Development of immunosorbents for the analysis of forchlorfenuron in fruit juices by ion mobility spectrometry

Green synthesis of superhydrophilic resin/graphene oxide for efficient analysis of multiple pesticide residues in fruits and vegetables

The escalating use of pesticides on fruits and vegetables has raised concerns about potential health risks. Therefore, we developed a superhydrophilic resin/graphene oxide (SR/GO) with rich adsorption interactions using an eco-friendly synthetic approach. SR/GO demonstrated excellent hydrophilicity, ensuring optimal contact with aqueous sample matrices. The multiple adsorption interactions, including π-π conjugation, hydrogen bonding, and electrostatic adsorption, facilitated multi-pesticide residue co-extraction. The synthesized SR/GO was applied to a miniaturized centrifugation-accelerated pipette-tip extraction method, coupled with high-performance liquid chromatography. The optimized method exhibited low consumption (15.0 mg adsorbent), and high efficiency, with low detection limits (1.4-2.9 ng g-1) and high recoveries (75.3-113.0%). Water-compatible SR/GO, along with a miniaturized extraction process, showcases a potent analytical approach for pesticide residue analysis in fruits and vegetables. The significance of this method lies in its ability to ensure agricultural and food safety by using a low-cost and efficient multi-pesticide residue analytical strategy.

Sandwich-like CuNPs@AgNPs@PSB SERS substrates for sensitive detection of R6G and Forchlorfenuron

The development of a highly sensitive, synthetically simple and economical SERS substrate is technically very important. A fast, economical, sensitive and reproducible CuNPs@AgNPs@ Porous silicon Bragg reflector (PSB) SERS substrate was prepared by electrochemical etching and in situ reduction method. The developed CuNPs@AgNPs@PSB has a large specific surface area and abundant "hot spot" region, which makes the SERS performance excellent. Meanwhile, the successful synthesis of CuNPs@AgNPs can not only modulate the plasmon resonance properties of nanoparticles, but also effectively prolong the time stability of Cu nanoparticles. The basic performance of the substrate was evaluated using rhodamine 6G (R6G). (Detection limit reached 10-15 M, R2 = 0.9882, RSD = 5.3 %) The detection limit of Forchlorfenuron was 10 μg/L. The standard curve with a regression coefficient of 0.979 was established in the low concentration range of 10 μg/L -100 μg/L. This indicates that the prepared substrates can accomplish the detection of pesticide residues in the low concentration range. The prepared high-performance and high-sensitivity SERS substrate have a very promising application in detection technology.

Production of a Monoclonal Antibody for the Detection of Forchlorfenuron: Application in an Indirect Enzyme-Linked Immunosorbent Assay and Immunochromatographic Strip

In this study, a monoclonal antibody (mAb) specific to forchlorfenuron (CPPU) with high sensitivity and specificity was produced and designated (9G9). To detect CPPU in cucumber samples, an indirect enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold nanobead immunochromatographic test strip (CGN-ICTS) were established using 9G9. The half-maximal inhibitory concentration (IC₅₀) and the LOD for the developed ic-ELISA were determined to be 0.19 ng/mL and 0.04 ng/mL in the sample dilution buffer, respectively. The results indicate that the sensitivity of the antibodies prepared in this study (9G9 mAb) was higher than those reported in the previous literature. On the other hand, in order to achieve rapid and accurate detection of CPPU, CGN-ICTS is indispensable. The IC₅₀ and the LOD for the CGN-ICTS were determined to be 27 ng/mL and 6.1 ng/mL. The average recoveries of the CGN-ICTS ranged from 68 to 82%. The CGN-ICTS and ic-ELISA quantitative results were all confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with 84-92% recoveries, which indicated the methods developed herein are appropriate for detecting CPPU in cucumber. The CGN-ICTS method is capable of both qualitative and semiquantitative analysis of CPPU, which makes it a suitable alternative complex instrument method for on-site detection of CPPU in cucumber samples since it does not require specialized equipment.

Separation of Isomeric Metabolites and Gangliosides with High Performance (Drift Tube) Ion Mobility–Mass Spectrometry

The study of metabolites and gangliosides is increasingly important in drug discovery (1) and immunology (2). Accurate analysis of biologically relevant isomers is important because their structure affects their molecular properties. Typically, the isomers are separated using chromatography prior to mass spectrometry (MS) analysis. However, specialized chromatographic methods that distinguish isomers frequently require a complex setup and long runs. Techniques that allow accurate results to be acquired quickly and efficiently would be beneficial.

Identity, Synthesis, and Cytotoxicity of Forchlorfenuron Metabolites in Kiwifruit

Forchlorfenuron (CPPU) is a plant growth regulator widely used in kiwifruit production. Although research on the toxicological and environmental effects of CPPU is well-established, the nature and toxicological properties of its metabolites are much less well-known. Using high resolution mass spectrometry and nuclear magnetic resonance, the CPPU previously unidentified metabolites in Xuxiang and Jinyan kiwifruit were identified as N-(2-chloro-4-pyridinyl)-N'-(2-hydroxy-4-methoxyphenyl)-urea (metabolite 1) and N-phenyl-N'-4-pyridinylurea (metabolite 2, CAS: 1932-35-0). Their structures were confirmed by synthesis (metabolite 1) and by comparison with a commercial standard (metabolite 2). Quantitative studies demonstrate that CPPU and its metabolites are mainly retained in the kiwifruit peel, while the content is dependent on the nature of the peel surface, with the smoother peel of Jinyan kiwifruit retaining smaller amounts of the compound. Cell viability experiments in Caco2 and Lo2 cells show that the metabolites may have a lower cytotoxicity compared to the parent compound CPPU.

