Multielement analysis of tea leaves by inductively coupled plasma optical emission spectrometry using slurry nebulisation
Multielement analysis of tea leaves by inductively coupled plasma optical emission spectrometry using slurry nebulisation
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采用浆液雾化的电感耦合等离子体发射光谱法对茶叶进行多元素分析
DOI：
10.1039/b407416e
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
B. M. Botha
中科院分区：
文献类型：
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作者：
N. Mokgalaka;R. McCrindle;B. M. Botha
为了评价浆液雾化法作为茶叶分析的替代方法，测定了不同产地的茶叶样品的金属离子含量。通过将茶浆引入电感耦合等离子体发射光谱仪 (ICP-OES) 来测定 Al、Ba、Ca、Mg、Mn 和 Zn 六种元素的浓度。使用标准水溶液或简化广义标准添加法 (GSAM) 进行校准。简化的 GSAM 是传统标准添加方法的扩展，其原理是改变样品质量和标准溶液添加量。最初，在制备浆料之前将茶研磨3小时。在研磨样品之前包括碳化程序。研磨时间缩短至仅 30 分钟。为了进行比较，茶也通过在酸中煮沸并以水溶液形式引入血浆来消化。使用浆液分析获得的结果远高于使用水性标准进行校准的消化茶获得的结果。发现茶样品的金属含量适合区分所研究的茶样品。通过分析茶叶认证标准物质来检查该方法的准确性。学生 t 检验表明，使用浆液雾化获得的值接近认证值，置信度为 95%。应用简化的 GSAM 进一步证实了浆液技术的准确性，并且使用该方法获得的值与使用水校准浆液法获得的值相当。因此，浆液法可以成功地应用于茶叶的分析，而无需预先溶解它们。这可以避免危险化学品的使用、不完全溶解和挥发性分析物的损失。
In order to evaluate the slurry nebulization method as an alternative method for the analysis of tea, the metal ion content of tea samples of different origins was determined. The concentrations of six elements, Al, Ba, Ca, Mg, Mn and Zn, were determined by introducing tea as a slurry into an inductively coupled plasma optical emission spectrometer (ICP-OES). Calibration was performed by using either aqueous standard solutions or by using the simplified generalized standard additions method (GSAM). The simplified GSAM is an expansion of the conventional standard additions method, based on the principle of varying both the sample mass and the amount of standard solution added. Initially the tea was ground for 3 h prior to slurry preparation. A carbonization procedure was included before the sample was ground. The grinding time was reduced to only 30 min. For comparison, tea was also digested by boiling in acid and being introduced into the plasma as an aqueous solution. The results obtained using slurry analysis were much higher than the results obtained from digested tea using aqueous standards for calibration. The metal content of the tea samples was found to be suitable for differentiating amongst the tea samples studied. The accuracy of the method was checked by analyzing a tea certified reference material. The Student's t-test showed that values obtained using slurry nebulization were close to the certified values at a 95% confidence level. The simplified GSAM was applied to further confirm the accuracy of the slurry technique, and the values obtained using this method were comparable with those obtained using the slurry method with aqueous calibration. The slurry method can, therefore, be successfully applied to the analysis of tea leaves without the need to pre-dissolve them. This could avoid the use of hazardous chemicals, incomplete dissolution and loss of volatile analytes.