EA-MS测试过程中添加助燃剂的影响效应研究

The Effect of Oxidizer Appended During Testing Sample by EA-MS

利用元素分析-质谱仪(EA-MS)联用系统,探讨对高C/N植物样品测试过程中添加助燃剂对样品氮同位素比值、氮含量和仪器本底的影响。在植物样品中添加CuO或者V2O5,测定的氮同位素组成结果表明:添加助燃剂导致样品测试的结果偏差更小,这与测试过程中植物样品能够完全燃烧有关;添加助燃剂使测试的氮含量高于不添加助燃剂的情况,同时仪器本底也能迅速降低,说明助燃剂的添加有助于样品在瞬间燃烧,因此使测试结果更为精确;不同助燃剂的添加对植物氮同位素比值结果的影响程度不同,与不添加助燃剂的情况相比,CuO的添加使得同位素比值偏正,而V2O5的添加结果不具有规律性;在样品中添加CuO助燃剂(和植物样品以4∶1的质量比混合),样品测试的同位素值偏差最小,测试结果也更加可信,样品本底可以达到连续做样而不影响测定下一样品的氮同位素组成。该方法简单、有效、投入较少,可以用于难以反应的样品分析中。

The effects of oxidizer appended during testing high C/N ratio plant sample were studied by EA-MS. CuO and V2O5 were used to blend with plant power alone or all together during determined by EA-MS. The results showed that standard deviation was lower when oxidizer was appended, and the reason was ascribed that sample was oxidized completely. Oxidizer affected plant nitrogen content determined and instrument＇s background obviously. Higher nitrogen content was obtained and instrument＇s background fall down rapidly, which means that sample oxidized instantaneously and more correct results could be obtained. Different oxidizer appended had different effects to nitrogen stable isotopic composition. The optimal condition were CuO appended in plant sample （M（plant） ： M（oxidizer） = 4 ： 1）, in which condition credible δ^15N data could be obtained and instrument＇s background was constant during sample testing. The method is simple, effective and cheaper for determined stubborn samples.