The Effect of Ion Pairing Reagents in the Retention Profile of Zwitterionic Cephalosporins

The retention of three zwitterionic cephalosporins, Cefepime, Cefpirome, and Ceftazidime, in a broad pH range was studied by means of reversed phase high performance liquid chromatography (RP-HPLC) and reversed phase ion-pair liquid chromatography (RP-IPC), using an octadecylsilane stationary phase...

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Bibliographic Details
Published inJournal of liquid chromatography & related technologies Vol. 26; no. 6; pp. 937 - 952
Main Authors Pistos, C. M., Tsantili-Kakoulidou, A., Koupparis, M.
Format Journal Article
LanguageEnglish
Published Colchester Taylor & Francis Group 01.04.2003
Taylor & Francis
Subjects
Analysis
Biological and medical sciences
Cefepime
Cefpirome
Ceftazidime
General pharmacology
High performance liquid chromatography
Ion-pair liquid chromatography
Medical sciences
Pharmacology. Drug treatments
Zwitterions
Chemical analysis
Phase composition
Cefepime
Cefpirome
Chromatographic retention
Lactam
Ion pair
HPLC chromatography
Zwitterion
Mobile phase
Antibiotic
Reversed phase chromatography
Cephalosporin derivatives
pH
Qualitative analysis
Antibacterial agent
Ceftazidime
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Summary:The retention of three zwitterionic cephalosporins, Cefepime, Cefpirome, and Ceftazidime, in a broad pH range was studied by means of reversed phase high performance liquid chromatography (RP-HPLC) and reversed phase ion-pair liquid chromatography (RP-IPC), using an octadecylsilane stationary phase and acetonitrile as organic modifier. Sodium hexane-, heptane-, and octane-sulphonate and tetrabutylammonium hydroxide were used as sources of counter ions in ion pair chromatography. The presence of the permanently charged quaternary nitrogen in the cephalosporin molecules leads to zwitterionic species over a broad pH range, masking the carboxylic acid function and stabilizing the retention. The effect of the counter ion depends on the ionization state of the compounds. Formation of ion pairs with the opposite charged center of the molecules led to significant increase in retention. At pH values favoring the zwitterionic species a decrease in retention was observed as a result of the disruption of the intramolecular interactions and the deliberation of the free charge. The extent of ion pair formation and the competition with the zwitterionic species, depended on the counter ion concentration in the mobile phase and was reflected in retention. The effect of the size of the counter anion alkyl chain on retention was investigated at different pH as well.
ISSN:1082-6076
1520-572X
DOI:10.1081/JLC-120018894