The rule that you quoted is intended to cover a full-range gradient (for example, 5–100% organic solvent) and refers to the amount of volume to reequilibrate at the initial conditions.
When the aqueous solvent (solvent a) is cleaned up in terms of an on-line precolumn, the purity of the organic solvent (solvent b) can be tested according to the chromatogram of the blank gradient.
当含水溶剂通过预柱在线净化后，根据空白梯度色谱图可测试有机溶剂的纯度。
3
The ideal model of liquid chromatography in gradient elution was solved by using the characteristic approach on the assumption of a linear solvent strength model.