Comparative Pharmacokinetic Study of Forchlorfenuron in Adult and Juvenile Rats

Forchlorfenuron (CPPU) is a plant growth regulator extensively used in agriculture. However, studies on CPPU pharmacokinetics are lacking. We established and validated a rapid, sensitive, and accurate liquid chromatography-mass spectrometry method for CPPU detection in rat plasma. CPPU pharmacokinetics was evaluated in adult and juvenile rats orally treated with 10, 30, and 90 mg/kg of the compound. The area under the plasma drug concentration-time curve from 0 to 24 h (AUC), at the final time point sampled (AUC_0-t), and the maximum drug concentration of CPPU increased in a dose-dependent manner. The pharmacokinetic parameters AUC_0-t and absolute bioavailability were higher in the juvenile rats than in adult rats. The mean residence time and AUC_0-t of juvenile rats in the gavage groups, except for the 10 mg/kg dose, were significantly higher in comparison to those observed for adult rats (p < 0.001). The plasma clearance of CPPU in juvenile rats was slightly lower than that in the adult rats. Taken together, juvenile rats were more sensitive to CPPU than adult rats, which indicates potential safety risks of CPPU in minors.

Dissipation behavior, residue dynamics, and dietary risk assessment of forchlorfenuron in postharvest kiwifruits during simulated cold chain logistics and store shelf life

Forchlorfenuron (CPPU) is often applied during the cultivation of kiwifruit to produce larger fruit. To address degradation patterns of CPPU during simulated cold chain logistics and simulated shelf life of the fruit after harvest, appropriate storage methods and safe consumption behavior can be investigated. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry method was adopted to detect CPPU residues under different conditions. CPPU in kiwifruit stored at 6 °C had a half-life of 40.8-77.0 days. However, when kiwifruit was stored at 0 °C under simulated cold chain storage conditions, the half-life of CPPU was 63.0-115.5 days, implying that lower storage temperatures can reduce the degradation rate of CPPU. The residues of CPPU in kiwifruit pulp declined with time, and the reduction followed the first-order kinetics equation. More CPPU residues were present in the pulp of postharvest kiwifruit treated with exogenous ethylene than in the pulp of untreated kiwifruit. Thus, using exogenous ethylene for artificial ripening after harvest is not recommended. We determined that the appropriate cold chain storage temperature is 6 °C. It is recommended that the public select kiwifruit stored for at least 2 weeks. The estimated chronic and acute dietary risk quotients of CPPU are ≤ 0.79% and ≤ 0.11%, respectively. Therefore, it is highly unlikely that consumers will be poisoned by CPPU due to kiwifruit consumption. Our results provide scientific evidence regarding the adoption of appropriate kiwifruit storage methods and consumption behavior to enhance consumption safety.

One pot green synthesis of m-aminophenol-urea-glyoxal resin as pipette tip solid-phase extraction adsorbent for simultaneous determination of four plant hormones in watermelon juice

Plant hormones (PHs) are a type of pesticide that can potentially affect human health. Therefore, their quantitative detection is particularly important. In this study, a green and economic method for the simultaneous extraction and determination of four PHs, namely thidiazuron, forchlorfenuron, 1-naphthylacetic acid, and 2-naphthoxyacetic acid, in watermelon juice was developed by using m-aminophenol-urea-glyoxal resin as the adsorbent for pipette tip solid phase extraction (PT-SPE) coupled with liquid chromatography. The resin was synthesized via a simple (one pot hydrothermal synthesis) and green (ethanol as the solvent and glyoxal as crosslinking agent) process. The synthesized resin possesses multiple functional groups (hydroxyl, amino, and imino, among others), high adsorption capacity, larger specific surface area than the urea-glyoxal resin and m-aminophenol-glyoxal resin, and can be regenerated easily. The PT-SPE device is simple, cheap, and easy to obtain, and the adsorbent dosage is only 5.0 mg. The proposed method has a wide linear detection range, high recovery, good precision, and high sensitivity, and satisfies the measurement requirements for detecting trace levels of PHs in fruits and vegetables.

QuEChERS - Fundamentals, relevant improvements, applications and future trends

The Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method is a simple and straightforward extraction technique involving an initial partitioning followed by an extract clean-up using dispersive solid-phase extraction (d-SPE). Originally, the QuEChERS approach was developed for recovering pesticide residues from fruits and vegetables, but rapidly gained popularity in the comprehensive isolation of analytes from different matrices. According to PubMed, since its development in 2003 up to November 2018, about 1360 papers have been published reporting QuEChERS as extraction method. Several papers have reported different improvements and modifications to the original QuEChERS protocol to ensure more efficient extractions of pH-dependent analytes and to minimize the degradation of labile analytes. This analytical approach shows several advantages over traditional extraction techniques, requiring low sample and solvent volumes, as well as less time for sample preparation. Furthermore, most of the published studies show that the QuEChERS protocol provides higher recovery rate and a better analytical performance than conventional extraction procedures. This review proposes an updated overview of the most recent developments and applications of QuEChERS beyond its original application to pesticides, mycotoxins, veterinary drugs and pharmaceuticals, forensic analysis, drugs of abuse and environmental contaminants. Their pros and cons will be discussed, considering the factors influencing the extraction efficiency. Whenever possible, the performance of the QuEChERS is compared to other extraction approaches. In addition to the evolution of this technique, changes and improvements to the original method are discussed.