Standard Methods: 4500-B B: Boron by Curcumin Method
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Official Method Name
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4500-B B. Curcumin Method |
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Current Revision
| Standard Methods Online |
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Media
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WATER |
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Instrumentation
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Spectroscopy (Colorimetry; Photometry) |
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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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When a sample of water containing boron is acidified and evaporated in the presence of curcumin, a red-colored product called rosocyanine is formed. The rosocyanine is taken up in a suitable solvent and the red color is compared with standards visually or photometrically. |
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Scope and Application
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The curcumin method is applicable to determining boron in water in the 0.10 to 1.0 mg/L range. The range of this method can be extended by dilution or concentration of the sample. |
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Applicable Concentration Range
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0.10 to 1.0 mg/L (general); 0.05-0.2 mg/L (adapted) |
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Interferences
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Nitrate-N concentrations above 20 mg/L interfere. Significantly high results are possible when the total of calcium and magnesium hardness exceeds 100 mg/L as calcium carbonate. Moderate hardness levels also can cause a considerable percentage error in the low boron range. This interference springs from the insolubility of the hardness salts in 95% ethanol and consequent turbidity in the final solution. |
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Quality Control Requirements
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See Section 4020 Quality Assurance/Quality Control. |
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Sample Handling
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Store samples in polyethylene bottles or alkali-resistant, boron-free glassware. Preserve to pH <2 with nitric acid. |
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Maximum Holding Time
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6 months (regulatory) (See Section 1060) |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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