Impact of methanol and acetonitrile on separations based on pi-pi interactions with a reversed-phase phenyl column.
Studies were performed to investigate the roles of methanol and acetonitrile on the retention mechanism of an active pharmaceutical ingredient (API) and related compounds with a reversed phase phenyl column. Different retention orders were observed depending upon whether acetonitrile or methanol was used as the organic modifier. We propose that acetonitrile impedes the selective pi-pi interactions between the analyte molecules and the phenyl groups in the stationary phase. Further study with 1-naphthoic acid and 1-naphthol as test compounds in the HPLC separation provides additional support for the influence of acetonitrile on pi-pi interactions between analyte molecules and a phenyl stationary phase. This study suggests that methanol be used as the preferred organic modifier with phenyl columns to achieve selectivity based upon pi-pi interactions.
Yang
Min
M
Novartis Pharmaceuticals, Chemical and Analytical Development, 436-2217, 1 Health Plaza, East Hanover, NJ 07936, USA. min.yang@pharma.novartis.com
Fazio
Steven
S
Munch
David
D
Drumm
Patrick
P
D000097:Acetonitriles / Q000737:chemistry*; D000327:Adsorption; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation* / Q000379:methods; D006860:Hydrogen Bonding; D000432:Methanol / Q000737:chemistry*; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results
D000097:Acetonitriles; D004364:Pharmaceutical Preparations; D000432:Methanol; C032159:acetonitrile