铬天青S分光光度法测定砖茶铝的方法学探讨

Aluminum content determination in brick-tea with chrome azurol S spectrophotometric method

目的寻找一种经济实用并较准确的砖茶铝测定方法。方法用HNO3、HClO4将砖茶消解成无色溶液,调解pH值至3左右;去离子水稀释250倍,用铬天青S分光光度法在波长为620 nm处比色测定砖茶含铝量。结果加标平均回收率为102．4％,平均变异系数(CV)为2．82％,对国家茶叶标准物中含铝量测定与给定值的相对偏差为-5．74％。结论铬天青S分光光度法测定砖茶含铝量结果准确可靠,可以用于砖茶样品含铝量的检测。

Objective To study a method for determining aluminum in brick-tea. Methods Brick-tea was digested into transparent solution using HNO3, HClO4. pH value was adjusted to around 3, and the prepared solution was diluted 250 times. The brick-tea aluminum content was detected with chrome azurol S spectrophotometric method in 620 nm wave length. Results The average rate of recovery was 102.4%, the coefficient of variations （CV） was 2.82%. The aluminum content in national tea referential material was detected and the relative deviation with the standard value was - 5.74%. Conclusions The results of aluminum content in brick-tea determined with this method is accurate and reliable. The method can be used for determining aluminum in brick-tea.