Study On Retention Mechanism And Application In Micellar Liquid Chromatography

Micellar liquid chromatigraphy (MLC) is a reversed phase liquid chromatography (RPLC) with mobile phases containing surfactant above its critical micellar concentration (cmc). The retention of solutes was depended on the assembled interaction of solutes with the micelles in the mobile phase and with the modified stationary phase. The retention characteristics of solutes were influenced by the surfactant concentration, pH, organic modifier and so on. This topic is aimed to study the retention behavior of the hypnotic drugs in the MLC and application of MLC in the pharmaceutical analysis.The experimental results showed the hypnotic drugs investigated are the union solute in the SDS micellar system. When mobile phase pH value different, the existence forms of solutes change in SDS micellar system so that their chromatograph retention value changes. With the increase of the surfactant concentration, the organic modifier proportion or the branched chain of organic modifier as well as the column temperature , the retention values of the union solutes on the chromatographic column reduce. The capacity factor of hypnotic drugs was plotted against surfactant concentration and the organic modifier proportion to obtain a better linear cure for a given set of chromatographic conditions. In conclusion, the effect of various factors on rentention bahavior of the hypnotic drugs in MLC had been studied so that to provide theoretical foundation for its application.A micellar liquid chromatography method for the determination of naproxen and ibuprofen in pharmaceuticals and urine sample was firstly established using nonionic surfactant Tween-80 as mobile phase and without any organic modifier. The experimental results showed the calibration curve was better linear (r=0.9996) in the range of 0.1～1.1 mg·ml^-1 for naproxen content under the selected chromatographic conditions. The limit of detection (LOD) for naproxen was found to be 0.05 ng·s^-1(3S/N). The recovery of the method for naproxen was 99.6～100.6%. And, the linearity was better in the range 0.2～1.0 mg·mL^-1(r=0.9994) for ibuprofen. The limit of detection (LOD) for ibuprofen was found to be 3.0ng·s^-1(3S/N). The recovery of the method for ibuprofen is 100%～101.0%. For the analysis of ibuprofen in the urine samples, one great advantages of the method is that no extraction step is required. It is a simple, fsat and accurate method for the determination of naproxen and ibuprofen. It is a environmentally benign method because of not using any toxic organic solvents. A new method for deterimination of naproxen and ibuprofen content was provided.The correlative analysis between the capacity factors of acidic compounds in the micellar liquid chromatography and their the octanol-water partition coefficient (logP) had been studied. The effect of the kind and concentration of surfactant and pH value in the mobile phase on the relationship between the capacity factors of acidic compounds and their logP was investigated. The experimental results showed there is better relationship between the capacity factors of acidic compounds in MLC using containing Tween-20 surfactants solution (pH=3.0) as mobile phase and their logP. The established modeling has good stability and accuracy for prediction of the octanol-water partition coefficient (logP) of acidic compounds, which can provide valuable reference information for hydrophobicity of acidic compounds.