Identification and characterization of impurities in an insecticide, commercial chlorantraniliprole using liquid chromatography–tandem mass spectrometry

Abstract

RationaleEnsuring the global safety and effectiveness of agrochemicals has become imperative. An in‐depth understanding of impurity profiles of products is crucial, especially for high‐demand agrochemicals, where impurities may be more toxic and persistent than original agrochemicals. This study focuses on the detection and identification of impurities in a commercial chlorantraniliprole (CAP), an anthranilic diamide class broad‐spectrum insecticide.MethodsCommercial CAP was collected from an agrochemical supplier in India and was analyzed using a high‐performance liquid chromatography‐photodiode array (HPLC‐PDA) (Agilent 1260; wavelength, 220 nm) with a Zorbax RP SB‐C18 (250 × 4.6 mm, 5 μm) column and liquid chromatography–mass spectrometry (LC–MS) (Agilent 6545 quadrupole time of flight (Q‐TOF)) techniques to identify the impurities. The impurities were isolated by preparative HPLC using a Zorbax‐DB C18 (250 × 9.4 mm, 5 μm) column. liquid chromatography– tandem mass spectrometry (LC–MS/MS) experiments (Q‐TOF) were performed on CAP and its impurities to obtain their structural data.ResultsHPLC‐PDA analysis of CAP showed four major impurities (IM‐1 to IM‐4) ranging from 0.76% to 4.1%. The positive ion electrospray ionization (ESI) mass spectra of CAP and its impurities showed dominant [M + H]+ ions in addition to [M + Na]+, [M + K]+, and [2M + Na]+ ions. High‐resolution mass spectrometry (HRMS) data provided the elemental composition of the compounds, and isotopic distribution patterns revealed the number of Cl and/or Br atoms present in them. The structures of impurities were proposed based on the LC–MS/MS) data and further confirmed by nuclear magnetic resonance (NMR) data on isolated impurities/synthesis.ConclusionThe quality and impurities of CAP, a popular insecticide, must be assessed and described for its efficacy and safety. In this study, four impurities of CAP were detected using HPLC and successfully characterized using LC‐HRMS, LC–MS/MS, and NMR data. The method is useful for verifying the purity of CAP as well as helping in the identification of its possible impurities.