利用比色法简便、准确和快速地测定了巴西虫草菌丝体中虫草酸的含量。结果表明，虫草酸即D-甘露醇的最大特征吸收峰在412 nm处，质量浓度在10~50 mg/L范围内线性良好，它的线性回归方程为：Y=0.0102X-0.0029，R2=0.9989；仪器精密度良好，RSD为0.35%（n=6）；样品显色后在180 min内基本没变化；平均回收率为100.30%，RSD为1.44%（n=5）；干扰试验表明在葡萄糖、鼠李糖和果糖中，只有果糖对检测结果有较大影响。通过果糖的特征吸收峰和高效液相色谱法表明，巴西虫草菌丝体中没有果糖的存在，验证了比色法测定巴西虫草菌丝体中虫草酸含量的准确性；用该方法测定的巴西虫草菌丝体中虫草酸的质量分数为8.45%，RSD为0.34%（n=6）。

A simple, accurate and rapid colorimetry method for the determination of the cordycepic acid content in fermented mycelia of cordyceps brasiliensis henn was established. The results showed that characteristic absorption peak of cordycepic acid, mannitol, was found at 412 nm. Within a linear range of 10~50 mg/L, the regression equation was: Y=0.0102X-0.0029, R2=0.9989. The precision of the instrument was satisfactory with the RSD of 0.35% (n=6). The average recovery and RSD (n=5) were 100.30% and 1.44%, respectively. Among the tested sugar, D-fructose showed high effect on the test results. No D-fructose was found in fermented mycelia of cordyceps brasiliensis, which proved the colorimetric method was suitable for the determination of cordvcepic acid content in fermented mycelia of cordyceps brasiliensis henn. The mannitol content in fermented mycelia of brasiliensis was found to be 8.45% with the RSD value of 0.34%.

农业结构调整重大技术研究专项(06-08-03B)；广东省科技攻关项目(2005B20401020)