A salt-assisted graphene oxide aggregation method for the determination of dimethylamine and trimethylamine by ion chromatography with conductivity detection

A simple and organic solvent-free solid phase microextraction method using salt-assisted graphene oxide (GO) combined with ion chromatography-conductivity detection was developed for analysis of dimethylamine (DMA) and trimethylamine (TMA). The GO sheets were uniformly dispersed in aqueous solutions for efficient adsorption of DMA and TMA, and then aggregated with the addition of NaCl by electrostatic double layer attraction. DMA and TMA were eluted by using methanesulfonic acid and separated with GO aggregation by centrifuging. Finally, the analytes were injected into the ion chromatography system for analysis. The parameters influencing the extraction efficiency including sample pH, GO amount, adsorption time and NaCl concentration were investigated. Under the optimized conditions, the obtained limits of detection were 0.012 mg L-1 for DMA and 0.035 mg L-1 for TMA. The relative standard deviations were smaller than 3.8% for five successive measurements of 0.20 mg L-1 DMA and TMA. The proposed method was successfully applied to the analysis of DMA and TMA with recoveries ranging from 84 to 106% for tap water and river water samples.