浅谈水分对DSC法熔点分析的影响

Brief discussion on the influence of moisture on DSC melting point analysis

关键词:  差示扫描量热法  熔点分析  水分影响  方法优化

Key words:  differential scanning calorimetry(DSC)  melting point analysis  influence of moisture  method optimization

摘要:

目的 研究DSC法熔点分析中吸附水分的影响。方法 常规DSC法熔点分析起始温度为室温30℃,升温速率为10℃.min_-1^,气氛为氮气,干燥气为50 ml.min_-1^；优化后DSC法熔点分析起始温度为熔融温度前20℃,升温速率为1℃.min_-1^,其余参数不变。结果 无需干燥处理试样,常规DSC法熔点分析可以准确检测水分含量分别为4.3%、5.3%和6.1%的咪唑、盐酸去氧肾上腺素和甲硫新斯的明试样,优化DSC法熔点分析可以准确检测咪唑、盐酸去氧肾上腺素和甲硫新斯的明试样的水分含量可以达到9.0%、6.0%和7.1%。结论 无需干燥处理试样,常规DSC法熔点分析一般可以准确检测水分含量不超过4%的试样,优化方法可以进一步排除更高含水量(小于6%)对熔点分析的影响。

Abstract:

OBJECTIVE To study on the influence of moisture on DSC melting point analysis. METHODS In the general method of DSC melting point analysis, the melting range with 30 ℃ of start temperature and 10 ℃?min-1 heating rate, the atmosphere was nitrogen and the dry gas flow was 50 ml?min-1. In the optimization method, the start temperature was 20 ℃ before melting temperature, the heating rate was adjusted to 1 ℃?min-1, and the other parameters remained unchanged. RESULTS Without drying test samples, the melting point could be detected accurately in the general method of DSC melting point analysis for the imidazole, norepinephrine hydrochloride and methylthioneostigmine samples with moisture content of 4.3%, 5.3% and 6.1% respectively, and in the optimization method, it could be analyzed exactly for the homologous samples with moisture content of 9.0%, 6.0% and 7.1% respectively. CONCLUSION The test samples did not need to be dried in the DSC melting point analysis. It might be analyzed accurately for test samples with moisture content not exceeding 4% in the general method of DSC melting point analysis, and in the optimization method, the influence of higher moisture content (less than 6%) might be eliminated.