Development of a method for the simultaneous determination of six sulfonylurea herbicides in wheat, rice, and corn by liquid chromatography-tandem mass spectrometry

A Review on Recent Innovations of Pretreatment and Analysis Methods for Sulfonylurea Herbicides

Sulfonylurea herbicides (SUHs) are widely used in agriculture because of their low dosage, low cost, and high selectivity. However, due to improper use and lack of effective management, their residues pose a threat to the human health through environment and food pollution. Therefore, there is a need for simple, quick, economical, and effective methods to analyze SUHs in plant-derived foods, crops, and environmental samples. The present article presents a comprehensive review of the pretreatment and analytical technologies used for SUHs in various sample matrices, focusing on the developments since 2010. The main pretreatment methods include liquid-liquid extraction, solid-phase extraction, QuEChERS, and different microextraction methods, whereas analytical methods mainly include liquid chromatography coupled with different detectors, capillary electrophoresis, among others. In addition, the present study also compared the advantages and disadvantages of the methods and the future development is prospected.

An alternative analytical strategy based on QuEChERS and dissolvable layered double hydroxide dispersive micro-solid phase extraction for trace determination of sulfonylurea herbicides in wolfberry by LC-MS/MS

In this work, a combination of QuEChERS and dispersive micro-solid phase extraction (D-μ-SPE) based on dissolvable layered double hydroxide (LDH) has been established for preconcentration and enrichment of sulfonylurea herbicides (SUHs) in wolfberry samples. The QuEChERS was used for extraction and purification of SUHs, followed by D-μ-SPE for further enrichment of targeted analytes to obtain superior extraction performance. Dissolvable LDH nanosheets were used as absorbents, thus eliminating the elution step needed in traditional D-μ-SPE. The main influence experimental variables including pH of sample solution, amount of LDH, vortex time and volume of acidic solution were optimized in detail. Under the optimized conditions, the proposed method shows high precision (RSDs < 12.7%), low limits of detection (0.01-0.5 ng/g) and limits of quantitation (0.1-2.0 ng/g), acceptable recovery (80.1%-97.1%), thus making it a good alternative analytical strategy for the determination of SUHs residues at the low nanogram per gram range with desirable sensitivity.

Residue analysis of orthosulfamuron herbicide in fatty rice using liquid chromatography-tandem mass spectrometry

In the present study, orthosulfamuron residues were extracted from fatty (unpolished) rice and rice straw using a modified QuEChERS method and analyzed using liquid chromatography–tandem mass spectrometry. The matrix-matched calibration was linear over the concentration ranges of 0.01–2.0 mg/kg with determination coefficient (R²) ⩾ 0.997. The recovery rates at two fortification levels (0.1 and 0.5 mg/kg) were satisfactory and ranged between 88.1% and 100.6%, with relative standard deviation (RSD) <8%. The limit of quantitation, 0.03 mg/kg, was lower than the maximum residue limit, 0.05 mg/kg, set by the Ministry of Food and Drug Safety in the Republic of Korea. The developed method was applied successfully to field samples harvested at 116 days and none of the samples were positive for the residue.

Simultaneous determination of acidic pesticides in vegetables and fruits by liquid chromatography--tandem mass spectrometry

A sensitive and efficient method has been developed for the simultaneous determination of 73 multi-class acidic pesticides, such as phenoxy acid and sulfonylurea herbicides, in vegetables and fruits. The sample preparation procedure was carefully optimized for the efficient removal of co-extracted matrix components. The method involves extraction of acidic pesticides with acetonitrile containing hydrochloric acid, removal of water from crude extract by salting out, and sequential cleanup by octadecylsilyl silica gel and silica gel columns. For samples containing high amounts of pigments, such as spinach, additional cleanup using a graphitized carbon column was performed prior to liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Recovery tests were performed for five times for each sample of cabbage, spinach, potato, eggplant, orange, and apple fortified at 0.01 mg kg-1. Out of the 73 tested pesticides, 70 for cabbage, 67 for spinach, 69 for potato, 67 for eggplant, 64 for orange, and 70 for apple were within the range of 70-120%, with relative standard deviations below 25%. Nitenpyram and pyrasulfotole showed low recoveries for all the samples tested, probably due to low recoveries from silica gel column. The developed method effectively removed co-extracted matrix components and was highly selective, with no interfering peaks found in the chromatograms of blank samples. The overall results indicate that the developed method is suitable for the quantitative analysis of acidic pesticide residues in vegetables and fruits.

Determination of sulfonylureas in cereal samples with electrophoretic method using ionic liquid with dispersed carbon nanotubes as electrophoretic buffer

A capillary electrophoresis method to determine four sulfonylureas in grain samples was developed using 10mM of 1-butyl-3-methyl imidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer solution. 2mgL(-1) of Surfactant Coated-Single Wall-Carbon Nanotubes (SC-SWCNTs) was added to the buffer solution to improve the resolution. In this way, the separation of nicosulfuron, ethoxysulfuron, sulfometuron methyl and chlorsulfuron was carried out in 16min without using organic solvents. A clean up-preconcentration procedure was done prior to inject the sample into the CE instrument, in order to achieve the established maximum residue limits (MRLs). So, the detection limits (LODs) for each analytes were between 16.8 and 26.6μgkg(-1). The relative standard deviations (RSDs) were in the range 1.9-6.7%. A recovery study using the so-called matrix matched calibration demonstrates that no matrix interferences were found throughout the determination. The recovery percentages were ranged between 80% and 113%.