Reduzierter Kalibrierungsaufwand in der Gas-Chromatographie durch Einsatz eines elementselektiven Plasma-Emissions-Detektors.

A novel element-selective GC-detector, developed by us and produced in the meantime by Dr. Seitner Company (D-8031 Seefeld) is described and tested with respect to its application in routine GC analysis. The $$\underline {\text{P}} {\text{lasma - }}\underline {\text{E}} {\text{mission - }}\underline {\text{D}} {\text{etector}}$$ (PED) is based on a microwave-induced helium plasma sustained under atmospheric pressure. The plasma emission light is not analyzed with the aid of a sophisticated mono- or polychromator, needing optical adjustments, as hitherto usual. Instead a novel, simpler, filter-modulated integrated fiber optical system is used. The compact and rugged optical construction allows the simultaneous measurement of up to three elements. This paper deals with an instrumental prototype with channels for: carbon, chlorine, bromine or sulfur by comparing it to several monochromator set ups and by analyzing environmental substance mixtures (e.g., PCB with or without plastizisers). The extremely simple to handle PED shows sensitivities like the FID, linearities over three orders of magnitude, nearly absolute specifity and as the main advantage: detection independent of the molecular structure. The latter property simplifies drastically any calibration, since only one single internal or external standard is necessary for the quantification of all separated chromatographic peaks. With substances, which are measured on several channels, one quantitative result is obtained per element-channel. This allows the calculation of the mean already from one single chromatogram. The latter allows the immediate control of the separation conditions and the quality of the analytical result. Furthermore, unknown chromatographic peaks can be quantified and characterized by their molecular formulae. [ABSTRACT FROM AUTHOR]