负热电离质谱测定硼同位素的涂样试剂比较

目前人们并未注意到利用负热电离质谱方法测定硼同位素所采用涂样试剂中BO^-的同质异位素CNO^-离子的存在和影响。对硼同位素测定采用的不同涂样试剂进行比较，结果发现在去硼海水和硝酸盐溶液中存在BO2^-的同质异位素CNO^-离子，干扰离子不仅来自有机物，而且可能来自硝酸根。在硼同位素测定中，检查空白中的43峰和43／42比值是必要的。实验表明MgCl2 NaOH混合溶液是负热电离质谱测定硼同位素的较为理想的涂样试剂。

A Comparison of Loading Reagent for Boron Isotopic Measurement by Negative Thermal Ionization Mass Spectrometry

The isobaric (CNO - ions) interference involved in the loading reagents has not been noted for boron isotopic measurement by nagetive thermal ionization mass spectrometry (NTIMS). A comparison experiment of different loading reagents was investigated. The result revealed that high isobaric interference ion (CNO -) for boron isotopic measurement was observed in the boron free seawater and the nitrate. Further, the CNO - was not only from the organic material, but also from nitrate in loading reagent in NTIMS. The isobaric interference in loading reagents may be a reason resulting to result in low boron isotopic ratios by NTIMS. So monitoring the mass 43 ion intensity and 43/42 ratio of blank are necessary for the boron isotopic measurement by NTIMS. The mixed solution of the MgCl 2 and NaOH is a suitable loading reagent for boron isotopic measurement by NTIMS.