"Orthogonal" separations for reversed-phase liquid chromatography.
A general procedure is proposed for the rapid development of a reversed-phase liquid chromatographic (RP-LC) separation that is "orthogonal" to a pre-existing ("primary") method for the RP-LC separation of a given sample. The procedure involves a change of the mobile-phase organic solvent (B-solvent), the replacement of the primary column by one of very different selectivity, and (only if necessary) a change in mobile phase pH or the use of a third column. Following the selection of the "orthogonal" B-solvent, column and mobile phase pH, further optimization of peak spacing and resolution can be achieved by varying separation temperature and either isocratic %B or gradient time. The relative "orthogonality" of the primary and "orthogonal" RP-LC methods is then evaluated from plots of retention for one method versus the other. The present procedure was used to develop "orthogonal" methods for nine routine RP-LC methods from six pharmaceutical analysis laboratories. The relative success of this approach can be judged from the results reported here.
Pellett
Jackson
J
Pfizer Global Research & Development, Pharmaceutical Sciences, Analytical R&D, Michigan Laboratories, Ann Arbor, MI, USA.
Lukulay
Patrick
P
Mao
Yun
Y
Bowen
William
W
Reed
Robert
R
Ma
M
M
Munger
R C
RC
Dolan
J W
JW
Wrisley
Loren
L
Medwid
K
K
Toltl
N P
NP
Chan
C C
CC
Skibic
M
M
Biswas
Kallol
K
Wells
Kevin A
KA
Snyder
L R
LR
D002853:Chromatography, Liquid / Q000379:methods*; D003198:Computer Simulation; D004340:Drug Contamination; D008433:Mathematics; D004364:Pharmaceutical Preparations / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry
D004364:Pharmaceutical Preparations; D012997:Solvents