【国外标准】 Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium in Water and Wastewater by Ion Chromatography

5.1 This test method is applicable to the simultaneous determination of dissolved alkali and alkaline earth cations and ammonium in water and wastewaters. Alkali and alkaline earth cations are traditionally determined by using spectroscopic techniques, such as AAS or ICP; whereas ammonium can be measured by using a variety of wet chemical methods, including colorimetry, ammonia-selective electrode, and titrimetry. However, ion chromatography provides a relatively straightforward method for the simultaneous determination of cations, such as lithium, sodium, potassium, calcium, magnesium, and ammonium, in fewer than 20–30 min.1.1 This test method is valid for the simultaneous determination of the inorganic alkali and alkaline earth cations, lithium, sodium, potassium, magnesium, and calcium, as well as the ammonium cation in reagent water, drinking water, and wastewaters by suppressed and nonsuppressed ion chromatography.1.2 The anticipated range of the test method is 0.05–200 mg/L. The specific concentration ranges tested for this test method for each cation were as follows (measured in mg/L):Lithium 0.4–10.0Sodium 4.0–40.0Ammonium 0.4–10.0Potassium 1.2–20.0Magnesium 2.4–20.0Calcium 4.0–40.01.2.1 The upper limits may be extended by appropriate dilution or by the use of a smaller injection volume. In some cases, using a larger injection loop may extend the lower limits. It is the responsibility of the user to ensure the validity of this test method for concentrations if the range is extended.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 It is the user’s responsibility to ensure the validity of these test methods for waters of untested matrices.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For hazards statements specific to this test method, see 8.3.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.