Food Adulteration by Granular Formulation of Carbamates for Animal Poisoning: Chromatographic Determination and Vibrational Microspectroscopy

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BACKGROUND: Carbamates have been used in intentional poisoning cases to cause death in both humans and animals. Granulated material containing carbamate pesticides is often applied to the victim's food, water, or drink. Toxicological analysis is essential to confirm such cases. OBJECTIVE: This study aims to identify and quantify carbamates (methomyl, aldicarb, propoxur, carbofuran, and carbaryl) present in granular formulations used to adulterate food, through the application of chromatographic and vibrational microspectroscopic techniques. METHODS: Thin-layer chromatography (TLC), liquid chromatography with diode array detector (LC-DAD), gas chromatography-mass spectrometry (GC-MS), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and Raman microspectroscopy were performed. An aliquot of granular formulation was manually separated for chromatographic methods; dilutions were employed as test material treatment, while vibrational microspectroscopy techniques used raw material for toxicological analysis. A material similar to a shredded sausage containing suspected granular formulation was evaluated in chromatographic tests, and carbofuran was determined. RESULTS: The proposed TLC methodology for identifying carbamates proved unfeasible due to insufficient chromatographic separation. The LC-DAD method was fully validated with success for methomyl, aldicarb, propoxur, carbofuran, and carbaryl, revealing a concentration of 744 µg/g of carbofuran in the suspected material, which was further confirmed by GC-MS. Raman microspectroscopy was not precise enough for carbamate identification, but ATR-FTIR demonstrated high specificity and robustness in identifying carbamate pesticides present in the test material. CONCLUSIONS: This study allowed determining the profile of carbamate pesticides in granular material when present in adulterated food/feed. To isolate the granules manually reduces the carrying of matrix interferents from food and/or feed. Furthermore, the techniques applied require only the raw material or its diluted versions, avoiding steps, high consumption of organic solvents, and reducing analysis time and cost. HIGHLIGHTS: LC-DAD was successfully validated for multiple carbamates. Minimal test material prep reduces solvent use, analysis time, and costs.