Toward a comprehensive microextraction/determination unit: A chip silicon rubber polyaniline-based system and its direct coupling with gas chromatography and mass spectrometry.

An inexpensive silicon rubber-based chip was constructed by fabricating a triangle-shaped microcanal with a 135 μm width and 234 μm depth by laser ablation technique. The fabricated groove was sealed by a thin glass cover while two pieces of stainless-steel tubing were connected to each side of the canal. Then, a thin polyaniline film was synthesized on the walls of the canal by chemical oxidation using a syringe pump to deliver the relevant reagents. The microfluidic system was eventually connected to a gas chromatography-mass spectrometry. To evaluate the capability of the constructed microfluidic system, it was implemented to the analysis of submilliliter volumes of environmental samples spiked with the trace amounts of some pesticide residues. To show the applicability of the hyphenated system, the extraction/determination of triazines was implemented while only 500 μL sample with the limits of detection ranged from 0.2 to 0.5 ng/mL could be easily achieved. In addition, the influential extraction parameters such as sample volume, flow rate, and sample pH were optimized. Under the optimized conditions, the relative standard deviation values for double-distillated water sample spiked with the selected triazines at 250 ng/mL were 6.5-12.5% (n = 3).