Development of QuEChERS extraction method for the determination of pesticide residues in cereals using DART-ToF-MS and GC-MS techniques. Correlation and quantification study

Recent advances in the application of direct analysis in real time-mass spectrometry (DART-MS) in food analysis

Direct analysis in real time-mass spectrometry (DART-MS) has evolved as an effective analytical technique for the rapid and accurate analysis of food samples. The current advancements of DART-MS in food analysis are described in this paper. We discussed the DART principles, which include devices, ionization mechanisms, and parameter settings. Numerous applications of DART-MS in the fields of food and food products analysis published during 2018-2023 were reviewed, including contamination detection, food authentication and traceability, and specific analyte analysis in the food matrix. Furthermore, the challenges and limitations of DART-MS, such as matrix effect, isobaric component analysis, cost considerations and accessibility, and compound selectivity and identification, were discussed as well.

High sensitivity on-site early warning system monitoring of pesticides by photo-induced fluorescence

This paper describes the prototype of an on-site High Sensitivity Early Warning Monitoring System, using Photo-Induced Fluorescence, for pesticide monitoring in natural waters (HSEWPIF). To obtain a high sensitivity, the prototype was designed with four main features. Four UV LEDs are used to excite the photoproducts at different wavelengths and select the most efficient one. Two UV LEDs are used simultaneously at each wavelength to increase the excitation power and then the fluorescence emission of the photoproducts. High-pass filters are used to avoid the saturation of the spectrophotometer and to increase the signal-to-noise ratio. The HSEWPIF prototype also employs UV absorption to detect any occasional increase of suspended and dissolved organic matter, which could disrupt the fluorescence measurement. The conception of this new experimental set-up is explained and described, then analytical applications are carried out online for the determination of fipronil and monolinuron. We obtained a linear calibration range from 0 to 3 μg mL^-1 with limits of detection of 1.24 ng mL^-1 for fipronil and 0.32 ng mL^-1 for monolinuron. A mean recovery of 99.2% for fipronil and 100.9% for monolinuron show that the method is accurate, moreover a standard deviation of 1.96% for fipronil and 2.49% for monolinuron show that the method is repeatable. Compared to other methods for the determination of pesticides by photo-induced fluorescence, the HSEWPIF prototype has good sensitivity with better limits of detection, and good analytical performances. These results show that HSEWPIF can be used for monitoring pesticide in natural waters to protect industrial facilities against accidental contamination.

Quantitative Modeling of the Degradation of Pesticide Residues in Wheat Flour Supply Chain

Pesticide residues in grain products are a major issue due to their comprehensive and long-term impact on human health, and quantitative modeling on the degradation of pesticide residues facilitate the prediction of pesticide residue level with time during storage. Herein, we tried to study the effect of temperature and relative humidity on the degradation profiles of five pesticides (carbendazim, bensulfuron methyl, triazophos, chlorpyrifos, and carbosulfan) in wheat and flour and establish quantitative models for prediction purpose. Positive samples were prepared by spraying the corresponding pesticide standards of certain concentrations. Then, these positive samples were stored at different combinations of temperatures (20 °C, 30 °C, 40 °C, 50 °C) and relative humidity (50%, 60%, 70%, 80%). Samples were collected at specific time points, ground, and the pesticide residues were extracted and purified by using QuEChERS method, and then quantified by using UPLC-MS/MS. Quantitative model of pesticide residues was constructed using Minitab 17 software. Results showed that high temperature and high relative humidity accelerate the degradation of the five pesticide residues, and their degradation profiles and half-lives over temperature and relative humidity varied among pesticides. The quantitative model for pesticide degradation in the whole process from wheat to flour was constructed, with R² above 0.817 for wheat and 0.796 for flour, respectively. The quantitative model allows the prediction of the pesticide residual level in the process from wheat to flour.

