ABSTRACT
Objective:To establish a DSC method for the determination of mannityl nicotinate. Methods:Indium was used to cor-rect the instrument including temperature correction and heat flow correction. The atmosphere was nitrogen and the flow rate was 20 ml ·min-1 . The sample volume was 1-3. 5 mg with precision reached to 0. 01mg. The initial temperature was 30 ℃, raised to 120 ℃ at the rate of 10℃·min-1 , maintaining for 1 min at 120℃, and raised to 280℃ at the rate of 2. 5℃·min-1 . The results of DSC and HPLC were compared. Results:Mannityl nicotinate had a good linear relationship between the heat absorption and the amount of sam-ple within the range of 1. 05-3. 44 mg (r=0. 9990). The average recovery was 98. 86％ (RSD=1. 59％,n=9). The content of nia-cin detected by HPLC and DSC was 97. 77％ and 97. 80％, respectively, and the relative mean deviation of the two values was 0. 015％. Conclusion:The DSC method is accurate and rapid, and can be used for the determination of mannityl nicotinate like HPLC.
ABSTRACT
Objective:To develop an HPLC with gradient elution method for the determination of loteprednol etabonate and the re-lated substances in loteprednol etabonate and tobramycin compound ophthalmic suspension. Methods:HPLC with gradient elution was performed with Inertsil ph phenyl column (250 mm × 4. 6 mm, 5 μm). The mobile phase A and B was 0. 25% acetic acid solution-acetonitrile (80 ∶20) and acetonitrile, respectively. The flow rate was 2. 0 ml·min-1 and the detection wavelength was 244 nm. The column temperature was 30 ℃ and the injection volume was 20 μl. Results:The main ingredient and the related substances could be well separated. Loteprednol etabonate had a good linear relationship within the range of 0. 001-1. 02 mg·ml-1(r=0. 999 9), and the average recovery was 99. 9%(RSD=0. 9, n=9). Conclusion:The assay method is sensitive, accurate and convenient with good res-olution. It can be applied to control the quality of loteprednol etabonate and tobramycin compound ophthalmic suspension.