目的: 探讨吸附水分对差示扫描量热（DSC）法测定药物纯度的影响。方法: 药物纯度DSC测定的升温速率为0.5 ℃ · min-1,气氛为氮气,干燥气为50 mL · min-1;优化后的方法起始温度较常规方法提前10 ℃,并增设速率为1 ℃ · min-1的升温程序10 min,其余参数不变。结果: 无需干燥处理试样,常规DSC法可以准确测定吸附水分小于7%的咪唑、盐酸去氧肾上腺素和甲硫酸新斯的明试样的纯度。方法:优化后进一步排除吸附水分干扰,吸附水分小于8%的上述试样均可以准确分析。结论: 吸附水分可能影响DSC法纯度分析的结果,熔融温度高于80 ℃且吸附水分小于7%的一般试样无需干燥处理,优化后的方法可进一步降低吸附水分的影响。
Objective: To investigate the effect of adsorbed moisture on drug purity determination by differential scanning calorimetry (DSC). Methods: The DSC analysis for drug purity was performed with a heating rate of 0.5 ℃ · min-1 under a nitrogen atmosphere (drying gas flow rate: 50 mL · min-1). The optimized method reduced by 10 ℃ than the conventional method and included an additional heating segment at 1 ℃ · min-1 for 10 min, while other parameters remained unchanged. Results: Without pre-drying, the conventional DSC method accurately determined the purity of imidazole, phenylephrine hydrochloride, and neostigmine methylsulfate samples with adsorbed moisture below 7%. After optimization, the method further eliminated moisture interference, allowing accurate analysis of samples with adsorbed moisture below 8%. Conclusion: Adsorbed moisture may affect DSC-based purity analysis. For general samples with a melting point above 80 ℃ and adsorbed moisture below 7%, pre-drying is unnecessary. The optimized method further reduces the impact of adsorbed moisture.
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