Ability of a column to separate chromatographic peaks; R_s ≡ (t_R2 – t_R1)/[(w_b1 + w_b2)/2], where t_R2 and t_R1 are the retention times of the two peaks and w_b is the baseline width of the peaks. It usually is expressed in terms of the separation of two peaks. A value of 1 is considered to be the minimum for a measurable separation to occur and to allow good quantitation. A value of 0.6 is required to discern a valley between two equal-height peaks. A value of 1.5 is considered sufficient for baseline resolution for two peaks of equal height. Values of 1.7 or greater generally are desirable for rugged methods.