ISO 7431-1:2024
Thiourea for industrial use — Part 1: Test methods
- Standard No.
- ISO 7431-1:2024
- Release Date
- 2024
- Published By
- International Organization for Standardization (ISO) IX / ISO
- Latest
- ISO 7431-1:2024
- Introduction
Analysis of the core content of the standard
As an important standard for the quality control of industrial thiourea (CAS 62-56-6), ISO 7431-1:2024 systematically regulates the methodology system of 9 major testing items. This standard is applicable to the testing of thiourea raw materials in industrial application scenarios such as rubber vulcanization accelerators and metal ore flotation agents.
Comparison of key detection methods
Detection items Method principle Core instruments Allowance deviation Thiourea content Iodometric redox titration 50mL burette (0.02mL graduation value) ≤0.2% Water insoluble matter Membrane filtration weighing method 0.45μm filter membrane+105℃ oven ≤20% relative deviation Calcium determination ICP-OES/AAS/ion chromatography Quartz crucible+850℃ muffle furnace ≤20% relative deviation
Technological evolution and innovation
Compared with the previous version of the standard, the main breakthroughs of the 2024 version are:
- Multi-method verification system: Calcium detection specifies three methods: ion chromatography (ISO 14911), ICP-OES (ISO 11885) and atomic absorption spectroscopy (ISO 7980), of which AAS is used as the arbitration method
- Safety warning upgrade: Added clear warning signs for thiourea skin contact toxicity and environmental hazards
- Digital detection: For melting point determination, it is recommended to use an automatic melting point instrument with an accuracy of ≥0.1℃ to replace the traditional capillary method
Implementation suggestions
- Method selection strategy: ICP-OES (4.8.3) is preferred for routine detection, and the AAS arbitration method (4.8.4) must be used in case of disputes
- Quality control points: When determining the thiourea content, the control of the dark reaction for 10 minutes directly affects the determination of the titration endpoint
- Safety protection requirements: The heavy metal detection operation (Chapter 4.9) must be carried out in a fume hood, and the thioglycerol solution must be prepared and used immediately
Standard traceability system
This standard integrates 8 ISO basic testing standards, including:
- ISO 3696 Specification for Water for Analytical Laboratories
- ISO 7027-1 Quantitative Determination of Turbidity
- ISO 11885 ICP-OES Elemental Analysis
ISO 7431-1:2024 Referenced Document
- ISO 10304-3:1997 Water quality - Determination of dissolved anions by liquid chromatography of ions - Part 3: Determination of chromate, iodide, sulfite, thiocyanate and thiosulfate
- ISO 11885:2007 Water quality - Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES)
- ISO 14911:1998 Water quality - Determination of dissolved Li<(hoch)+>, Na<(hoch)+>, NH<(Index)4><(hoch)+>, K<(hoch)+>, Mn<(hoch)2+>, Ca<(hoch)2+>, Mg<(hoch)2+>, Sr<(hoch)2+> and Ba<(hoch)2+> using ion chromatography - Method for water and waste water
- ISO 3165 Sampling of chemical products for industrial use; Safety in sampling
- ISO 3696 Water for analytical laboratory use; Specification and test methods
- ISO 6353-1:1982 Reagents for chemical analysis; Part 1 : General test methods
- ISO 7027-1 Water quality - Determination of turbidity - Part 1: Quantitative methods
- ISO 7980:1986 Water quality; Determination of calcium and magnesium; Atomic absorption spectrometric method
- ISO 8213 Chemical products for industrial use; Sampling techniques; Solid chemical products in the form of particles varying from powders to coarse lumps
ISO 7431-1:2024 history
- 2024 ISO 7431-1:2024 Thiourea for industrial use — Part 1: Test methods
- 2023 ISO 7431-1:2023 Thiourea for industrial use — Part 1: Test methods
