碱化保存淡水及海水样品测定甲基汞和总汞

本文研究了水样保存条件对汞分析物稳定性的影响。常规总汞分析酸化水样保存法只适用于保存寒冷冬季水样测定甲基汞，而夏季水样在酸化保存过程中甲基汞会转化为无机汞。碱化（ｐＨ＞１２）保存天然水样可以防止甲基汞无机化，并且同时适用于长期室温保存冬季和夏季水样测定甲基汞和总汞。聚氟塑料瓶、聚丙烯塑料瓶、聚乙烯塑料瓶和硼玻璃瓶均可用于保存碱化水样测定甲基汞，但只有前两种容器同时适用于总汞分析水样保存。本文认为天然水样中的微生物是水样保存过程中导致甲基汞无机化的主要因素。

Alkaline Preservation of Fresh and Sea Water Samples for Methylmercury and Total Mercury Determinations

The storage behavior of both methylmercury and inorganic mercury spiked in sea and lake water samples stored in Teflon,polypropylene,polyethylene,and Pyrex glass containers has been investigated in detail.The stability of the mercury species spiked in natural water samples during storage period is strongly dependent on the pH of water samples.At pH<2,methylmercury is stable in the winter water samples,but does not in the summer water samples.At pH>12,methylmercury is stable for at least five weeks in the water samples (collected both in winter and in summer time)stored in all the containers tested.However,only the bottles made of Teflon and polypropylene provide reliable total mercury results for the water samples at pH>12.The demethylation of methylmercury in natural water samples during storage period is mainly due to the action of microorganisms in the sample solution.