Towards an on-chip gas chromatograph: the development of a gas injector and a dc plasma emission detector

Work is reported on two components for a gas chromatograph-on-a-chip, namely an injector and a dc plasma emission detector. The injector uses two intersecting channels on a chip for injection. This geometry is commonly used in on-chip capillary electrophoresis, and is here for the first time applied for gas injection. Off-chip valves are employed to direct gas flows. Successful injection of a plug of air in helium is demonstrated by off-chip detection with a dc micro-plasma detector. The work on the dc plasma emission detector was aimed at general characterization of dc micro-plasmas and the detection of halogen atoms. Detection of bromine and chlorine is demonstrated from their atomic lines. A micro-plasma chip is coupled to a conventional gas chromatograph and specific detection of elements and molecular fragments in the eluted peaks is demonstrated. The detection limit for chlorine is shown to be about 8.10(-10) g Cl s(-1).