Flow inconsistency: the evil twin of column switching--hardware aspects.
Solvent flow, generated by HPLC pumps is consistent and accurate. This statement, while true for single column (one dimensional) liquid chromatography applications, may not apply to column switching applications. Connection of pumps and/or columns to one flow path may cause substantial pressure changes. Immediate post valve switch pressure differences between pumps can cause backflow where the mobile phase stored at higher pressure will temporary flow into the lower pressure area. A more common side effect of column switching is flow inconsistency during pump pressurization. For the duration of pump pressurization, liquid flow through the column will be smaller than expected since the HPLC column acts like a flow restrictor.
Rogatsky
Eduard
E
Analytical Core Lab, Institute for Clinical and Translational Research, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Ave., Bronx, NY 10461, USA. eduard.rogatsky@einstein.yu.edu
Braaten
Kara
K
Cruikshank
Greg
G
Jayatillake
Harsha
H
Zheng
BingNa
B
Stein
Daniel T
DT
D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D004867:Equipment Design; D011312:Pressure