Facile and selective recognition of sulfonylurea pesticides based on the multienzyme-like activities enhancement of nanozymes combining sensor array

Traditional identification methods based on cholinesterase inhibition are limited to recognizing organic phosphorus and carbamate esters, and their response to sulfonylurea pesticides is weak. Residual sulfonylurea pesticides can pose a threat to human health. So, it is very important to develop an effective, rapid and portable method for sulfonylurea pesticides detection. Herein, we first found that sulfonylurea pesticides have activity-enhancing effects on copper-based nanozymes, and then combined them with the array technology to construct a six-channel sensing array method for selectively identifying sulfonylurea pesticides and detecting total concentration of sulfonylurea pesticides (the limit of detection was 0.03 µg/mL). This method has good selectivity towards sulfonylurea pesticides. In addition, a smartphone-based colorimetric paper sensor analysis method was developed to achieve the on-site detection of the total concentration of sulfonylurea pesticides. And this array can also be used for individual differentiation (1-100 µg/mL). Our work not only investigates the specific responses of copper-based nanozymes to sulfonylurea pesticides, but also develops a simple method that contributes to directly detect sulfonylurea pesticides at the source of pollution, providing insights for further research on sulfonylurea pesticides detection and filling the gap in pesticide residue studies.

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

A sensitive and reliable method was developed and validated for trace determination of sulfonylurea herbicides residues in cereals (wheat, rice, and corn) by liquid chromatography-tandem mass spectrometry. The selected analytes were ethoxysulfuron, ethametsulfuron-methyl, bensulfuron-methyl, chlorimuron-ethyl, pyrazosulfuron-ethyl, and cyclosulfamuron. In this work, the extraction procedure was performed by using a mixture solvent of phosphate buffer (pH 9.5)/acetonitrile (8:2, v/v) as the extraction solvent and then was cleaned up by using Spe-ed C18/18% SPE cartridges, providing good recoveries for all of the tested analytes and with no matrix effects affecting method accuracy. The limits of detection for the studied analytes in cereal samples were between 0.043 and 0.23 μg kg(-1), and the limits of quantification were between 0.14 and 0.77 μg kg(-1), lower in all cases than the maximum residue limits permitted by the European Union for this kind of food. The developed methodology has demonstrated its suitability for the monitoring of these residues in cereal samples with high sensitivity, precision, and satisfactory recoveries.

Determination of ten sulfonyl urea herbicides in unpolished rice by solid-phase extraction cleanup and LC-diode array detection

A liquid chromatographic (LC) method with diode array detection (DAD) was developed for screening of 10 sulfonyl urea herbicide residues in unpolished rice. The investigated herbicides were azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethoxysulfuron, flazasulfuron, imazosulfuron, metsulfuron-methyl, pyrazosulfuron-ethyl and tribenuron-methyl. Acetonitrile-water (2:1) extracts of rice samples were cleaned up with solid-phase extraction cartridges (octadecylsilane-bonded silica (ODS) and graphitized carbon black (GCB)). Three fractions of the GCB eluate were taken for analysis using 3 separate injections in order to avoid interference in LC-DAD analysis and to reduce analyte coelution problems. Recoveries from rice samples fortified with the 10 herbicides at 0.05 and 0.2 microgram/g ranged from 46.6 to 119.6%, and coefficients of variation were 3.1-12.6%. The quantitation limits were 0.01-0.02 microgram/g.

Immunoaffinity purification of chlorimuron-ethyl from soil extracts prior to quantitation by enzyme-linked immunosorbent assay

A competitive-indirect enzyme-linked immunosorbent assay (CI-ELISA) was developed to quantify chlorimuron-ethyl in soil. The linear working range of the assay was from 1 to 1000 ng mL(-)(1). The assay had an I(50) value of 54 ng mL(-)(1), with a limit of detection of 2 ng mL(-)(1) and a limit of quantification of 27 ng mL(-)(1). Three soils were extracted using a carbonate buffer (pH 9.0) and the extracts spiked with chlorimuron-ethyl. Because of the effects of coextractants (matrix effects) from soil on the accuracy and precision of the ELISA, immunoaffinity chromatography (IAC) was used to purify chlorimuron-ethyl from soil extracts prior to analysis. The immunoaffinity columns, which had a total binding capacity of 1350 ng of chlorimuron-ethyl mL(-)(1) of immunosorbent, were prepared by binding anti-chlorimuron-ethyl antibodies to protein G Sepharose 4B. Although the matrix effects were largely removed using the affinity column, they could be completely removed by first passing the extract through a column containing epoxy-coupled 1,6-diaminohexane (EAH) Sepharose 4B to remove organic acids prior to IAC. Assay sensitivity was increased 100-fold using IAC to purify and simultaneously concentrate chlorimuron-ethyl from soil extracts. The purification strategy (EAH followed by IAC chromatography) removed matrix effects from all three soils and allowed for the accurate quantitation of chlorimuron-ethyl in soil extracts.

Analysis of agrochemicals by capillary electrophoresis

An increasing amount of articles using capillary electrophoresis as an investigation tool for pesticides and environmental pollutants were found over the last few years in analytical chemistry oriented journals. This review covers a wide literature range of the 1990s and concentrates on the analysis of organic agrochemicals (herbicides, fungicides, insecticides, acaricides, etc.) with capillary electrophoresis (capillary zone electrophoresis, micellar electrokinetic chromatography with CE-UV-visible or laser-induced fluorescence detection) as well as with the on-coming hyphenated techniques like capillary electrophoresis-electrospray ionization mass spectrometry. The principal preconcentration methods that allowed real sample analysis with CE are also briefly discussed. The pesticides, the separation methods, the used electrolytes, the detection types, the detection limits and the preconcentration methods were classified and presented in tabulated form as a rapid information tool.

Herbicide and plant growth regulator analysis by capillary electrophoresis

Capillary electrophoresis (CE) is a relatively new analytical technique that is just beginning to be employed in the area of pesticide residue analysis. With the development of more sensitive detectors and in conjunction with CE separation powers, it should be a well accepted technique for pesticide residue analysis in the future. This review describes CE methods that have been developed to analyze herbicides and grow regulators in water, soil and food.

Separation of fungicides by micellar electrokinetic capillary chromatography

Capillary electrophoresis with ultraviolet detection (CE/UV) of selected fungicides (carbendazim, metalaxyl, propiconazole, and vinclozolin) using different buffer compositions was investigated. Capillary zone electrophoresis (CZE) with 10 mM sodium phosphate (pH 7.0) was not useful in separating the four fungicides used in this study. However, the four fungicides were well resolved by employing micellar electrokinetic capillary chromatography (MEKC). Among the two surfactants tested in MEKC, bile salts provided better separation compared to sodium dodecyl sulfate (SDS). A buffer consisting of 10 mM sodium phosphate with 100 mM sodium cholate and 10% methanol (pH 7.0) gave best results; excellent separation of the four compounds was achieved in less than 15 min. The CE/UV method was validated by analyzing deionized and lake-water samples fortified with known concentrations for the four fungicides. Average recoveries of the fungicides in lake water of 4 micrograms/L level ranged from 42 to 87%.