Toepassingsmogelijkheden van groot-volume-injectie gaschromatografie met infraroodspectrometrische detectie

Abstract

Research has been carried out to enlarge the analyte detectability of gaschromatography with infrared spectrometric detection (GC-IR) by techniques that allow injection of large volumes of liquid samples (100 ul typical). Two techniques have been investigated; loop-type and on-column interfacing. Alkanes dissolved in various solvents have been used for optimisation. Pesticides, polyaromatic hydrocarbons and other micro-contaminants have been used to test the usefulness of the eveloped system in environmental trace analysis. The increase in analyte detectability of high boiling compounds compared to conventional 1 ul split/splitless injection is almost proportional to the injected volume for injection of 100 ul. At larger sample volumes, the increase of the relative sensitivity is partly detracted by impurities of the solvent. The performance of the on-column interface is better due to the reduced loss of volatiles and the incorporation of a detector switching module that minimizes interfering solvent condensation in the IR detection interface. The potentials of LVI-GC-IR are demonstrated by the analysis of samples of drinking and surface water spiked at levels of 0.1-1 ug/l with components that commonly occur as micro-contaminants. Analytes have been detected and identified (i) by direct injection of solutions obtained by liquid-liquid extraction and (ii) by on-line desorption of at site sampled solid phase extracted cartridges. The possibility of (LVI-)GC-IR of selective screening on the prescence of specific compound classes by means of functional group chromatograms makes the technique a valuable tool in addition to GC with mass spectrometric and atomic emission detection.