There was a case in which the column efficiency was reduced and a peak tailing occurred (see chromatogram A) after a conventional column (150 X 4.6mm I.D.) had been replaced with a short column (75 X 4.6mm I.D.) to reduce the analysis time. Although this problem was corrected by replacing the injector, the cause remained unclear. The main difference between before and after the replacement of the injector was the amount of sample dispersion before the column. The shorter the retention time, the more a peak shape becomes adversely affected by pre-column dispersion.
As a result, dispersion of the sample had a greater influence on the peak shape with the short column than it had with the conventional column, resulting in deterioration of the peak shape.

Although it is often thought that problems of peak inferior shape are due to a deficiency of column performance or  a defective column, some cases are caused by hardware problems introducing too much dead volume into the system. The impact of extracolumn dispersion is often overlooked when using a short column. Even with the short column, the tubing length and internal diameter, the injector type, etc should lead to minimal extracolumn dispersion.