Determination of Paraquat Residues in Palm Oil by High‐Performance Liquid Chromatography with UV and Tandem Mass Spectrometry

Abstract

This paper describes a method for determination of paraquat residues in palm oil products by liquid chromatography with ultraviolet detector (HPLC‐UV) and liquid chromatography with tandem mass spectrometry (LC‐MS/MS). The sample (5 g) is extracted with 10 mL ethyl acetate/deionized water and purified through a Strata X‐CW anion exchange solid‐phase extraction (SPE) cartridge. While using HPLC, the chromatographic separation is carried out using a reverse phase pentafluorophenyl column with the mobile phase comprising 95% water and 5% methanol with 0.2% trifluoroacetic acid (TFA). Analysis on a hydrophilic interaction liquid chromatography (HILIC) column did not require TFA. The limits of detection (LOD) and quantification (LOQ) for HPLC‐UV analysis are 0.025 μg mL−1 and 0.05 μg mL−1, respectively. The LC‐MS/MS method did not require an SPE clean‐up and provided an LOQ of 0.01 μg mL−1. The percentage recoveries at the fortification levels of 0.1, 0.05, and 0.01 mg kg−1 are between 70 and 120% with the precision RSD <20%. The matrix effects in LC‐MS/MS analysis are from 40 and 65%, while the recoveries are corrected by paraquat‐D6 as an internal standard. The optimized and validated method fulfills the criteria of DG‐SANTE guidelines and complied with the MRL requirements.Practical Applications: A simple method is reported for the quantitative analysis of paraquat in palm oil products by using HPLC equipped with UV and MS/MS detections. The optimized method fulfills the Codex guidelines on performance criteria for methods of analysis for the determination of pesticide residues in food and feed requirements and meet the Codex maximum residue level (CODEX MRL) in terms of analytical sensitivity and passed all criteria of European Commission's DG‐SANTE guideline (SANTE/11813/2017) of analytical quality control. The method will be useful for regulatory enforcement as well as high throughput commercial residue testing purposes.An efficient residue analysis method is reported for determination of paraquat in palm oil by HPLC‐UV and LC‐MS/MS techniques. The optimized method provides acceptable performance in terms of recoveries and precision as per the SANTE/11813/2017 guideline. The method sensitivity complies with the Codex MRL. The method is suitable for monitoring and enforcement of paraquat residues in a range of palm oil products. It holds promise for routine use in regulatory as well as commercial residue testing laboratories.