Standard Operating Procedure (SOP): Develop detailed SOPs for various production processes such as feeding, reaction condition control (temperature, pressure, duration, etc.), and product post-processing to ensure standardized production. For example, in the production of hydroxypropyl chitosan, it is necessary to strictly follow the prescribed temperature，etc.

Qualification review: A professional team reviews the licenses and permits of raw material suppliers such as chitosan, considers industry experience, and selects enterprises with good reputation.
Field visit: Visit key suppliers, inspect workshop layout, equipment condition, and storage conditions, and evaluate the automation level of chitosan production equipment.
System evaluation: Review quality manuals and other documents, refer to internal audit and sampling records, and assess supplier quality control capabilities.

Appearance: Quality inspectors inspect the color and clumping of chitosan, as well as the crystal morphology of azelaic acid and salicylic acid. Any abnormal raw materials are further inspected or rejected.
Purity: Use HPLC to measure the purity of the raw materials, and return any that do not meet the standards.
Indicator testing: Based on the characteristics of different raw materials, such as the degree of deacetylation of chitosan, chemical titration is used to ensure compliance before qualified raw materials can enter production.

Operation guide: Develop operating standard procedures and clarify the feeding sequence.
Condition control: Strictly control the reaction temperature, pressure, and time to ensure stable reaction.
Post processing: Clarify the parameters such as the number of times the product is washed and dried, solvent, temperature, etc., and use low-temperature vacuum drying to ensure quality.

Daily cleaning: Operators clean the equipment before and after each shift, inspect the appearance and components.
Regular maintenance: Develop a plan, have professional personnel deeply maintain key equipment, and calibrate precision instruments.
Performance verification: Conduct regular trial production and determine whether the equipment needs to be adjusted based on product quality indicators.

Skill training: Regularly conduct professional training on production processes, quality control, and invite experts to share technical methods.
Awareness enhancement: Enhance employees' quality awareness through training and posting slogans.
Operation supervision: Establish a supervision post to correct illegal operations and educate and assess personnel to ensure production follows SOP.