Modified QuEChERS as a novel sample preparation method for analysis of N-nitrosodiethanolamine in shampoo by high performance liquid chromatography

Abstract

This study sought to develop a novel method for the trace analysis of N-nitrosodiethanolamine (NDELA) in shampoos inspired by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction, followed by an RP-HPLC method with a water-rich mobile phase. To improve the extraction recovery of NDELA and clean-up efficiency of the shampoo matrix, effective parameters of the QuEChERS method including sample amount, sorbent type and amount, solvent type and amount, as well as salt amount were optimized. The obtained results showed that using primary secondary amine and C18 accompanied by silica as a polar sorbent led to a much cleaner chromatogram with a lower baseline drift without significant decrease in the extraction recovery of NDELA. Under optimum conditions, satisfactory extraction recovery of NDELA in shampoo (79 ± 3%) was achieved. The concentration range of the calibration curve was 5–500 ng mL⁻¹ with a regression coefficient of 0.9993. Furthermore, the method's limits of detection (LOD_m) and quantification (LOQ_m) were 14 and 42 μg kg⁻¹ respectively. The intra- and inter-day accuracy and precision of the proposed method yielded relative recoveries of 98–101% and a relative standard deviation of less than 5% respectively. Finally, the developed method was applied to determine the occurrence of NDELA in various shampoo samples, and the obtained results were confirmed using liquid chromatography coupled with triple quadrupole mass spectrometry.