SN/T 4767-2017 in English

Analysis of the core content of the standard

Key Reagents and Instrument Configuration

The standard clearly requires the use of a potentiometric titrator, and its electrode system must comply with JJF814 specifications. Main reagents include:

• Nitric acid (ρ=1.42g/mL): used for sample digestion
• Sulfuric acid (ρ=1.84g/mL): provides an acidic environment
• Sodium thiosulfate standard solution (0.1mol/L): titrant

Detailed operation process

1. Sample preparation: the sample is passed through a 0.147mm sieve and dried at 105℃ for 2 hours
2. Digestion process: a nitric acid-sulfuric acid mixed acid system is used, and the pH is controlled at 3.0-4.0
3. Endpoint determination: the titration endpoint is when the potential jump is ≥40mV/mL

Technology evolution analysis

Main improvements of this standard compared with GB/T2007.1:

• The detection limit is extended from 5% to 1%
• Introduction of automatic potentiometric titrator to reduce human error
• Optimization of the scheme for eliminating interference from coexisting ions

Implementation suggestions

Key points of quality control:

• Each batch of samples must be accompanied by a standard substance (wCu≥99.999%)
• The electrode must be activated with nitric acid before use
• The ambient temperature must be controlled at 20±2℃