在部分化工产品标准中,当某些检验项目不是最主要的控制项目时、常对其采用不每批都检验的作法(其它项目仍是每批检验)。但这些项目并非永远不检验,而是按要求至少在规定的“检验周期”内检验一次。当遇有新产品投产、工艺变化、更换设备、变换原料、产品长期停产后又恢复生产或生产不正常等各种可能影响产品质量的情况时,都应进行检验(或增加测定次数)。以上情况在过去的一些化工产品标准中,称为“抽检项目”或“保证指标”。其含意是:该(指标)项目不必每批产品都检验,但生产厂应保证出厂产品中该项目符合 In some chemical product standards, when some inspection items are not the most important control items, the practice of not testing each batch is often used (other items are still each batch of inspections). However, these items are not always tested but they are required to be tested at least once within the specified “test period”. Whenever a new product is put into production, the process is changed, the equipment is replaced, the raw materials are changed, the production is stopped after the product has been suspended for a long time, or the production is not normal, etc., which may affect the quality of the product, inspection (or increasing the number of measurements) shall be conducted. The above conditions are referred to as “sampling items” or “guaranteed indicators” in some past chemical product standards. The implication is that the (index) item does not have to be tested for every batch of product, but the manufacturer should ensure that the item is met in the manufactured product.