Rapid, novel screening of toxicants in poison baits, and autopsy specimens by ambient mass spectrometry

Animal poisoning and dissemination of baits in the environment have public health and ethological implications, which can be followed by criminal sanctions for those responsible. The reference methods for the analysis of suspect baits and autopsy specimens are founded on chromatographic-based techniques. They are extremely robust and sensitive, but also very expensive and laborious. For this reason, we developed an ambient mass spectrometry (AMS) method able to screen for 40 toxicants including carbamates, organophosphate and chlorinated pesticides, coumarins, metaldehyde, and strychnine. Spiked samples were firstly purified and extracted by dispersive solid phase extraction (QuEChERS) and then analyzed by direct analysis in real time high-resolution mass spectrometry (DART-HRMS). To verify the performance of this new approach, 115 authentic baits (n = 59) and necropsy specimens (gastrointestinal content and liver, n = 56) were assessed by the official reference methods and combined QuEChERS-DART-HRMS. The agreement between the results allowed evaluation of the performances of the new screening method for a variety of analytes and calculation of the resultant statistical indicators (the new method had overall accuracy 89.57%, sensitivity of 88.24%, and a specificity of 91.49%). Taking into account only the baits, 96.61% of overall accuracy was achieved with 57/59 samples correctly identified (statistical sensitivity 97.50%, statistical specificity 94.74%). Successful identification of the bitter compound, denatonium benzoate, in all the samples that contained rodenticides (28/28) was also achieved. We believe initial screening of suspect poison baits could guide the choice of reference confirmatory methods, reduce the load in official laboratories, and help the early stages of investigations into cases of animal poisoning.

A critical comparison between an ultra-high-performance liquid chromatography triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method and an enzyme assay for anti-cholinesterase pesticide residue detection in cereal matrices

Analytical method development for the control of pesticide residues occurring in significant dietary foodstuffs is of utmost importance considering their potential impact on consumer health and food market sustainability. Depending on the purpose, either instrumental analysis, mainly chromatographic methods, or screening assays, mostly using biorecognition affinity, are commonly used, featuring different advantages and drawbacks. To practically compare these two different types of analytical strategies, we applied them for the detection of (i) 97 organophosphate (OP) and carbamate (CM) pesticide residues in wheat flour and (ii) carbofuran (a carbamate insecticide) in wheat, rye and maize flour samples. Regarding high-end analysis, an ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method was developed and validated achieving low limits of quantification (LOQs, from 0.002 to 0.040 mg kg^-1) and a short chromatographic run (12 min). In terms of bioanalytical methods, a fast (17 min) and cost-efficient (∼0.01€ per sample) acetylcholinesterase (AChE) microplate assay for carbofuran screening was utilized. Importantly, carbofuran was the strongest of the 11 OP and CM tested pesticides achieving a half maximal inhibitory concentration (IC₅₀) of 0.021 μM whilst the assay detectability was at the parts per billion level in all three cereal matrices. Based on the attained results, a critical discussion is presented providing the analytical merits and bottlenecks for each case and a wider outlook related to the application of analytical methods in the food safety control analytical scheme.

Routine analysis of pesticides in foodstuffs: Emerging ambient ionization mass spectrometry as an alternative strategy to be on your radar

Pesticides residues in foodstuffs are longstanding of great concern to consumers and governments, thus reliable evaluation techniques for these residues are necessary to ensure food safety. Emerging ambient ionization mass spectrometry (AIMS), a transformative technology in the field of analytical chemistry, is becoming a promising and solid evaluation technology due to its advantages of direct, real-time and in-situ ionization on samples without complex pretreatments. To provide useful guidance on the evaluation techniques in the field of food safety, we offered a comprehensive review on the AIMS technology and introduced their novel applications for the analysis of residual pesticides in foodstuffs under different testing scenarios (i.e., quantitative, screening, imaging, high-throughput detection and rapid on-site analysis). Meanwhile, the creative combination of AIMS with high-resolution mass analyzer (e.g., orbitrap and time-of-flight) was fundamentally mentioned based on recent studies about the detection and evaluation of multi-residual pesticides between 2015 and 2021. Finally, the technical challenges and prospects associated with AIMS operation in food industry were discussed.