GC analysis of complex sample types containing non-volatile materials normally requires extensive sample preparation and cleanup prior to injection to eliminate the interference from non-volatile components. Accumulation of nonvolatile matrix components in the inlet and at the head of the GC column can lead to generation of active sites, analyte degradation, poor quantitation due to suppressed or enhanced analyte response and deterioration of chromatographic performance.
In this study we describe direct liquid injection techniques compatible with “dirty” samples containing non-volatile components. Using a glass liner that can be removed and replaced after the injection can eliminate interference from accumulated sample matrix components. Liners are designed to accommodate larger than normal liquid injection volumes to provide improved detection limits. Furthermore, the entire process including the liner exchange can be automated.
To illustrate the utility of the technique, challenging liquid sample types such as samples prepared by the QuEChERS method for pesticide analysis and contaminated motor oils were repeatedly introduced into the GC. Chromatographic performance using the new sample introduction technique is compared to conventional injections into a hot inlet.
