DIRECT DETERMINATION OF IODIDE IN SEAWATER BY CATHODIC STRIPPING SQUARE-WAVE VOLTAMMETRY
DIRECT DETERMINATION OF IODIDE IN SEAWATER BY CATHODIC STRIPPING SQUARE-WAVE VOLTAMMETRY
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DOI：
10.1021/ac00168a017
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发表时间：
1988-09-01
影响因子：
7.4
通讯作者：
ULLMAN, WJ
中科院分区：
文献类型：
--
作者：
LUTHER, GW;SWARTZ, CB;ULLMAN, WJ
本文介绍了一种直接测定海水中碘的方法。通过使用阴极溶出方波伏安法，可以测定海水、淡水和微咸水中的低和亚纳摩尔水平的碘化物。精度通常为±5%（1）。最低检测限为0.1-0.2 nM（万亿分之12），沉积时间为180秒。从大西洋样本中获得的数据显示出与以前报告的碘形态数据相似的趋势。该方法比以前的方法灵敏1-2个数量级。在样品中加入Triton X-100可提高汞电极对碘化物的灵敏度。碘酸盐和碘化物是海水中碘的两种主要形式（1）。到目前为止，测定海洋沃茨中碘形态的主要方法集中在使用差示脉冲极谱法分析碘酸盐的五电子不可逆波（2，3）或在酸性溶液中转化为I3“后对IO 3 * 进行比色测定（4，5）。在每种方法中，碘酸盐直接在样品上测定。总碘通过化学方法（3，5）或光化学方法（2）将碘化物和有机碘化合物转化为碘酸盐来测定。因此，碘化物和有机碘是通过差异来确定的。用示差脉冲极谱法测得碘酸根的最低检测限接近20 nM。对于比色法，海水中的最低检测限（MDL）为30-50 nM。然而，在淡水和河口水中，由于天然存在的有机物在I3~检测波长（350 nm）处的UV吸收，MDL较高。海水中的总碘浓度（35%o）约为470 nM（2，4-7）。在表层海洋沃茨中，碘酸盐浓度接近300-400 nM，碘化物浓度可接近100-200 nM（2，4）。在深度上碘酸盐是唯一
A procedure for the direct determination of Iodide In seawater is described. By use of cathodic stripping square wave voltammetry, It Is possible to determine low and subnánomolar levels of iodide In seawater, freshwater, and brackish water. Precision Is typically±5%(1). The minimum detection limit Is 0.1-0.2 nM (12 parts per trillion) at a 180-s deposition time. Data obtained on Atlantic Ocean samples show similar trends to previously reported iodine speciation data. This method is more sensitive than previous methods by 1-2 orders of magnitude. Triton X-100 added to the sample enhances the mercury electrode's sensitivity to iodide.Iodate and iodide are the two principal forms of iodine in seawater (1). To date, the principal methods for determining iodine speciation in marine waters have centered on the analysis of the five-electron irreversible wave of iodate using differential pulse polarography (2, 3) or the colorimetric de-termination of IO3* after conversion to I3 “in acidic solution (4, 5). In each method iodate is determined directly on a sample. Total iodine is determined by converting iodide and organic iodine compounds to iodate via chemical (3, 5) or photochemical means(2). Thus, iodide and organic iodine are determined by difference. The minimum detectable limit of iodate obtained by using thedifferential pulse polarography method is near 20 nM. For the colorimetric method, the minimum detectable limit (MDL) is 30-50 nM in seawater. However, in freshwater and estuarine water, the MDL is higher due to UV absorption by naturally occurring organic matter at the wavelength for I3~ detection (350 nm). Total iodine concentration in seawater (35% o) is approximately 470 nM (2, 4-7). In surface ocean waters, iodate concentrations are near 300-400 nM and iodide concentrations can approach 100-200 nM (2, 4). At depth, iodate is the only