应用标准添加法测定黄酮类物质在桑叶中的总量

[目的]研究桑叶中黄酮类物质的测定方法并优化测定条件。[方法]以水为提取剂,沸水浴5 min提取桑叶中的黄酮类物质。利用NaNO2-Al(NO3)3-NaOH光度法测定桑叶中的黄酮类物质总量,并将标准添加法应用于测定操作中以优化测定条件。[结果]单因素试验表明,60%乙醇补加量为0~11 ml,NaNO2用量为0.50~2.00 ml,Al(NO3)3用量为0.75~2.00 ml及NaOH用量为1.50~5.00 ml时,有色溶液的吸收值差异均不大,提取时间引起的有色溶液的吸收值差异也不大。但Al(NO3)3过量太多,则有色溶液的稳定性差。NaOH用量少于3.00 ml时,显色反应比较慢。[结论]利用标准添加法测定桑叶中的黄酮类物质可避免由于待测样品溶液用量过多而无法正常测定的情况。用1∶100的样水比,沸水浴5 min的浸提方法可提取出磨碎桑叶中的绝大部分黄酮类物质。

Application of Standard Addition Method in the Spectrophotometric Determination of Flavonoids in Mulberry Leaves

[Objective] The aim was to study the determination methods of flavonoids in mulberry leaves and optimize the determination condition.[Method] With water as extractant,the flavonoids were extracted in boiling bath for 5 min.The total quantity of flavonoids in mulberry leaves was determined by NaNO2-Al(NO3)3-NaOH spectrophotometry and the standard addition method was applied into the determination operation to optimize the determination condition.[Result] The single factor experiments showed that when the addition of 60% ethanol was 0～11 ml,the dose of NaNO2 was 0.50～2.00 ml,the dose of Al(NO3)3 was 0.75～2.00 ml or the dose of NaOH was 1.50～5.00 ml,the differences on absorption value among colored solutions were little and that induced by extraction time was little,too.But when Al(NO3)3 was too much excessive,the stability of colored solution became worse.When the dose of NaOH was less than 3.00 ml,the coloring reaction was slower.[Conclusion] Determination of flavonoids in mulberry leaves by standard addition method could avoid the circumstance that the flavonoids couldn't be determined normally due to too much consumption of tested sample solution.The method of extraction with ratio of sample to water being 1∶100 and in boiling bath for 5 min could extract the most flavonoids from the grinded mulberry leaves.