A miniaturized GC detector employing μ-arc emission spectrometry with sub-nanogram detection using air carrier gas

This study presents a gas chromatographic detector using alternating current (AC) discharged in air to generate μ-arc at atmosphereic pressure. This air-based μ-arc emission detector (μ-AED) was assembled by two stainless-steel syringe needles inside a quartz tube. The length of μ-arc (i.e., distance of discharge) measures 550 μm. The organic compounds with various functional groups were chromatographically separated and fed into the μ-AED. The intensity changes in the emission spectrum were recorded as these compounds passing through the μ-arc. When organic compounds pass through the μ-arc, the changes in emission intensity could go either increase or decrease depending on the input power and underlying mechanisms. It was found that when operating the μ-arc at relatively low power, organic samples present as negative peaks, and better S/N ratio were obtained. The detection limits (3σ/s) range from 209 pg for n-butyl acetate to 552 pg for 1-chloropentane. A selectivity study reveals that μ-AED is more sensitive to oxygen-containing and aromatic compounds. The μ-AED developed in this study demonstrates the simplest design with reasonable miniaturization. The direct discharge in air makes this μ-AED suitable for future application with μ-GC which uses scrubbed air as carrier gas and eliminates bulky gas cylinders.