This standard uses Zeisel gas chromatograph technology to determine the degree of methoxy and hydroxypropyl substitution in cellulose ethers. The level of substitution has a significant impact on the solution properties, rheology and viscosity of cellulose ethers. This test method is suitable for cellulose ether products with high degree of substitution, but does not apply to hydroxypropyl cellulose. Not all safety issues are covered in the standard. Users need to develop appropriate safety measures and ensure compliance with relevant regulations.