应用Hydra C全自动汞分析系统对土壤中总汞量的测定进行了研究。土壤样品经研磨并通过孔径0.15 mm筛。称取一定量的样品(0.1 g)置于样舟中,直接由氧气(载气)自动送入仪器的热解炉中,经干燥(300 ℃),热解(800 ℃)和催化还原(600 ℃)后进入金汞齐化器选择性吸收汞。然后加热汞齐释出汞蒸气,通过吸收池,用原子吸收光谱法在波长253.65 nm处测得其吸收值。采用土壤标准物质由仪器自动制备汞含量在30.0 ng以内以及30.0~300.0 ng范围内的高、低浓度两条标准曲线。用2个含汞样品进行分析,得到测定结果的相对标准偏差(n=6)均小于2.0%。在无样品及称有0.1 g样品条件下,分别进行10次测定,测得仪器和方法的检出限(3s)依次为0.022,0.082 ng。对7件土壤样品分别用本法与原子荧光光谱法测定其汞量,经t检验法检验,表明两组数据间无显著差异。

Study on the determination of total mercury in soil was performed using the Hydra C automatic mercury analytical system. The soil sample was pulverized to pass through sample sieve with aperture size of 0.15 mm. A portion of soil sample (0.1 g) was placed into the sample boat and introduced automatically into the pyrolysis furnance of the analyt. system by the carrier gas of oxygen, and proceeded to stages of drying (at 300 ℃), pyrolysis (at 800 ℃) and catalytic reduction (at 600 ℃) after which mercury was selectively isolated by amalgamation with gold. Mercury was then liberated from the amalgam by heating and the Hg vapour was passed through absorption cell and its absorbance measured by AAS at the wavelength of 253.65 nm. CRM′s of soil were used for preparation of 2 standard curves in the linearity ranges of within 30.0 ng and between 30.0-300.0 ng by the analyt. system automatically. Precision was tested with 2 samples containing of Hg, and values of RSD′s (n=6) obtained were all less than 2.0%. Ten determinations were carried out without and with (0.1 g) sample, values of detection limits (3s) found for the instrument and for the method were 0.022 ng and 0.082 ng respectively. Seven soil CRM′s were analyzed by the present method and by the AFS method, as shown by the result of t-test, no significant difference was found between the results of the 2 methods.