Temperature and Pressure Behaviours of Methanol, Acetonitrile/Water Mixtures on Chromatographic Systems

Temperature and pressure were shown to vary significantly with solvent mixing, showing maxima at different solvent ratios. Acetonitrile/water mixing resulted in temperature reduction of solutions whereas methanol/water mixing caused temperature increases. On the other hand, maximum recorded chromatographic pressure of acetonitrile:water mixtures occurred at a solvent ratio of 1:6 compared with methanol:water, which showed a maximum pressure at a solvent ratio of 1:1. These findings can be of use in stabilizing retention time shifts during HPLC-based studies associated with compound identification based on retention time such as analysis of complex mixtures.