Monitoring 432 potential pesticides in tomatoes produced and commercialized in Souss Massa region-Morocco, using LC-MS/MS and GC-MS/MS.

In this work, we monitored 432 pesticide residues in 39 tomato samples (cherry tomato) obtained from local markets in Souss Massa region-Morocco. We used a QuEChERS combined with LC-MS/MS and GC-MS/MS, and the method was validated based on SANTE 11312/2021 guideline. The limits of quantification (LOQ) obtained for most of the pesticides analyzed are at the limit with default EU MRLs or well below other EU MRLs. Recoveries (between 70 and 120%) and RSDs (≤20%) are satisfactory for more than 95% of the analytes at spiking level of 0.01 mg/kg and more than 97% at 0.1 mg/kg. The results indicated that 22 out of 39 tomato samples are positives and the most of our samples had levels lower than the maximum residue levels (MRLs) with average concentrations between 0.011 and 0.156 mg/kg. The most found pesticides were azoxystrobin and difenoconazole in tomato (7 samples). Only buprofezin (0.095 mg/kg) was found above the EU MRLs (0.01 mg/kg). Also, banned pesticides namely benalaxyl, spirodiclofen and imidacloprid have been detected. The results of our study confirm the previous findings and gives insights on the occurrence of different pesticides in tomato samples from Souss Massa region-Morocco.

Modified-QuEChERS-LC/MS method for the analysis of aflatoxins and ochratoxin A in coriander seeds.

Coriander seeds consumption, like other spices, has increased due to its culinary use, medicinal benefits, and its essential oil. However, there are few reports in the scientific literature on the prevalence of mycotoxins in this spice. In this report, an easy and simple method was proposed for the determination of the aflatoxin group (AFB1, AFB2, AFG1, and AFG2) and ochratoxin A (OTA) in coriander seeds. The recoveries of analytes ranged from 72 to 102% in spiked samples (0.5-5 µg/kg), with RSD below 11%. The limits of quantification (LOQ) are between 0.12 and 0.5 µg/kg. The proposed method represents an improvement compared to previous studies. It was tested for the determination of 13 samples, proving that it is fast, efficient, and sensitive. Only OTA was identified in four samples, all at levels lower than the European limits defined for some spices (0.88 and 5.4 µg/kg). Such methods are needed for monitoring these toxins in this spice to ensure consumer safety and provide insight into their occurrence.

Mycotoxins in food: a review on liquid chromatographic methods coupled to mass spectrometry and their experimental designs.

The development of a multi-mycotoxins method using LC-MS/MS is necessary and it is clear that the development of such method involves many compromises in the choice of the different parameters. This review summarizes applications using conventional experimental designs and some recent studies using response surface methodology (RSM) as a mathematical modeling tool for the optimization of extraction procedures. The authors also discuss pros and cons of the different procedures. To our knowledge, it is the first review on experimental design for the development of multi-mycotoxin methods. This review could be useful in the development and optimization of LC-MS/MS methods with the aim of describing experimental design and variables (factors) that are likely to affect sensitivity and specificity.

A simple extraction method with no lipid removal for the determination of aflatoxins in almonds by liquid chromatography tandem-mass spectrometry (LC-MS/MS).

The present study describes a simple and rapid method for the determination of aflatoxins in almonds using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Aflatoxins were extracted using a modified QuEChERS method with little sample preparation, excluding the use of laborious purification procedures. Extracts were frozen overnight to separate the majority of lipids. The method was successfully validated for almonds. Linearity was demonstrated in the range 0.125-20 µg/kg. Limits of quantification (LOQ) ranged from 0.34 to 0.5 µg/kg. Matrix effect was not significant for the aflatoxins. Satisfactory recoveries were obtained at spike levels below 1 µg/kg and between 1 and 10 µg/kg. Relative standard deviations (RSDs) of repeatability and reproducibility were below 15%. The method was successfully tested with two proficiency tests in almond powder and peanut paste, with acceptable z-scores (-2 ≤ z ≤ 2). Only one of 11 local almond samples contained detectable aflatoxins, at concentrations below the maximum permitted level.

Chemometric Approach Based on Accuracy Profile and Data Chronological Distribution as a Tool to Detect Performance Degradation and Improve the Analytical Quality Control for Aflatoxins' Analysis in Almonds Using UPLC-MS/MS.

One of the main objectives of routine laboratories is the development of simple and reliable methods as well as meeting fit-for-purpose criteria for regulatory surveillance. In this study, the accuracy profiles and the evaluation of the distribution of results in the case of aflatoxins in almonds have been performed using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method consists of designing the experiment and using certified reference material (CRM) to evaluate the bias, to calculate the combined uncertainty, and to construct the control charts. Good sensitivity (limit of quantifications (LOQs) 0.34-0.5 µg/kg) and recovery (between 82 and 107%) were achieved. The proposed method was successfully tested with a proficiency test in almond powder with acceptable z scores (-2 ≤ z ≤ 2). The results provided direct evidence for the proper functioning and stability of the whole analytical protocol, allowing acceptable combined uncertainty.

