Single Pump On Line Addition of Modifier for Supercritical Fluid Chromatography
超临界流体色谱系统中采用单泵在线添加改性剂

Modified CO 2 as mobile phase is usually necessary for packed column supercritical fluid chromatography. Single syringe pump was applied in this work to add modifier through a parallel connection device, which can maintain constant and stable volume fraction of modifier without any contamination of the pump. Viscosity of the modifiers (here are methanol and acetone)and the length of the CO 2 pipe line/modifier pipe line can affect the volume fraction. Volume fractions of methanol and acetone were determined by gas chromatography and ultraviolet spectrometry respectively and their rules of variation were also examined. It shows that the volume fraction of methanol is lower than that of acetone under similar condition. With fixed modifierr line, the longer the CO 2 line is, the higher the volume fraction will be. The new device can conveniently alter the nature and ratio of the modifier with quite stable volume fraction. The online addition device can tentatively replace the dual pump system.