Pinning Down Tailing Peaks, Part II: Quantitative Measurement

In the world of practical chromatography, peak shapes only approach an ideal Gaussian statistical distribution. Solute band shapes are perturbed by extracolumn volumes, nonideal retention processes, and strong adsorptive interactions as they move from inlet to column to detector. The first installment in this series discussed some reasons for the appearance of distorted peak shapes in gas chromatography (GC) and presented various ways of expressing the degree of peak tailing (1). Beyond just cosmetic appearance, however, chromatographers have good reasons for concern over the effects of peak tailing: distorted peak shapes affect the measurement of peak height and area, and they degrade the resolution of adjacent solutes. The extent of these effects depends not only upon the degree of peak tailing but also on the size of peaks relative to the noise level and baseline drift, as well as in relation to each other. Significant peak tailing increases uncertainties due to noise and drift; even large isolated peaks can be misquantified when they tail. This "GC Connections" installment discusses the effects of tailing on the quantitative measurement of single peaks.