温度对钼蓝比色法测定植物样品中硅的影响

钼蓝比色法是常用的测硅方法,但其测定结果受温度影响很大。本试验以硅的标准植物样—灌木枝叶为试材,样品在瓷坩埚中灰化后,用氢氟酸浸提,采用钼蓝比色法在811nm波长下测定硅的含量。显色温度设为15℃、25℃、30℃、35℃,显色时间分别为10min、20min、40min、60min和120min,研究不同温度和显色时间对硅测定结果的影响。结果表明,温度显著影响显色反应的速度,15℃显色20min时,测定值才接近标准值,高于15℃显色时间加快,显色10min测定值即达到标准值。温度同样影响显色稳定时间,在30℃和35℃放置40min时测定值已显著低于标准值,相反在15℃和25℃时,即使保持2小时对硅的测定仍没影响,且测定结果准确性较高。结果表明在本实验条件下,可以在25℃下进行大批量植物样品的测定。

The Influence of Temperature on Silicon Colorimetric Determination in Plant Material

Colorimetric determination method was common for the detection of silicon in plants, but the accuracy of this method was often affected by incubation temperature and coloring period.Leaves of willow, the standard substance of silicon determination, were dry-ashed in porcelain crucibles before digestion with HF. After suitable dilution, Si was determined colorimetrically at different temperature such as 15℃,25℃,30℃, and 35℃,held for 10min, 20min, 40min, 60min and 120min. Coloring time consumption and coloring speed was affected by temperature. Coloring time consumption was higher in 15℃ than the other temperatures,but the color stability was different. The result at 30℃ and 35℃ was on the contrary. The determination accuracy at 25℃ was much better than the others. This means that 25℃ is an ideal temperature in silicon determination.