An effective methodology for simultaneous quantification of thiophanate-methyl, and its metabolite carbendazim in pear, using LC-MS/MS

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Vol. 1095; pp. 1 - 7
• Main Authors: Lee, Han Sol, Rahman, Md. Musfiqur, Chung, Hyung Suk, Kabir, Humayun, Yoon, Kwang-Sik, Cho, Soon-Kil, Abd El-Aty, A.M., Shim, Jae-Han
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.09.2018
• Subjects: Carbendazim; LC-MS/MS; Metabolite; Pear; Thiophanate-methyl; Thiophanate-methyl; LC-MS/MS; Pear; Metabolite; Carbendazim
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2018.07.010

Herein we have developed an optimized analytical method for the simultaneous quantification of a fungicide, thiophanate-methyl, and its metabolite, carbendazim, in pear cultivated under open-field conditions using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Due to the problem of partitioning associated with using acetonitrile and salts, methanol was used for sample extraction; the extract was then filtered using a vacuum filter, and cleaned-up using C18 QuEChERS bulk sorbent following dispersive solid-phase extraction (d-SPE) procedure. Since a common problem, “matrix effect”, associated with the matrix was observed in LC-MS/MS, calibration curves for both thiophanate-methyl and carbendazim were constructed in the matrix using seven different concentration levels. Excellent linearity was observed, with determinant coefficient (R2) ≥ 0.9990. The limits of quantification (LOQs) were ≤0.02 mg/kg, satisfactory in terms of the maximum residue limits. Methods were validated at two fortification concentrations (10 × LOQ and 50 × LOQ); the experiments were repeated three times for each level and the average recoveries were 75.00–84.92%, with the coefficient of variation (CV) being ≤5.78%. The developed analytical method was applied to pear samples previously sprayed with commercial thiophanate-methyl formulation four times on different days during pre-harvest treatment. The parent compound was converted to its metabolites and the total residues degraded continuously until harvest. The data obtained in this study could help set safety guidelines for thiophanate-methyl in pear. [Display omitted] •An analytical method was developed for simultaneous quantification of thiophanate-methyl and its metabolite, carbendazim, in pear using LC-MS/MS.•QuEChERS extraction method was unable to extract both compounds in pear.•Analytes were extracted using methanol and cleaned-up using C18 QuEChERS bulk sorbent.•The performance parameters were validated for satisfactory quantification.•The total residue was decreased with time till harvest.