Simultaneous determination of four aliphatic amines in aquatic products by ultrasound-assisted dispersive liquid–liquid microextraction coupled with high performance capillary electrophoresis

Abstract

A simple, rapid, inexpensive and efficient method based on ultrasound-assisted dispersive liquid–liquid microextraction (UDLLME) after pre-column derivatization coupled with high performance capillary electrophoresis (HPCE) has been developed for determination of methylamine (MA), ethylamine (EA), dimethylamine (DMA) and diethylamine (DEA) in aquatic products. The aliphatic amines were derivatized with 9-fluorenyl methyl chloroformate (FMOC-Cl) in alkaline aqueous solution and then the derivatives were extracted by ultrasound-assisted liquid–liquid microextraction (UDLLME) with trichloromethane. The factors affecting the derivatization and extraction efficiencies were investigated in detail. The electrophoresis separation was performed in an uncoated fused-silica capillary (50 cm × 50 μm i.d.) with an effective length of 41 cm; 25 mmol L⁻¹ sodium tetraborate containing 15 mmol L⁻¹ sodium dodecyl sulfate (SDS) was used as running buffer; the applied voltage was 20 kV; the separation temperature was set to 25 °C; the UV detection wavelength was set at 265 nm. Four derivatized products of aliphatic amines could be completely separated within 7 min. The calibration curves were linear in the range of 0.5 to 12.5 mg L⁻¹ for MA and DMA, and 1.0 to 25 mg L⁻¹ for EA and DEA with the correlation coefficients ranging from 0.9984 to 0.9994. The limits of detection (LODs) and limits of quantification (LOQs) of the method were in the ranges of 0.028–0.16 mg kg⁻¹ and 0.095–0.53 mg kg⁻¹, respectively. The enrichment factors ranged from 42 to 68 for the four derivatives. The recoveries of the method were in the range of 72.8–97.0%, with the intraday relative standard deviations (RSDs) of the peak area in the range of 2.80–4.61%. This method has been successfully applied to the analysis of the four aliphatic amines in aquatic products.