ASTM: D5996: Anionic Contaminants in High-Purity Water by On-Line Ion Chromatography
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Official Method Name
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Standard Test Method for Measuring Anionic Contaminants in High-Purity Water by On-Line Ion Chromatography |
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Current Revision
| Reapproved 2000. Current edition approved July 10, 1996. |
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Media
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WATER |
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Instrumentation
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Ion Chromatography |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Brief Method Summary
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A continuously flowing sample is injected into the instrument through a sample injection valve. The sample is pumped through a concentrator column where the anions of interest are collected on ion-exchange resin. After a suitable volume of sample has been passed through the concentrator column, sample flow is diverted and an eluant is pumped through the concentrator column to remove the trapped anions. This eluant then flows through an analytical column set where the anions are separated based on the retention characteristic of each anion relative to the eluant used. The eluant stream containing the anions of interest passes through a suppressor device where the cations from the eluant are exchanged for hydrogen ions, converting the anions to their acid form. After the suppressor device, the eluant solution passes through a conductivity detector where the separated anions are detected. Detection limits for the anions are enhanced because the anions are in the acid form rather than the salt. The anions are identified based on the retention time as compared to known standards. By measuring peak height or area and comparing the detector response to known standards, the anions can be quantified. |
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Scope and Application
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This test method covers on-line analysis of high-purity water by the ion chromatography technique. This test method is applicable for measuring various anionic contaminants in high-purity water, typically in the range of 0.02 to 100 ug/L. |
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Applicable Concentration Range
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0.02-100 ug/L |
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Interferences
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When working with low concentration samples, blanks, and standards, contamination can be a serious problem. Extreme care must be exercised in all phases of this test method. Absorption/desorption of anions on sample line wall deposits can change analytical results. A single anion present at a concentration significantly higher than other anions could mask closely adjacent peaks on the chromatogram. Low breakthrough volumes may be experienced when continuously monitoring for anions in water that has had its pH raised by ammonia, morpholine, or other additives. An anion having the same retention time as one of the anions of interest will result in erroneously high values for that anion. When loading a concentrator column, high concentrations of interfering anions may cause low breakthrough volumes of other anions. |
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Quality Control Requirements
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Sample Handling
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Collect the sample in accordance with Practice D 1066, Specification D 1192, and Practices D 3370. When volatile amines are used to control process pH, samples should be taken from the effluent of a rinsed strong acid resin exchange column. Typically on-line ion chromatography samples are taken from the effluent of cation resin columns used to continuously monitor cation conductivity. Samples taken from this source will have cation contaminants or additives such as ammonia removed by the cation resin. This will eliminate high pH conditions that can cause low breakthrough volumes. Process water such as boiling water reactor feedwater and water used in the semiconductor industry generally do not have pH additives, and sampling from the effluent of a cation resin column is not required. |
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Maximum Holding Time
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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