Analysis of N-methyl-2-pyrrolidone and its hydroxy metabolite at low concentration level in water samples using...

N-methyl-2-pyrrolidone (NMP) is a synthetic organic compound used as a solvent in several industrial processes such as battery and cosmetics production. There are growing concerns regarding the toxicity of NMP in the environment. We present for the first time a liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the determination of NMP and its hydroxy metabolite (5‑hydroxy-N-methyl-2-pyrrolidone, 5-OHNMP) in water at trace concentration (< 1.0 ng/mL). The HPLC separation was carried out on an aqueous mixed-mode column packed with C18 and anion exchange particles that enabled appropriate retention for both compounds. Quick sample preparation was performed by mixing isotopically labelled internal standards with the samples, followed by extraction with ethyl acetate in the presence of a QuEChERS salt mixture. After eliminating the use of plasticware from the entire sample treatment process, the target analytes could be detected at the 0.1 ng/mL level. The further reducing of the limit of quantification (LOQ) in real samples was limited by the cross contamination of NMP originating from the equipment used for the analysis. The method was validated between the 0.1 ng/mL and 10 ng/mL levels and the recovery ranged from 101 % to 109 % with high precision (RSD = 1.69 % - 7.34 %), with the exception for NMP at 0.10 ng/mL (RSD% = 24.7 %). The method was applied to the analysis of NMP in thirty-five surface and groundwater samples.