Improved Chromatography and MS-Based Detection of Glyphosate and Aminomethylphosphonic Acid Using iTrEnDi

A novel Cu2+-coordinated fluorescent sensing system for specific detection of glyphosate and its applications in environmental and biological systems

Glyphosate is a non-selective herbicide widely used in agriculture, and its overexposure poses significant health and environmental risks. Herein, a novel Cu2+-coordinated fluorescent sensing system (HYBC-Cu2+ system) based on acylhydrazone groups was designed, capable of glyphosate-specific recognition. The HYBC-Cu2+ system was constructed with simple steps, with the advantages of short recognition time (< 1 min), good specificity, anti-interference, and excellent sensitivity (LOD = 95 nM). The effect of proton functional group on glyphosate resulted in Cu2+ of the HYBC-Cu2+ system being able to be competed down by the glyphosate to release HYBC thus inducing the fluorescence enhancement of the system and realizing the rapid detection of glyphosate. The recognition mechanism by the HYBC-Cu2+ system was verified by high-resolution mass spectrometry (HRMS), density function theory (DFT) calculations and Job's Plot. The system can cycle alternately to detect the glyphosate more than 6 times and effectively quantify trace glyphosate in environmental samples. Furthermore, the HYBC-Cu2+ system has low cytotoxicity and good membrane permeability, which can enter HeLa cells and zebrafish to react rapidly with exogenous glyphosate, resulting in fluorescence enhancements that are visually distinctive. The application of HYBC-Cu2+ system can further promote the development of pesticide residue monitoring methods such as glyphosate and provide scientific basis for policy making and public health protection.

Dual-Mode Detection of Glyphosate Based on DNAzyme-Mediated Click Chemistry and DNAzyme-Regulated CeO2 Peroxidase-like Activity

In this article, a dual-signal sensor for the fluorescence and colorimetric detection of glyphosate (Gly) is developed based on DNAzyme-mediated click chemistry and DNAzyme-regulated CeO2 peroxidase-like activity. DNAzyme can bind to Cu+, triggering a click chemistry reaction between 3-Azido-7-hydroxycoumarin (AHC) and 3-ethyn-1-ol (BOL), thus generating a strong fluorescence signal at 475 nm. Due to the strong coordination between Gly and Cu2+, the amount of reduced Cu+ decreases, resulting in a weakening of the fluorescence. In addition, Gly can inhibit the catalytic site of CeO2 enzyme activity, while DNAzyme, which does not participate in the click chemistry reaction, can be adsorbed by CeO2, further inhibiting the enzyme activity and reducing the oxidation color change of 3,3',5,5'-tetramethylbenzidine (TMB). The fluorescence detection limit of this dual-mode sensing platform is 0.15 μg/mL, and the colorimetric detection limit is 0.19 μg/mL. This method has been successfully applied to the detection of Gly in tap water and soybeans, which has a promising application in pesticide residue detection.

Improved LC-MS Detection of Opioids, Amphetamines, and Psychedelics Using TrEnDi

Substances of misuse are becoming increasingly difficult to analyze as unique methods of smuggling are adopted and due to the rapid emergence of new psychoactive substances, increasing the pool of compounds to characterize and identify. Technologies such as gas chromatography and liquid chromatography coupled to mass spectrometry (MS) represent the gold standard for accurate and robust analysis, with on-site ambient- and portable-MS systems providing rapid methods of drug screening and testing. For many samples containing residual analyte quantities, methods to improve sensitivity through chemical derivatization are critical for accurate determination. Herein, we demonstrate for the first time the use of trimethylation enhancement using diazomethane (TrEnDi) to improve the MS-based sensitivity of 13 different drugs of misuse. All analytes were successfully permethylated, with 11 demonstrating improved analytical characteristics from TrEnDi with MS sensitivity enhancements ranging from 1.2-fold to as high as 24.2-fold in the case of psilocybin, as well as increases in reversed-phase chromatographic retention for most species. Derivatization using 13C-isotopically labeled TrEnDi reagents were used to successfully resolve isobaric interference issues between three pairs of controlled substances. By using an unconventional aprotic solvent system for electrospray ionization, the benefit of a fixed-permanent positive charge was highlighted as TrEnDi-modified amphetamine was easily measured while unmodified was not detected. Finally, TrEnDi was employed to boost the sensitivity of morphine in a real urine matrix. Our results demonstrate a percent recovery of 103.1% and a sensitivity enhancement of 2.4-fold, demonstrating the versatility and applicability of TrEnDi to pre-existing analytical workflows for trace analysis.

