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Objective To establish a method for the determination of related substances in foscarnet sodium by HPLC.Methods The chromatography separation was performed on a CAPCELL PAK C18 chromatography column(250 mm×4.6 mm,5 μm)with mobile phase of a mixture of solution[Solution A:dissolve 3.2 g of sodium sulfate decahydrate in water,add 3 mL of glacial acetic acid and 6 mL of 0.1 mol·L-1 sodium pyrophosphate,dilute with water to 1 000 mL.Solution B:dissolve 3.2 g of sodium sulfate decahydrate in water,add 6.8 g of sodium acetate and 6 mL of 0.1 mol·L-1 sodium pyrophosphate,dilute with water to 1000mL.Solution A and Solution B(70∶30)(the pH of this mixture is about 4.4).To 1 000 mL of this solution add 0.25 g of tetrahexylammonium hydrogen sulfate and 100 mL of methanol]at a flow rate of 1.0 mL·min-1.The column temperature was 35℃.The detection wavelength was 230 nm and the injection volume was 50 μL.Results Under the chromatography conditions,the peaks of foscarnet sodium,impurityⅠ,impurity Ⅱ and other individual impurities were separated effectively.The foscarnet sodium and impurity Ⅱ showed good liner relationships(r=0.999 9)in the range of 5-248 μg·mL-1 and 1.6-9.1 μg·mL-1,respectively.The limits of detection(LODs)of foscarnet sodium and impurity Ⅱ were 23 ng and 62 ng respectively.The average recovery of impurity Ⅰ was 100.8%,RSD= 2.0%(n= 6).The average recovery of impurity Ⅱ was 98.6%,RSD=2.7%(n=12).Conclusion The method is simple,sensitive and accurate.It is suitable for the determination of related substances in foscarnet sodium.
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OBJECTIVE@#To evaluate the effect of chronic nicotine on contextual fear memory in rats.@*METHODS@#Rats were subcutaneously injected saline or nicotine for 14 days continuously to induce nicotine dependence. Somatic signs of spontaneous nicotine withdrawal were assessed on day 1 and 14 after the last injection. Locomotor activity was tested 13 days after the last injection. Contextual fear conditioning task was run 14 days after the last injection, which included 3 phases: habituation, fear conditioning, and test. Percent freezing was used as an index for fear memory during the conditioning and test phases. Finally, footshock sensitivity test was conducted.@*RESULTS@#Compared with the saline group, the global withdrawal scores significantly increased in the nicotine group when the somatic signs were assessed 1 day after the nicotine injection, while there was almost no difference in the 2 groups 14 days after the last injection. In the contextual task, the nicotine group showed a significant increase in the level of freezing response during the test phase but not in the conditioning phase. There was no significant difference in the locomotor activity and footshock sensitivity between the 2 groups.@*CONCLUSION@#Chronic nicotine enhances the contextual fear memory in rats. This effect is not attributed to the change of somatic signs, locomotor activity or footshock sensitivity.