Combination of Headspace Single‐Drop Microextraction, Microchip Electrophoresis and Contactless Conductivity Detection for the Determination of Aliphatic Amines in the Biodegradation Process of Seafood Samples

A new method for the efficient extraction and determination of volatile aliphatic amines by means of single-drop microextraction (SDME) in combination with microchip electrophoresis and contactless conductivity detection has been developed. An experimental approach for interfacing real world samples with chip electrophoresis is presented. The method consists of an optimized protocol for extraction via ultrasound assisted headspace SDME and the separation and determination of the target analytes with a novel microfluidic device. Five volatile, short-chained aliphatic amines, methylamine, dimethylamine, trimethylamine, diethylamine and triethylamine, were determined. The analytes were separated using a PMMA microchip with an 8.7 cm long separation channel and integrated thin-film gold electrodes for capacitively coupled contactless conductivity detection (C4D). The determinations were carried out in a His/MES buffer (His/MES ratio of 80 : 20 at pH 6.6). Various parameters for the extraction and determination of the target analytes were optimized and applied to complex sample matrices like shrimp. The five analytes could be separated in less than 40 s applying a separation voltage of 3.8 kV. A linear concentration dependence was found within the range from 0.1 to 10 ppm for the ethylamine species and from 0.5 to 10 ppm for the methylamines. The limits of detection were all well below 400 ng/mL. The proposed method is simple, quick, presents low levels of waste, works with small sample quantities and is suitable for quantification of aliphatic amines in seafood samples like shrimp or fish from where they are naturally developing upon biodegradation. In the present study the accelerated decay of shrimp tissue due to improper storage was monitored.