A facile extraction method followed by UPLC-MS/MS for the analysis of aflatoxins and ochratoxin A in raw coffee beans.

A UPLC-MS/MS method was developed and validated for the determination of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2) and ochratoxin A (OTA) in raw coffee samples. Mycotoxins were extracted using a modified QuEChERS method with little sample preparation excluding clean-up and enrichment procedures. Linearity was demonstrated for the five mycotoxins in the range 0.125-20 µg/kg. This method shows negligible matrix effect for individual concentrations, thus allowing the use of an external standard procedure. Limits of quantification (LOQ) ranged from 0.45 to 1 µg/kg. Recoveries between 63% and 89% were achieved. The intra- and inter-day precisions were lower than 15%. The applicability of the method was demonstrated, taking into account fitness for purpose, with simplicity, reliability, low costs and environmental friendliness. The results show that 3 out of 4 samples were contaminated with OTA.

Molecularly imprinted polymer cartridges coupled to high performance liquid chromatography (HPLC-UV) for simple and rapid analysis of fenthion in olive oil.

A combination of molecular modelling and a screening of the library of non-imprinted polymers (NIPs) was used to identify acrylamide as a functional monomer with high affinity towards fenthion, organophosphate insecticide, which is frequently used in the treatment of olives. A good correlation was found between the screening tests and modelling of monomer-template interactions performed using a computational approach. Acrylamide-based molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were thermally synthesised in dimethyl formamide (porogen) using ethylene glycol dimethacrylate as a cross-linker and 1,1-azo-bis (isobutyronitrile) as an initiator. The chemical and physical properties of the prepared polymers were characterised. The binding of fenthion by the polymers was studied using solvents with different polarities. The developed MIP showed a high selectivity towards fenthion, compared to other organophosphates (dimethoate, methidathion malalthion), and allowed extraction of fenthion from olive oil samples with a recovery rate of about 96%. The extraction of fenthion using MIPs was much more effective than traditional C18 reverse-phase solid phase extraction and allowed to achieve a low detection limit (LOD) (5 µg L(-1)).

Computational and experimental investigation of molecular imprinted polymers for selective extraction of dimethoate and its metabolite omethoate from olive oil.

This work presents the development of molecularly imprinted polymers (MIPs) for the selective extraction of dimethoate from olive oil. Computational simulations allowed selecting itaconic acid as the monomer showing the highest affinity towards dimethoate. Experimental validation confirmed modelling predictions and showed that the polymer based on IA as functional monomer and omethoate as template molecule displays the highest selectivity for the structurally similar pesticides dimethoate, omethoate and monocrotophos. Molecularly imprinted solid phase extraction (MISPE) method was developed and applied to the clean-up of olive oil extracts. It was found that the most suitable solvents for loading, washing and elution step were respectively hexane, hexane-dichloromethane (85:15%) and methanol. The developed MIPSE was successfully applied to extraction of dimethoate from olive oil, with recovery rates up to 94%. The limits of detection and quantification of the described method were respectively 0.012 and 0.05 µg g(-1).

Acetylcholinesterase immobilized on magnetic beads for pesticides detection: application to olive oil analysis.

This work presents the development of bioassays and biosensors for the detection of insecticides widely used in the treatment of olive trees. The systems are based on the covalent immobilisation of acetylcholinesterase on magnetic microbeads using either colorimetry or amperometry as detection technique. The magnetic beads were immobilised on screen-printed electrodes or microtitration plates and tested using standard solutions and real samples. The developed devices showed good analytical performances with limits of detection much lower than the maximum residue limit tolerated by international regulations, as well as a good reproducibility and stability.

Molecular imprinting solid phase extraction for selective detection of methidathion in olive oil.

A specific adsorbent for extraction of methidathion from olive oil was developed. The design of the molecularly imprinted polymer (MIP) was based on the results of the computational screening of the library of polymerisable functional monomers. MIP was prepared by thermal polymerisation using N,N'-methylene bisacrylamide (MBAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The polymers based on the itaconic acid (IA), methacrylic acid (MAA) and 2-(trifluoromethyl)acryl acid (TFMAA) functional monomers and one control polymer which was made without functional monomers with cross-linker EGDMA were also synthesised and tested. The performance of each polymer was compared using corresponding imprinting factor. As it was predicted by molecular modelling the best results were obtained for the MIP prepared with MBAA. The obtained MIP was optimised in solid-phase extraction coupled with high performance liquid chromatography (MISPE-HPLC-UV) and tested for the rapid screening of methidathion in olive oil. The proposed method allowed the efficient extraction of methidathion for concentrations ranging from 0.1 to 9 mg L(-1) (r(2)=0.996). The limits of detection (LOD) and quantification (LOQ) in olive oil were 0.02 mg L(-1) and 0.1 mg L(-1), respectively. MIPs extraction was much more effective than traditional C18 reverse-phase solid phase extraction.