水质.溶解氧的测定 电化学探头法

[中文适用范围]： 本国际标准规定了通过电化学电池测定水中溶解氧的电化学方法，该电化学电池通过透气膜与样品隔离。 测量可以以每升毫克为单位的氧浓度、饱和度百分比（溶解氧百分比）或两者兼而有之。 该方法测量水中对应于 1% 至 100% 饱和度的氧气。 然而，大多数仪器允许测量高于 100% 的值，即过饱和。 注：当氧分压高于空气中的分压时，可能会出现过饱和。 特别是当藻类生长旺盛时，可能会出现高达 200% 及以上的过饱和度。 当采取特殊措施以防止在样品处理和测量过程中氧气逸出时，该方法可测量饱和度高于 100% 的水中的氧气。 该方法适用于现场测量和溶解氧的连续监测，以及实验室测量。 它是分析高色度和浑浊水的首选方法，也适用于分析因铁和碘固定物质而不适用于温克勒滴定法的水，这些物质会干扰 ISO 5813[1] 中规定的碘量法。 该方法适用于饮用水、天然水、废水和盐水。 如果用于咸水，例如海水或河口水域，则必须进行盐度校正。 [外文原描述]： ISO 5814:2012 specifies an electrochemical method for the determination of dissolved oxygen in water by means of an electrochemical cell which is isolated from the sample by a gas permeable membrane. Measurement can be made either as a concentration of oxygen in milligrams per litre, percentage saturation (% dissolved oxygen) or both. The method measures oxygen in water corresponding to 1 % to 100 % saturation. However, most instruments permit measurement of values higher than 100 %, i.e. supersaturation. The method measures oxygen in water with a saturation higher than 100 %, when special arrangements to prevent the outgassing of oxygen during the handling and measurement of the sample are made. The method is suitable for measurements made in the field and for continuous monitoring of dissolved oxygen, as well as measurements made in the laboratory. It is the preferred method for highly coloured and turbid waters, and also for analysis of waters not suitable for the Winkler titration method because of iron- and iodine-fixing substances, which can interfere in the iodometric method specified in ISO 5813. The method is suitable for drinking waters, natural waters, waste waters, and saline waters. If used for saline waters, such as sea or estuarine waters, a correction for salinity is essential.