it for DLLME procedure (the acetone contained in the solution also acted as dispersive solvent). Under the optimum conditions, the enrichment factors for the compounds were in the range between 102 and 216. The linearity of the method was in the range from 5.0 to 200 ng g −1 with the correlation coefficients ( r) ranging from 0.9967 to 0.9987. The method detection limits were 0.5–1.2 ng g −1. The relative standard deviations varied from 5.2% to 7.2% ( n = 5). The relative recoveries of the four sulfonylurea herbicides from soil samples at spiking levels of 6.0, 20.0 and 60.0 ng g −1 were in the range between 76.3% and 92.5%. The proposed method has been successfully applied to the analysis of the four target sulfonylurea herbicides in soil samples, and a satisfactory result was obtained.

Determination and Quantitation of Ten Sulfonylurea Herbicides in Soil Samples Using Liquid Chromatography with Electrospray Ionization Mass Spectrometric Detection

A multiresidue method was developed for confirmation and quantitation of ten sulfonylurea herbicides including nicosulfuron, thifensulfuron-methyl, metsulfuron-methyl, sulfometuron-methyl, chlorsulfuron, ethametsulfuron-methyl, tribenuron, bensulfuron-methyl, pyrazosulfuron-ethyl, and chlorimuron-ethyl in soil. Analytes were extracted from the soil sample with methanol-phosphate buffer (2:8, v/v) (pH 7.8) in an ultrasonic bath. The extracts were adjusted to pH 2.5 with 85% H 3PO 4 and passed, under vacuum, through a solid-phase extraction cartridge. Several types of adsorbents were evaluated, including silica-based Cleanert C 18 and two polymeric adsorbents (Oasis HLB and Cleanert HXN). Cleanert C 18 showed good cleanup effects in the study. Determination and quantitation were performed by high performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) instrumentation equipped with an ion trap mass filter. Analytes were eluted on a HPLC column of 4.6 mm × 250 mm XDB C 18, 5 × particle size, in the mobile phase of the acetonitrile (solvent A)-methanol (solvent B)-0.2% acetic acid (solvent C). The elution gradient was as follows: the mobile phase started with 10% of acetonitrile and 10% methanol, which increased linearly to 45% in 14 min, to 48% in the next 2 min and then returned to the initial condition in 2 min. The column temperature was kept at 30°C with a flow rate of 1.0 ml/min. Thus the retention time of nine herbicides was in the range of 10 to 16 minutes. Spiked soil at 0.01–1.0 mg/kg levels was checked. Average recoveries were in the range of 80.2%–104.5% with relative standard deviations (RSDs) of 0.02%–14.90%. The limit of detection (LOD) of this method was in the range of 0.6 to 3.5 μg/kg.

Determination of sulfonylurea herbicides in soil extracts by solid-phase extraction and capillary zone electrophoresis

Sulfonylurea herbicides in soil extracts were concentrated using off-line solid-phase extraction (SPE), and determined by capillary zone electrophoresis (CZE) and UV detection. The method involves extraction of soils with 0.1 M NaHCO3 solution and subsequent preconcentration by using C18 cartridges prior to separation of the pesticide using CZE. The results show that a C18 cartridge is suitable for the purification of sulfonylurea herbicides in soil extracts with the recoveries ranging from 65–103%. The separation conditions affecting the resolution and detection sensitivity was systematically investigated. The sulfonylureas were resolved well using 30 mM sodium acetate (NaAc)/acetic acid (HAc)+10% acetonitrile (ACN) buffer at pH 4.80. The calibration plots for the test solutes in the concentration of 0.2–50 mg L−1 were linear with detection limits in the range of 0.05–0.10 mgL−1. The proposed method has been successfully demonstrated for the determination of sulfonylurea herbicides in soil samples.

Supercritical Fluid Extraction of Sulfonylurea Herbicides in Soil Samples

Abstract The application of supercritical fluid extraction (SFE) with supercritical CO2 to the analysis of 2 sulfonylurea herbicides in 4 soils is presented. Methanol and water are added to the soil samples as modifiers. After extraction, Chlorsulfuron and Metsulfuron methyl are measured by HPLC-UV at 220 nm. The recovery rates are good (>80%) for all types of the studied soils except for those with high organic carbon content (ca. 50%). According to the characteristics of the soils, recovery with SFE is similar or better than with liquid-solid extraction.