What is ISO 1656 – Rubber, raw natural, and rubber latex, natural about ?
ISO 1656 specifies a macro-method and a semi-micro method for the determination of nitrogen in raw natural rubber and natural rubber latex using variants of the Kjeldahl process.
The purpose of ISO 1656 is to develop a method of determination of the nitrogen in natural rubber by Kjeldahl process using non-toxic catalyst (no selenium in catalyst mixture). This method is easy to operate, safe and environment-friendly. It also does not need alternative analyser.
Note: The determination of nitrogen in natural rubber is usually carried out in order to arrive at an estimate of the protein content. Minor amounts of non-proteinous nitrogen-containing constituents are also present. However, in the dry solids prepared from natural rubber latex, these materials can make a substantial contribution to the total nitrogen content.
Who is ISO 1656 – Rubber, raw natural, and rubber latex, natural for ?
ISO 1656 on rubber, raw natural, and rubber latex, natural is relevant to:
- Product Engineers
- Chemical Engineer
- Manufacturers of rubber products
- Researchers and scientists
Why should you use ISO 1656 – Rubber, raw natural, and rubber latex, natural ?
The Kjeldahl method involves heating a sample to 360-410°C with concentrated sulfuric acid, which by oxidation decomposes the organic sample to liberate the nitrogen as ammonium sulphate.
ISO 1656 provides a method for determining nitrogen content in natural rubber by the Kjeldahl process using a non-toxic catalyst, which provides the processors with an easy-to-use, safe and eco-friendly method with no alternative test.
ISO 1656 contains methods and procedures for preparing and sampling rubber and latex test specimens, thereby providing the manufacturers and processors with standardized rules and specifications.
ISO 1656 aims to benefit the end-user by acting as a comprehensive guide to determine the nitrogen content of rubber or natural rubber, so that it can be processed efficiently, have higher strength, be more flexible and cost-efficient.
What is changed since the last update ?
ISO 1656:2019 supersedes ISO 1656:2016, which is withdrawn. ISO 1656:2019 has some technical changes concerning ISO 1656:2016. These include:
- An introduction has been added to explain the purpose of this revision
- In clause 4, a known mass of the sample is now digested with a mixture of sulfuric acid and catalytic amounts
- The list of reagents in 5.1 and 6.1 has been updated
- In the formulae, the exact concentration of the standard volumetric solutions is expressed in eq/dm3 with three significant decimal figures
- The content of total solids in latex has been changed from 2 g to 10 g in 5.3, and from 0,1 g of total solids to 5 g in 6.3
- In 5.4.1, the tolerance on the weighting of the sample has been changed from 0,5 mg to 0,1 mg and the amount of catalyst mixture has been added
- In 5.5, a note has been added to warn of the non-conformance of the blank test
- In figures 8 and 10, the length of the condenser has been changed from 250 mm to 300 mm; and the length of the condenser tube has been changed from 500 mm to 600 mm
- In clause 8, the note has been deleted since the concentrations of the standard volumetric solutions used have been standardization
- The precision data have been updated according to the result of the ITP and former Annex A has been deleted
