GB/T 15503-1995 in English
VALIDWater quality －Determination of vanadium －BPHA extraction spectrophotometric method
- Issued on:1995-01-19
- Implemented on:1995-08-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 15503-1995水质 钒的测定 钽试剂（BPHA）萃取分光光度法》由467（生态环境部）归口，主管部门为生态环境部。
本标准规定了测定水和废水中钒的钽试剂萃取分光光度法。本方法适用于水和废水中钒的测定。
Introduction
1. Introduction
GB/T 15503—1995 is the first national standard for the determination of vanadium content in water and wastewater in my country, using tantalum reagent (BPHA) extraction spectrophotometry. This method has become an important tool in the field of environmental monitoring due to its high sensitivity, simplicity and accuracy.
2. Comparison of standard frameworks
| Standard dimensions | GB/T 15503—1995 | ISO standard comparison | Nelson method |
|---|---|---|---|
| Detection principle | Tantalum reagent extraction spectrophotometry | Ion chromatography | Redox titration |
| Scope of application | Determination of vanadium content in water and wastewater | Drinking water and surface water | Industrial water monitoring |
| Sensitivity | Detection limit: 0.018 mg/L, upper limit of determination: 10.0 mg/L | Detection limit: 0.02 mg/L | Linear range: 0.5-10 mg/L |
| Accuracy | Laboratory relative standard deviation: 0.78%, recovery rate: 99.3% | Accuracy±5% | Relative error±10% |
3. Principle of determination
Tantalum reagent (BPHA) is a weak acid that can form a slightly soluble pink chelate with pentavalent vanadium under strong acidic conditions. The reaction is represented by the following equation:
V^{5+} + BPHA ↔ V(BPHA)_n^{}
Then, the mixture was extracted with chloroform and ethanol, and the spectrophotometric determination was performed at 440 nm.
4. Reagent and Instrument Requirements
4.1 Reagent Preparation Instructions
- Sulfuric acid (H₂SO₄): ρ=1.84 g/mL, used for acidification of samples.
- Phosphoric acid (H₃PO₄): ρ=1.69 g/mL, used as a buffer.
- Potassium permanganate solution: 0.5 g/100 mL, used for oxidation treatment of samples.
4.2 Instrument Configuration
- Spectrophotometer: Equipped with 1 cm absorption cell.
- Magnetic stirrer: Used to mix the extract.
- Conical flask with glass stopper: Capacity is 100 mL.
5. Determination steps
The determination process is divided into two stages: sample preparation and calibration curve establishment. First, potassium permanganate is used to oxidize the divalent vanadium in the sample, and urea and sodium nitrite are added to complete the redox reaction. Subsequently, phosphoric acid is added and diluted to a certain volume to form a suitable reaction environment.
6. Experimental results and analysis
Calculation formula for vanadium concentration in the sample:
C = m / V
Wherein, m is the vanadium content (μg) obtained from the calibration curve, and V is the sample volume (mL) taken during analysis.
7. Precision and accuracy
Multi-laboratory validation results show that this method has high precision and accuracy. The results of the determination of the unified standard solution by six laboratories showed that the relative standard deviation within the laboratory was 0.78%, the relative standard deviation between laboratories was 0.99%, and the average spike recovery rate was 99.3%.
8. Implementation recommendations
Sample collection and storage:Use polyethylene plastic bottles, immediately acidify with nitric acid to pH <2, and refrigerate. It is recommended to complete the analysis within 6 months.
Experimental condition control: Ensure the purity of reagents and instrument calibration, especially the wavelength accuracy of the spectrophotometer.
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