A new selective method for dimethylamine in water analysis by liquid chromatography using solid-phase microextraction and two-stage derivatization with o-phthalaldialdehyde and 9-fluorenylmethyl chloroformate

A new method is presented for the determination of DMA in water as its 9-fluorenylmethyl chloroformate (FMOC) derivative using solid-phase microextraction (SPME) and liquid chromatography. The method is based on the employment of SPME fibres coated with carbowax-templated resin (CW-TR) for analyte extraction and derivatization. The fibres were successively immersed in the samples, in a solution of o-phthalaldialdehyde and N-acethyl-l-cysteine (OPA-NAC) and finally, in a solution of FMOC. OPA-NAC reacted on the fibre with possible primary aliphatic amines present in the samples, particularly with PA which is a direct interferent in the determination of DMA with FMOC. In such a way, the formation of PA-FMOC during the second stage was prevented, and thus the method was selective for DMA. The proposed procedure was applied to the determination of DMA in the 1.0-10.0 μg/mL range. The method provided suitable linearity, accuracy and reproducibility, and limits of detection and quantification of 0.3 and 1.0 μg/mL, respectively. The applicability of the method for the determination of DMA in different types of water is shown.