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Objective To develop a method for the determination and impurity analysis of vitamin D3 soft capsules with soybean oil matrix in reverse phase high performance liquid chromatography (RP-HPLC) system.Methods RP-HPLC system had Agilent Zorbax Eclipse XDB-C18 column (4.6 mm × 250 mm,5 ttm) with detection wavelength of 265 nm,column temperature of 25 ℃ and flow rate of 1 mL/min.Retention behaviors of vitamin D3 and its 3 isomers were studied by altering the mobile phase.Firstly,acetonitrile was mixed with different proportions of methanol,water and ethanol as the mobile phase to investigate the effects of these 4 mobile phase components on the retention behavior of vitamin D3 and its 3 main related substances (isomers) on a C18 column.Then,a suitable mobile phase was selected for content determination and impurity analysis according to the retention behavior study.Results The recovery was only 80.55％-84.37％ with 100％ acetonitrile as the mobile phase.The addition of ethanol in acetonitrile was found to make remarkably significant improvement.Recovery rate was achieved between 98.07 ％ and 103.23 ％ with V (acetonitrile) ∶V (ethanol) =90∶10 as the mobile phase,while improving pealk shape.The method showed good linearity [(0.52-5.2) x 10-4 t mol/L,R2＞0.999] and fine density (RSD＜2.32％) which can be used for determination.For impurities profile,it could be achieved using V (acetonitrile):V (water) =95:5 as the mobile phase which can obviate interference from soybean oil matrix.Conclusions The method established in this experiment can easily and accurately determine the content and impurity analysis of vitamin D3 soft capsules with soybean oil matrix in a RP-HPLC system.
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Micellar liquid chromatography (MLC) is one of the very important analytical techniques. It contains mobile phase added with surfactants above its critical micellar concentration and the stationary phase is modified with surfactant monomers. So, micelles alter the solubilising capability of the mobile phase which forms diverse interactions with major implications in retention and selectivity. It is an alternative to conventional reversed phase liquid chromatography. It allows direct injection of physiological fluids, analysis of pharmaceutical compounds, physiological partitioning process. MLC (micelle liquid chromatography) has proved time saving as compared to other analytical technique like HPLC and ion-pairing. Applicability of MLC is increased in the field of bioanalysis. It is used to analyze different samples of drugs in serum, urine, food etc. In this review we have focused on the various examples of use of MLC in bioanalysis. This review also contains basic information about MLC such as micellar mobile phase, stationary phase, surfactants, and fundamental studies such as retention behavior and partition coefficient.
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The retention mechanism of acid drugs such as naproxen, ibuprofen, diclofenac, phenylalanine and 2,4-dichlorophenoxy acetic acid in microemulsion liquid chromatography has been discussed.The reten tion modeling between capacity factors (k') of acid drugs in microemulsion liquid chromatography and concen tration of surfactant, cosurfactant and lipophilic organic solvent and pH value was set.The results showed the effect of change of concentration of surfactant, cosurfactant and lipophilic organic solvent and pH value on capacity factors of acid drugs in microemulsion liquid chromatography was fully consistent with the theoretical modeling.The retention modeling can better reflect the effect of composition of microemulsion solution and pH value on retention behavior of acid drugs in microemulsion liquid chromatography.