EPA-EAD: 605: Benzidenes in Water Using HPLC/ED
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Official Method Name
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Benzidines |
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Current Revision
| 40 CFR Part 136, Appendix A (Current Edition) |
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Media
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WATER |
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Instrumentation
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High Performance Liquid Chromatography with Electrochemical Detection |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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A 1-L sample is extracted with chloroform in a separatory funnel. The chloroform extract is extracted with acid. The acid extract is then neutralized and extracted with chloroform. The final chloroform extract is exchanged to methanol while being concentrated using a rotary evaporator. The extract is mixed with buffer and the concentrations of benzidines are measured using a high performance liquid chromatography (HPLC) system equipped with an electrochemical detector (ED). |
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Scope and Application
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This method determines certain benzidines in wastewater and other waters. |
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Applicable Concentration Range
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Ranges differ for each analyte depending on matrix and interferences. |
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Interferences
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(A) Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse. (B) Reagent contamination: Use high purity reagents. (C) Extracted interferences: Interference from extracted non-target compounds, with retention times similar to target compounds, can be reduced by performing a cleanup procedure. (D) Compounds in dye plant effluents: Interference with benzidine determination by compounds in dye plant effluents can be avoided by reducing the electrode potential. |
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Quality Control Requirements
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Each laboratory that uses this method is required to operate a formal quality control program. The minimum requirements of this program consist of an initial demonstration of laboratory capability and an ongoing analysis of spiked samples to evaluate and document data quality. The laboratory must maintain records to document the quality of data that is generated. Ongoing data quality checks are compared with established performance criteria to determine if the results of analyses meet the performance characteristics of the method. When results of sample spikes indicate atypical method performance, a quality control check standard must be analyzed to confirm that the measurements were performed in an in-control mode of operation. |
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Sample Handling
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Grab samples must be collected in glass containers. [Note: Do NOT pre-rinse bottles]. Composite samples should be collected in refrigerated glass containers in accordance with the requirements of the program. Automatic sampling equipment must be as free as possible of Tygon tubing and other potential sources of contamination. All samples must be iced or refrigerated at 4oC and stored in the dark from the time of collection until extraction. Both benzidine and 3,3-dichlorobenzidine are easily oxidized. Fill the sample bottles and, if residual chlorine is present, add 80 mg of sodium thiosulfate per liter of sample and mix well. EPA Methods 330.4 and 330.5 may be used for measurement of residual chlorine. Field test kits are available for this purpose. After mixing, adjust the pH of the sample to a range of 2-7 with sulfuric acid. If 1,2-diphenylhydrazine is likely to be present, adjust the pH of the sample to 4.0 +/-0.2 to prevent rearrangement to benzidine. All samples must be extracted within seven days of collection. Extracts may be held up to seven days before analysis, if stored under an inert (oxidant free) atmosphere. The extract should be protected from light. |
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Maximum Holding Time
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Extract w/in 7 days; Analyze extracts w/in 7 days if held properly. |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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