Application of an atmospheric pressure helium microwave-induced plasma as an element-selective detector for gas chromatography

An atmospheric pressure helium microwave-induced plasma (MIP) was combined with a gas chromatograph (GC). and used as an element-selective detector for GC. The detection limits, dynamic ranges and selectivities were obtained for H, C, F, Cl, Br, I and S. Such data for nitrogen and oxygen could not be obtained because of the interference from air which was entrained into the system through the leakages of the tubing and the valve system. The detection limits and dynamic ranges for all the elements investigated were in a range between 1.8 and 39pgs^?1 and between 1.6 × 10³ and 1.1 × 10⁵, respectively. Furthermore, the relative sensitivities of C, H, Cl and Br for various compounds were examined. In the cases of carbon and hydrogen, the relative sensitivities were not the same for different compounds containing oxygen and nitrogen. This result may be explained by the incomplete decomposition of such compounds due to the low microwave power (75 W) applied in the present system.