Magnetic solid-phase extraction followed by high performance liquid chromatography for determination of hexanal and heptanal in human urine

In this work, a new magnetic solid-phase extraction (MSPE) method based on C8-amine-Fe3O4 magnetic nanoparticles (MNPs) was developed for the determination of aldehyde biomarkers (hexanal and heptanal) in human urine samples. Hexanal and heptanal were derivatized with 2,4-initrophenylhydrazine (DNPH) in an acidic solution and then the formed aldehyde derivatives were extracted by the MNPs. After eluting and simple magnetic separation, the supernatant containing the two target analytes was transferred for HPLC analysis. The effects of various experimental parameters on the derivatization and extraction efficiency were investigated and optimized. Under the optimal conditions, good linearity was obtained in the concentration range of 0.005-5 mu mol L-1 (r > 0.9982). The limits of detection (LOD) for hexanal and heptanal were 1.87 and 0.78 nmol L-1 respectively. The average recoveries of urine samples of healthy humans ranged from 82.5% to 99.4% with the inter- and intra-day precisions (n = 6) less than 8.4%. Because of the excellent magnetic responsibility and high dispersibility of the MNPs, the proposed method was shown to be simple and rapid. Besides, this method possesses advantages such as low-cost, efficiency and good reproducibility.