Where can I buy the reference substance? Reference substance says

      

　　Where can I buy the reference material? Generally usedLegal reference substance of the Institute of Drug Control, during the development process, you can calibrate some of the working references by yourself. Purchases can be inquired and purchased on the National Standard Products Network.

　　How to check the valid period of the reference substance manual? Most of the reference substances do not have instructions, and the self-made reference substances have an electronic version of the quality inspection report. Normally, you can find the relevant reference substance manufacturer to provide it after you buy the reference substance. The reference substance manual of the China Inspection Institute can be searched on the www.gbw.org.cn National Standard Products Network Click to view or contact online sales consultation. Imported instructions are generally paper with the goods, depending on the product

　　How to check the valid period of the final reference substance? There is no valid period for the reference substance, and all products are subject to the official notice. For example, if some reference substances were produced in 2006, if they are still on sale, then the valid period is not available. If there is still a 2006 batch but no sales and a new batch of 2018 appears, then the valid period of 2006 will expire. For details, it depends on different brands and products to make a decision.