Application Of Mixed-mode Chromatography In Separation Of Basic Dyes And Acidic Antibiotics

HPLC is a method has been widely used in many fields because of its advantages of simple operation and fast analysis. However, the single mechanism of conventional chromatography has some limitations on the selectivity of complex samples. Mixed-mode chromatography(MMC) is a kind of material bonding with multifunctional groups, which can improve selectivity of samples greatly. In this paper, on the basic of mixed-mode materials researched by our team, to develop new methods for the separation and analysis in the fields of food and medicine.On the general reversed-phase stationary phase, the selectivity always poor with poor reproducibility or tailing in the basic compounds separation. As has been reported, XCharge C18materials can demonstrate the good selectivity for basic compounds separation. This paper is to take it as stationary phase, to develop a QuEChERS-HPLC methods for the fast determination of malachite green(MG), crystal violet(CV) and their metabolites of leucomalachite green(LMG) and leucocrystal violet(LCV) residues in fish tissue. After optimization and validation, the results show that the method is feasible, and the absorbent materials of reversed-phase liquid chromatography/strong anion exchange(RPLC/SAX) can remove impurities effectively and improve the recoveries of four dyes significantly. The recoveries were in the range of88.63%-11.62%, the RSD%were in the range of0.7%-3.5%.Due to the characteristics of similar structure, the selectivity of β-lactam antibiotics on conventional reversed phase column is poor. Given the nature of the charged sample, in this thesis, reversed-phase liquid chromatography/weak cation exchange(RPLC/WCX, C18/WCX) is adopted for development of β-lactam antibiotics separation method. The results show that the samples and impurities has high selectivity with C18/WCX. It is found that the mechanism of samples separated on C18/WCX are hydrophobic interaction and ion exchange interaction.The results show that using MMC on separation of charged compounds has high selectivity. The molecular level aggregation mixed-mode chromatographic materials have more advantages than macroscopic particles mixed-mode. RPLC/IEX materials can obtain good tenability with charged samples on selectivity.