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.
ISO 1656 on rubber, raw natural, and rubber latex, natural is relevant to:
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.
ISO 1656:2019 supersedes ISO 1656:2016, which is withdrawn. ISO 1656:2019 has some technical changes concerning ISO 1656:2016. These include:
ISO 1656