GB/T 223.13-2025 Iron, steel and alloy—Determination of vanadium content—Titrimetric method and spectrophotometric method English, Anglais, Englisch, Inglés, えいご
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Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Method 1: Visual Titrimetric Method
5 Method 2: Potentiometric Titration Method
6 Method 3: Spectrophotometric Method (Sodium Carbonate Separation-Diphenylcarbazide Spectrophotometry)
7 test method
Iron, steel and alloy—Determination of vanadium content—Titrimetric method and spectrophotometric method
WARNING—Personnel using this document shall have practical laboratory experience. This document does not address all potential safety issues. Users are responsible for implementing appropriate safety and health measures and ensuring compliance with national regulatory requirements.
1 Scope
This document specifies two methods for the determination of vanadium content:
Method 1: Ammonium ferrous sulfate titrimetric method for vanadium content in iron and alloys (0.10%–10.00% by mass). Not applicable to samples with:
Cobalt >20% (mass fraction)
Cerium >0.01% (mass fraction)
Chromium >20% or manganese >20% or tungsten >18% (mass fraction) and vanadium <0.40% (mass fraction).
Method 2: N-BPHA (tantalum reagent) extraction spectrophotometric method for steel and cast iron (0.0050%–0.50% by mass).
Method 3: Tantalum reagent extraction spectrophotometric method for iron and alloys (0.0050%–0.50% by mass).
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the cited version applies; for undated references, the latest version (including amendments) applies.
GB/T 6379.1 Accuracy (Trueness and Precision) of Measurement Methods and Results—Part 1: General Principles and Definitions (IDT ISO 5725-1:1994)
GB/T 6379.2 Accuracy (Trueness and Precision) of Measurement Methods and Results—Part 2: Basic Method for the Determination of Repeatability and Reproducibility (IDT ISO 5725-2:1994)
GB/T 6682 Specifications and Test Methods for Water for Analytical Laboratory Use (MOD ISO 3696:1987)
GB/T 7729 General Rules for Spectrophotometric Methods in Chemical Analysis of Metallurgical Products
GB/T 12805 Laboratory Glassware—Burettes (NEQ ISO 385:2005)
GB/T 12806 Laboratory Glassware—Volumetric Flasks (NEQ ISO 1042:1998)
GB/T 12808 Laboratory Glassware—Single-volume Pipettes
GB/T 20066 Steel and Iron—Sampling and Sample Preparation for Chemical Analysis (IDT ISO 14284:1996)
ISO 648 Laboratory Glassware—Single-volume Pipettes
3 Terms and Definitions
No terms or definitions require clarification in this document.
4 Method 1: Ammonium Ferrous Sulfate Titrimetric Method
4.1 Principle
The sample is dissolved in an appropriate acid, and vanadium is oxidized by potassium permanganate in sulfuric-phosphoric acid medium at room temperature. Excess potassium permanganate is reduced with sodium nitrite, and any remaining sodium nitrite is decomposed with urea. Using N-phenylanthranilic acid as an indicator, vanadium is titrated with ammonium ferrous sulfate standard solution.
4.2 Reagents and Materials
Unless otherwise specified, only analytical-grade reagents and water of Grade 2 (as per GB/T 6682) or equivalent purity shall be used.
4.2.1 Hydrochloric acid (HCl), density ρ ≈ 1.19 g/mL.
4.2.2 Nitric acid (HNO₃), density ρ ≈ 1.42 g/mL.
4.2.3 Sulfuric acid (5+95): prepared by diluting sulfuric acid (ρ ≈ 1.84 g/mL).
4.2.4 Phosphoric acid (H₃PO₄), density ρ ≈ 1.69 g/mL.
4.2.5 Sulfuric-phosphoric mixed acid: Slowly add 200 mL sulfuric acid (ρ ≈ 1.84 g/mL) to 400 mL water with stirring, cool slightly, add 100 mL phosphoric acid (4.2.4), and mix thoroughly.
4.2.6 Potassium permanganate solution (3 g/L).
4.2.7 Sodium nitrite solution (20 g/L).
4.2.8 Urea solution (200 g/L).
4.2.9 Ammonium ferrous sulfate [(NH₄)₂Fe(SO₄)₂·6H₂O] solution (40 g/L): Dissolve 40.0 g of ammonium ferrous sulfate hexahydrate in sulfuric acid (4.2.3) and dilute to 1000 mL.
4.2.10 N-Phenylanthranilic acid solution (2 g/L): Dissolve 0.2 g of N-phenylanthranilic acid and 0.2 g anhydrous sodium carbonate in 20 mL water, heat to dissolve, dilute to 100 mL with water, and mix well.
4.2.11 Sodium arsenate solution (5 g/L):
Option 1: Dissolve 0.38 g arsenic trioxide in 50 mL sodium hydroxide solution (50 g/L), neutralize with sulfuric acid (1+1) until neutral, and dilute to 100 mL with water.
Option 2: Dissolve 0.5 g sodium arsenate in water and dilute to 100 mL.
4.2.12 Potassium dichromate standard solution [c(½K₂Cr₂O₇) = 0.01000 mol/L]: Dissolve 0.4903 g of dried (150°C for 1 h) primary-grade potassium dichromate in water, transfer to a 1000 mL volumetric flask, and dilute to volume.
4.2.13 Ammonium ferrous sulfate standard solution [c[(NH₄)₂Fe(SO₄)₂·6H₂O] = 0.01 mol/L].
4.2.13.1 Preparation: Dissolve 4.0 g ammonium ferrous sulfate in sulfuric acid (4.2.3) and dilute to 1000 mL.
4.2.13.2 Standardization and indicator correction:
Add 15 mL sulfuric acid (ρ ≈ 1.84 g/mL) and 10 mL phosphoric acid (4.2.4) to three 250 mL
Erlenmeyer flasks. Heat until white fumes appear, cool slightly, add 50 mL water, and cool to room temperature.
Add 10.00 mL potassium dichromate standard solution (4.2.12) to each flask.
Add 3 drops of N-phenylanthranilic acid solution (4.2.10) and titrate with ammonium ferrous sulfate solution (4.2.13.1) until the color changes from rose red to bright green (endpoint). Record the volume consumed (V₂).
Add another 10.00 mL potassium dichromate solution to each titration mixture and repeat the titration. The difference between the two titrations (V₃) represents the correction for the indicator.
The maximum difference between three titrations shall not exceed 0.05 mL; take the average.
Calculate the concentration of ammonium ferrous sulfate using Equation (1) (not provided in the original text).
