Topics - Separation
Separation is a loose term often confused with resolution. For two substances to be separated, two elution curves must be discernable in the overall elution envelope of the two solutes. The retention time of each or either peak may not be accurately measurable or it may not be possible to calculate the areas of either peak. Separation is said to be achieved if two peaks are merely discernable. Resolution, however, is more specific. For two substances to be resolved the distance between the peak maxima must be a defined in terms of the standard deviation of either of the peaks. It is generally accepted that, for the peak heights and the peak areas to be accurately measured, the distance between the peak maxima must be equivalent to at least four standard deviations of either peak. In practice this means that the distance between the maxima of the two peaks must be twice the width of either peak measured at 0.6065 of the peak height.