EPA-OGWDW/TSC: 302.0: Bromate in Drinking Water Using 2-D IC With Suppressed Conductivity Detection
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Official Method Name
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Determination of Bromate in Drinking Water Using Two-Dimensional Ion Chromatography With Suppressed Conductivity Detection |
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Current Revision
| Version 1.0 September 2009 |
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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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EPA, 2009: Method 302.0: Determination of bromate in drinking water using two-dimensional ion chromatography with suppressed conductivity detection: Office of Water, EPA 815-B-09-014. |
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Brief Method Summary
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A 1.0-mL sample aliquot is injected onto a 4-mm IC column. Separation of bromate is achieved in the first dimension (1-D) using 10 mM KOH at a flow rate of 1.0 mL per minute. Approximately 2 mL of the suppressed eluent containing the bromate is diverted from the first dimension column to a concentrator column used in place of the sample loop of the second dimension (2-D) injection valve. The concentrator column has low backpressure but sufficient capacity to trap the bromate ions quantitatively in the suppressed eluent. In this manner, bromate is separated from other matrix ions and concentrated on a trapping column. The heart-cut portion of the 1-D chromatogram is eluted off the concentrator column and onto a smaller diameter (2 mm diameter) guard and analytical column that have different selectivity from the first dimension columns to facilitate the 2-D separation using 10 mM KOH at a flow rate of 0.25 mL per minute. Bromate is quantitated using the external standard method. |
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Scope and Application
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This is a large volume (1.0 mL), two-dimensional (2 D) ion chromatographic (IC) method using suppressed conductivity detection for the determination of bromate in raw and finished drinking waters. Because this method utilizes two dissimilar IC columns it does not require second column confirmation. Detection and quantitation in the second dimension are accomplished by suppressed conductivity detection. |
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Applicable Concentration Range
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Dependent upon calibration range of instrumentation. |
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Interferences
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Interferences can be divided into three different categories: (i) direct chromatographic coelution, where an analyte response is observed at very nearly the same retention time (RT) as the target analyte; (ii) concentration dependant co-elution, which is observed when the response of higher than typical concentrations of the neighboring peak overlaps into the retention window of the target analyte; and (iii) ionic character displacement, where retention times may significantly shift due to the influence of high ionic strength matrices (high mineral content or total dissolved solids) overloading the exchange sites on the column and significantly shortening the target analyte's retention time. |
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Quality Control Requirements
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Quality Control requirements include the Initial Demonstration of Capability (IDC) and ongoing QC requirements that must be met when preparing and analyzing field samples. The QC criteria are summarized in Section 17, Tables 4 and 5 of EPA Method 302.0. |
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Sample Handling
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Samples must be dechlorinated at the time of collection by adding EDA so that the final concentration in the sample container is 50 mg/L. Field samples must be chilled during shipment and must not exceed 10 degrees C during the first 48 hours after collection. Field samples should be confirmed to be at or below 10 degrees C when they are received at the laboratory. Field samples stored in the lab must be held at or below 6 degrees C until analysis. |
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Maximum Holding Time
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Field samples that are collected and stored as specified may be held for up to 28 days. |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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