铬天青S-铝抑制褪色光度法测定茶叶中痕量氟

Determination of Trace Fluorine in Tea by Decoloration Spectrometry of Chrome Azurol S-Aluminium

研究了在pH=5.5的六次甲基四胺缓冲液介质中,氟离子对铬天青S(CAS)与铝离子的络合的阻抑作用,由此建立了测定痕量氟的褪色光度法。以545nm为测定波长,在有最佳测定条件下,其校准线性方程为ΔlgA=-0.01784+2.5142C,相关系数为r=0.99938,此方法测定的线性范围为0.01—0.6μg·mL-1,检出限为1.1×10-2μg·mL-1。用该法测定了茶叶中含的痕量氟,分析结果令人满意。

A method for determination of trace amount fluorine in tea was developed based on the inhibition of the fluorine ion to the coordination of Al^3＋ with chrome azurol S（CAS） in a medium of hexamethylene tetramine buffer solution at 545nm. Under optimum determination conditions the standard linear equation is △lgaA=1 0. 01784 ＋2. 5142C, r= 0. 99938. The linear rang is 0. 01- 0. 6μg · mL^-1 with a detection limit of 1.1× 10^-2μg · mL^-1. The method was used to determine the trace fluorine in the tea with satisfactory results.