Determination of aldehydes in water samples by coupling magnetism-reinforced molecular imprinting monolith microextraction and non-aqueous capillary electrophoresis

Abstract Excess 2, 4-dinitrophenylhydrazine (2, 4-DNPH) is often applied for the derivatization of aldehyde prior to the chromatographic analysis. However, the residual 2, 4-DNPH may cause background interference and limit the enrichment efficiency of trace aldehydes. To overcome the above bottle-neck problems, improve the extraction efficiency and omit the manipulation for changing the polarity of solvent for the hydrophobic analytes separation, a new method combining magnetism-reinforced in-tube solid phase microextraction (IT-SPME) technique with non-aqueous capillary electrophoresis (NACE) was developed. The monolithic extraction cartridge was prepared in situ inside a capillary and doped with magnetic molecular imprinting polymers (mMIPs). The selective and efficient extraction of the derived analytes with simultaneous removal of the superfluous derivatization agent was achieved owing to the combined effect of molecular imprinting and magnetism reinforcement. By coupling with NACE, the highly hydrophobic effluent can be analyzed directly. The LODs of the method are between 0.0032~0.0049 mg L−1 and the recoveries are between 87.3~99.8% for the tested aldehydes. The developed approach is sensitive enough for detection of surface (drinking) water. The aldehydes in real water samples have been detected by this method, showing results that are in good agreement with the standard SPE-HPLC method.