The Study On Application Of Microemulsion Liquid Chromatography In Pharmaceutical Analysis

Microemulsions are consisted of nanometre-sized droplets which contain two kinds of immiscible liquid. Droplet formation is facilitated by the addition of surfactants and also cosurfactants. Microemulsions are classified as two types:oil-in-water (O/W) and water-in-oil (W/O). Both microemulsion types have been used as mobile phases for separation in microemulsion HPLC (MELC). Comparing with conventional HPLC, MELC has superior speed, efficiency, a unique selectivity in separation. Microemulsion is a kind of micellar solution modified by lipophilic organic solvent. The retention of solutes in MELC mainly depends on the balance reactions between the aqueous phase, modified micellar phase and stationary phase.The MELC was successfully applied for analysis of the content of pravastatin sodium, atorvastatin calcium, lovastatin and simvastatin in tablets. The experimental results showed that isogradic microemulsion liquid chromatography posses better ability in rapid separation of statins mixture which has very different hydrophobicity. The effect of change of concentration of surfactant, cosurfactant and lipophilic organic solvent on retention behavior of statins in microemulsion liquid chromatography was fully consistent with the theoretical modeling. The effect of pH value of mobile phase on retention behaviors of acid statins was fully consistent with the theoretical modeling. The relationship between capacity factors of neutra statins and concentration of hydrogen ion was implicit function. It is a simple, fast, accurate and precise method for the determination of pravastatin sodium, atorvastatin calcium, lovastatin and simvastatin.Microemulsion liquid chromatography was used for determination of retinol acetate and vitamin E in capsules. The chromatographic conditions such as the concentration of co-surfactant, surfactant and lipophilic phase as well as the pH of the mobile phase were optimized. The optimal mobile phase was obtained with a microemulsion containing 1.5%w/w of isooctane,4% w/w of sodium dodecyl sulphate (SDS),8% w/w of n-buthanol and 25mmol/l potassium dihydrogen phosphate, and the pH was no need to adjust. The established method was validated and applied in analysis of appropriate pills. The proposed chromatographic procedure for the determination of retinol acetate and vitamin E is less expensive compared with the conventional reversed-phase HPLC method, as well as simple and reliable.In addition, the effect of concentration of surfactant, cosurfactant and lipophilic organic solvent, the column temprature and pH value on separation efficiencies of oxytetracycline, chloroteracycline and progesterone in cosmetics had been investigated. The better chromatographic conditions were selected, Which the microemulsion solution containing 2.5% SDS,6.5% n-propanol,0.8% ethyl acetate and 25 mmol/L potassium dihydrogen phosphate (pH=5.2) used as mobile phase. The experimental results showed that isogradic microemulsion liquid chromatography posses better ability in rapid separation of two antibiotics and progesterone in cosmetics simultaneously, so the method can be used for assuring if the content of the three drugs in cosmetics exceeded the standards.