Analytical control of residues of the herbicide trifluralin in the assessment of the food safety

Abstract

Introduction. Trifluralin is a systemic herbicide of the chemical class of dinitroaniline derivatives. During monitoring studies, trifluralin was detected in carrots produced in the Russian Federation. Since trifluralin-based pesticides are not approved for the use in the Russian Federation, residual amounts of the substance are not typical for this crop. To check the contamination of carrots with a pesticide not typical for this crop, confirmatory qualitative and quantitative studies were carried out. Purpose of the work. Increasing the efficiency of identification and reliability of quantitative results when monitoring food products for safety when performing confirmatory analytical studies using the example of determining trifluralin in carrots to assess the safety of food products intended for the consumer. Materials and methods. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was used to identify and quantify trifluralin. Samples were prepared for analysis using the QuEChERS method. Identification was carried out by multiple reaction monitoring (MRM) using a triple quadrupole mass spectrometer using two to four MRM transitions (m/z): 306,1→264,0; 264,0→206,0; 264,0→188,0; 264,0→160,1. Matrix-matched calibration was used for quantitation. Results. The effectiveness of screening studies when monitoring food products using the GC-MS/MS method can be significantly elevated by increasing the number of MRM transitions (at least 3), controlling the reference retention time of the substance, and maintaining the ratio of confirmatory ions. To obtain a reliable quantification of trifluralin content in carrots, the use of a matrix-matched calibration is recommended. Limitation. In the study, only carrots were considered as food products. Conclusion. Confirmation of test results is especially important when determining pesticide residues that are not normally found in a given matrix, or when it is suspected that the maximum permissible level may be exceeded. When conducting a screening study and detecting a food contaminant, contamination of the product can only be reported in advance. Next, a confirmatory analysis is required using a validated quantitative method, including an appropriate calibration procedure. In quantitative analysis, the presence of matrix sample components can cause problems due to sample suppression/enhancement phenomena. Matrix-aware calibration has been shown to be effective in compensating for matrix effects.