ASTM D6581-18 pdf free.Standard Test Methods for Bromate, Bromide, Chlorate, and Chlorite in Drinking Water by Suppressed Ion Chromatogra.
1. Oxyhalides (chlorite, bromate, and chlorate) and bromide in raw water, finished drinking water and bottled water are determined by ion chromatography. A sample (200 μL) is injected into an ion chromatograph and the pumped hydroxide eluent sweeps the sample through the analytical column set.Here, anions are separated from the sample matrix according to their retention characteristics, relative to the anions in the eluent.
2.1 The separated anions in the eluent stream then pass through a suppressor device, where all cations are exchanged for hydronium ions. This converts the eluent to water, thus reducing the background conductivity. This process also converts the sample anions to their acid form, thus enhancing their conductivity. The eluent stream then passes through a conductivity cell, where they are detected. An appropriate computerbased data system is typically used for data presentation.
2.2 The anions are identified based on their retention times compared to known standards. Quantification is accomplished by measuring anion peak areas and comparing them to the areas generated from known standards.
3.1 Positive errors can be caused by progressive oxidation
of residual hypochlorite or hypobromite, or both, in the sample to the corresponding chlorate and bromate. Furthermore, chlorite can also be oxidized to chlorate, causing negative errors for chlorite and positive errors for chlorate. These interferences are eliminated by the sample preservation steps outlined in 26.3. Chloride present at >200 mg/L and carbonate present at >300 mg/L can interfere with bromate determination. These interferences can be minimized, or eliminated, by the sample pretreatment steps outined in 26.4. Fluoride and low molecular weight monocarboxylic acids, present at mg/L concentrations, may interfere with the quantitation of chlorite and bromate.
24.1 lon Chromatography Apparatus Analyical systemcomplete with all required accessories, including eluent pump,injector, syringes, columns, suppressor, conductivity detector,data system and compressed gasses.ASTM D6581 pdf download.
ASTM D6581-18 pdf free
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