General retention time formulae for gradient liquid chromatography with any combination of isocratic, linear and stepwise gradients
梯度液相色谱中任意等度、线性和阶梯梯度组合下的保留时间公式

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. By considering the influence of the dwelling time of the chromatographic system on retention time, the retention time formulae suited for any combination of isocratic, linear and stepwise gradients were obtained. It was found that the values of the retention time obtained from these formulae were in well accordance with those computed by using the finite-difference method, which confirms the validity of the formulae. Due to the simplicity and broad scope of applications, these formulae can be easily applied in practice.