Application Study Of ZIC-RP-HILIC Mixed-Mode Column In Antibiotics & Degradation Impurity Study Of Ceftriaxone

This thesis study the application and mechanism of zwitter ion exchange‐reversedphase‐hydrophilic interaction (ZIC‐RP‐HILIC) mixed‐mode column; Using ZIC‐RP‐HILICmixed‐mode liquid chromatography‐Mass Spectrometry technology to identify impurities ofceftriaxone of the third generation cephalosporin antibiotics and determine the stability andanalytical method of ceftriaxone in order to establish a more scientific and complete qualitycontrol(QC) method.ⅠApplication and mechanism study of zwitter ion exchange‐reversed phase‐hydrophilicinteraction (ZIC‐RP‐HILIC) mixed‐mode columnObjective: 1.To establish a quantitative analysis method to simultaneous determine positive andnegative pharmaceutical counter ions using ZIC‐RP‐HILIC mixed‐mode chromatography coupledwith ELSD in order to make up the defect of the pharmacopoeial QC method of pharmaceuticalcounter ions;2. To establish a qualitative analysis method to identify related substances of polarcompound instead of reversed phase ion‐pair chromatography. Developing new structureidentification and peaks matching method at different chromatographic system to identifyantibiotic impurities.3.Using salvation equation and liner‐free‐energy equation, giving out thebest correlation structure parameters between column parameters and structure parameters ofanalyzing antibiotics, with the result to predict the retention behavior of other compound andstudy mechanism of this mixed‐mode column.Method: 1. Simultaneous determination of positive and negative pharmaceutical counter ionsusing ZIC‐RP‐HILIC mixed‐mode chromatography coupled with ELSD and ammonium acetatebuffer salts. Two commonly used pharmaceutical ions (hydrochloride and sodium salt) werestudied and five kind of antibiotics and their counter ions were adopted for validation ofanalytical method.2. Separation and identification of impurities in antibiotics by a combinationof reversed phase liquid chromatography, column switching and zwitter ion exchange‐ reversedphase‐hydrophilic interaction liquid chromatography (ZIC‐RP‐HILIC)‐mass spectrometry. Thismethod has been demonstrated efficient in the analysis of Penicillin V Potassium, Oxacillin,Ceftriaxone and their impurities.3.Using Discover studio software to predict structure parameters of analyzing antibiotics and set up liner‐free‐energy equation to find out the bestcorrelation structure parameters, with the result to predict the retention behavior of othercompound and study mechanism of this mixed‐mode column.Results: 1.The HPLC method to determine pharmaceutical counter ions is an accurate andconvenient method. 2. The antibiotic impurities eluted in the ion‐pair reversed phasechromatography were directly characterized by ZIC‐RP‐HILIC‐MS system using column‐switchingtechnique and two‐dimensional chromatographic correlation analysis, the method was found tobe convenient and usable for qualitative analysis of antibiotic, which could be applicable toother pharmaceutical impurity analysis.3. The liner‐free‐energy equation can predict theretention behavior of other compound accurately.Conclusion: This column provides ion exchange property when analyzing the counter ions. Itprovides ion exchange/ reversed phase property at low percentage of organic solvent and HILICbehavior at high percentage of organic solvent when analyzing the pharmaceutical mainconstituent. It has advantage in analyzing the counter ions and polar compound. Theliner‐free‐energy equation can predict the retention behavior of other compound accuratelyand it is a good method to represent the character of column.ⅡDegradation kinetics and impurity study of ceftriaxone.Objective: The analyzing method of ceftriaxone is reversed phase ion‐pair chromatographywhich is complicated and incompatible with LC‐MS system as its strong polar character.Combination the mechanism of ZIC‐RP‐HILIC mixed‐mode, degradation kinetics and impuritystudy of ceftriaxone is inspected; A new structure in chromatography of ceftriaxone has beenstudied in order to establish a more scientific and complete quality control(QC) method.Method: This study use ceftriaxone as example, performing accelerated stability test. Thefactors of buffer ion, ionic strength, pH, degradation temperature have been investigated toinspect the influence for degradation rate. Identifying ceftriaxone impurities withZIC‐RP‐HILIC‐MS and a new impurity and two configuration of ceftriaxone have been found. Thistwo configuration can interconvert when condition change. Structure identification of theisomer was studied by NMR and find out the reason of the isomer produced. Results: ceftriaxone hydrolyses in the position of 3‐ substituted C‐S bond in the catalysis oforganic acids (formic acid,acetic acid),and there are some ionized state at different pH.So theyhave different retention time in chromatogram. So it is important to control analysis conditionto ensure the compound is in one kind of ionized state.Conclusion: Degradation of ceftriaxone in organic acids is a specific phenomenon or a commonphenomenon, this problem will be study. Reversed phase ion‐pair chromatography iscommonly used in QC, but it is easily influenced by analysis condition. So it is important tocontrol the analytical condition strictly.