Main Detection Items and Standard Methods
The detection of methylcellulose mainly includes the determination of viscosity, methoxyl content, pH, loss on drying, residue on ignition, heavy metals, and arsenic salts. Viscosity determination should be based on pharmacopoeia standards. For samples with a labeled viscosity below 600 mPa·s, the capillary viscometer method should be used, and the viscosity should be 80%–120% of the labeled viscosity. For samples with a labeled viscosity not less than 600 mPa·s, the rotational viscometer method should be used, and the viscosity should be 75%–140% of the labeled viscosity. The methoxyl content determination should follow the methoxyl determination method and can be performed using gas chromatography or titration. Other routine tests include pH, loss on drying, residue on ignition, heavy metals, and arsenic salts.
For pH testing, the solution from the viscosity section should be tested according to the method described above. The pH value should be 5.0–8.0. Loss on drying test: Dry the product at 105℃ for 1 hour; the weight loss should not exceed 5.0%. Residue on ignition test: Test 1.0g of the product according to the method; the residue should not exceed 1.0%. Heavy metal test: Test the residue remaining under the residue on ignition test according to the method; the heavy metal content should not exceed 20 parts per million. Arsenic test: Take 1.0g of the product, add 1.0g of calcium hydroxide, mix, ignite, and test according to the method; it should meet the requirements.
Other testing items and instruments
In addition, testing items include moisture content, purity analysis, and particle size distribution. Commonly used testing instruments include high-performance liquid chromatography (HPLC), infrared spectroscopy, and particle size analyzer.
Frontier testing technologies and research
In terms of testing technology research, Shandong Tiansheng Cellulose Co., Ltd. applied for a patent in October 2024 for "A method for detecting cellulose content in methylcellulose production wastewater." Two-dimensional correlation infrared spectroscopy can be used to characterize its dissolution mechanism in ionic liquids.
