![]() ![]() A jagged cut with burrs, shards of silica, or debris can cause turbulent eddies which entrap a portion of the analyte molecules as they move in or out of the column, leading to peak tailing. The quality of the cut can be inspected with a magnifying tool. ceramic wafer, diamond-tipped pen, rotating blade cutter, etc) can prove beneficial. Proficiency at cutting columns and finding a preferred tool to do so (i.e. Ensure that the column cut is smooth (no jagged edges), that no debris created during the cut is obstructing the column inlet/outlet and that the cut is at right angles to the column wall. ![]() The quality of the column cuts at both the inlet and detector side is extremely important and even small imperfections can cause significant peak tailing issues. Identify what went wrong with the following checklist. They may also be caused by unswept volumes within the system. However, when all peaks within the chromatogram show tailing behaviour it’s most often due to a physical effect, that is, if the GC was set up incorrectly! Tailing peaks are usually created through turbulence within the hydraulic path of the carrier gas as it passes through the system. Sometimes peak tailing can be caused by chemical interactions between certain analytes (usually more polar) and surfaces within the GC system. Figure 1 shows a separation in which all of the analytes within the chromatogram show peak tailing to a greater or lesser degree.įigure 1: Capillary GC chromatogram in which all analytes and the injection solvent peak show tailing to a greater or lesser degree The situation in which all peaks within the chromatogram show tailing is probably both the most common and the easiest to diagnose. How might the issues be identified and remediated?Īll peaks tail including the solvent peak The severity of the tailing will uncover further clues regarding the nature of the problem. In each of these cases, it is likely that the severity of the peak tailing will range from almost non-discernible tailing (visible only when zoomed in on the base of the peak using the chromatographic data system (CDS)) to severe tailing, which can be so bad that the analyte is barely distinguishable from the baseline. This list has been arranged in order of frequency. Ascertain if ġ) All peaks tail including the solvent peakģ) Only the solvent peak (and sometimes very early eluting analytes) show tailing The first stage in diagnosing peak tailing is to assess the nature of the tailing peaks. In this first of a series on GC diagnostic and troubleshooting, discover how best to identify the source of the issue, and find suggestions on how to prevent or fix the underlying problems. It can cause issues with resolution and peak integration, affecting both qualitative and quantitative analysis. Peak tailing is a problem which is regularly encountered in capillary gas chromatography (GC). ![]()
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