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J Chromatogr B Analyt Technol Biomed Life Sci. 2017 Jan 1;1040:97-104. doi: 10.1016/j.jchromb.2016.12.013. Epub 2016 Dec 9.

Simultaneous determination and identity confirmation of thiodicarb and its degradation product methomyl in animal-derived foodstuffs using high-performance liquid chromatography with fluorescence detection and tandem mass spectrometry.

Author information

1
Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Yongbong-ro 77, Buk-gu, Gwangju 500-757, Republic of Korea.
2
Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, Seoul 143-701, Republic of Korea; Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211-Giza, Egypt. Electronic address: abdelaty44@hotmail.com.
3
Bio Control Research Center, Jeonnam Bioindustry Foundation, 495, Im-myeon, Gokseong-gun, Jeollanam-do, 516-942, Republic of Korea.
4
Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, Seoul 143-701, Republic of Korea.
5
Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Yongbong-ro 77, Buk-gu, Gwangju 500-757, Republic of Korea. Electronic address: jhshim@chonnam.ac.kr.

Abstract

A high-performance liquid chromatography-fluorescence detection method was developed for the simultaneous determination of thiodicarb and its degradation product methomyl in animal-derived food products, including chicken muscle, beef, pork, table eggs, and milk. Thiodicarb is known to degrade during analysis; therefore, a thorough investigation was carried out, revealing that thiodicarb degrades to methomyl immediately after spiking into a matrix of animal-derived food products. Consequently, thiodicarb was determined as the sum of the parent compound and methomyl. Samples were extracted with acetonitrile and sodium salts, and purified using solid-phase extraction (SPE). The limits of detection (LODs) and quantification (LOQs) were 0.0013 and 0.004mg/kg, respectively, for both analytes in various matrices. Seven-point external calibration curves were obtained, and they showed excellent linearity with determination coefficients (R2)≥0.999 for all tested matrices. The method was validated at three fortification levels (LOQ, LOQ×2, and LOQ×10) in triplicate with average recoveries ranging from 84.24 to 112.8% (for methomyl) and relative standard deviations (RSDs)≤6.5% in all matrices. The converted recoveries of thiodicarb in various matrices ranged from 74.80 to 107.80% with RSDs≤4.5%. The identities of both compounds in standard solutions and for recovery were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The developed method was further validated by accurate reproduction at another laboratory. Finally, the method was applied to market samples collected from different areas (and, in the case of milk, different brands), and none of the samples tested positive for thiodicarb or methomyl. In conclusion, the developed method can be successfully applied for a single-run analysis of thiodicarb and methomyl in livestock products.

KEYWORDS:

Degradation product; HPLC; Livestock products; Methomyl; Quantification; Simultaneous determination; Thiodicarb

PMID:
27978474
DOI:
10.1016/j.jchromb.2016.12.013
[Indexed for MEDLINE]

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