Unveiling Readily Ionized and Robust Anionic Species: A Gateway to Enhanced Ionization Efficiency in ESI-MS Analysis

Electrospray ionization mass spectrometry has long been a prevalent ionization method in the analysis of low volatility molecules with biological, environmental, and industrial relevance. To address analytical challenges associated with molecules suffering from low ionization efficiencies (IEs), chemical derivatization (CD) strategies have been developed and are frequently adopted into workflows. However, only a minute number of CD techniques have been developed for negative polarity. To address this disparity, we evaluated 27 anions based on three criteria: (1) IE relative to a sodium dodecyl sulfate (11 + Na+) internal standard; (2) stability to collision induced dissociation; (3) diagnostic tandem mass spectrometry behavior. Highly fluorous ions exhibiting weakly coordinating and hydrophobic properties displayed enhanced IE. Trifluoromethanesulfonyl-containing ions proved to be unexpectedly labile, while tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were determined to be of optimal IE of 332% ± 25% and 939% ± 92%, respectively, and in tandem MS exhibited survival yields of 100% ± 0% and 72.6% ± 0.8% at -50 eV. 23 and 25 were also comparable in IE across several solvents, and combinations thereof, that are ubiquitous in liquid chromatography. Various salts of 25 were evaluated for cation effects, where the IE of 25 ranged from 939% ± 92% to 3195% ± 145% across K+, NH4+, Na+, and H+. Compared to tetra-n-butylammonium, tetra-n-butylphosphonium, and (4-methylphenyl)diphenylsulfonium cations, 25 displayed signal enhancements ranging from 136% ± 6% to 181% ± 14%, thereby making it an optimal candidate for CD development.

Bifunctional MOFs Nanozyme with Peroxidase Activity and Stimulus-responsive Fluorescent for Determination of Glyphosate

Establishing a fast and simple method for determining glyphosate (Glyp) is crucial for safeguarding the environment and protecting human well-being. In this work, a copper benzenedicarboxylate (CuBDC) metal-organic frameworks (MOFs) with peroxidase-like property and stimulus-responsive fluorescent was prepared by binding Cu2+ with terephthalic acid (TA). The presence of Glyp can coordination with Cu2+ ion and block the peroxidase-like properties of CuBDC, thereby suppressing the catalysis the oxidation of TA into fluorescent product 2-hydroxyterephthalic acid (HTA). Based on these facts, a simple, rapid and sensitive fluorescence detection strategy for Glyp was developed. The fluorescence decreases linearly in the 0.5-10 µg/mL Glyp concentration range, and the limit of detection was calculated to be 23.99 ng/mL. Furthermore, the dual-functional CuMOFs-based label-free strategy was effectively employed for detecting Glyp in river water samples. With good performance and practicability, this strategy provides a potential application in the convenient and reliable determination of Glyp in the environment.

A lateral strip assay for ultrasensitive detection of glyphosate in soybeans and corn

Glyphosate (GLY) is widely applied in agriculture and horticulture as a herbicide. The development of genetically modified plants has caused abuse of GLY, with excessive residues potentially causing harm to human health. Consequently, a novel method needs to be built to detect GLY in soybeans and corn. Computer simulation was used to design an excellent hapten which was used to produce an anti-GLY monoclonal antibody (mAb) with outstanding sensitivity and affinity, and its 50%-inhibitory concentration (IC50) was 128.59 ng mL-1. Afterwards, an immunochromatographic assay strip was developed based on the mAb. In soybeans and corn, the visual detection limits were 1 mg kg-1 and 0.2 mg kg-1, while the cut-off values were 50 mg kg-1 and 5 mg kg-1, respectively. The reliability of the strips was proved by the existing methods. Thus, a rapid method to detect GLY residues on-site in soybeans and corn was established.

Trimethylation Enhancement Using Diazomethane (TrEnDi) Enables Enhanced Detection of Glufosinate and 3-(Methylphosphinico)propionic Acid from Complex Canola Samples

Over the past century, agriculture practices have transitioned from manual cultivation to the use of an array of chemical herbicides for weed control including phosphinothricin, or glufosinate (GLUF). Consequently, the potential for long-term residual GLUF exposure in the food chain has increased, highlighting the need for improved analytical strategies for its detection, as well as the detection of its main breakdown product 3-(methylphosphinico)propionic acid (MPPA). Chemical derivatization strategies have been developed to improve the detection of GLUF and MPPA via liquid chromatography tandem mass spectrometry analyses. Herein, we employ trimethylation enhancement using diazomethane (TrEnDi) for the first time as a means to confer analytical advantages via quantitatively derivatizing these analytes into permethylated GLUF ([GLUFTr]+) and MPPA ([MPPATr+H]+). Comparing [GLUFTr]+ and [MPPATr+H]+ to underivatized counterparts, TrEnDi yields 2.8-fold and 1.7-fold improvements in reversed-phase chromatographic retention, respectively, while MS-based sensitivity is enhanced 4.1-fold and 11.0-fold, respectively. Successful analyte derivatization (with >99% yields) was further demonstrated on a commercial herbicide solution imparting consistent analytical enhancements. To investigate the benefits of TrEnDi in a bona fide agricultural scenario, simple aqueous extractions from distinct parts of field-grown canola plants were performed to quantify GLUF and MPPA before and after TrEnDi derivatization. In their underivatized forms, GLUF and MPPA were undetectable in all field samples, whereas [GLUFTr]+ and [MPPATr+H]+ were readily quantifiable using the same analysis conditions. Our results demonstrate that TrEnDi continues to be a useful tool to enhance the analytical characteristics of organic molecules that are traditionally difficult to detect.