GB/T 23973-2009 is a standard for the determination of formaldehyde content in dyestuff products. It specifies the equipment required for the experiment, such as spectrophotometer, etc., and describes the preparation method of the reagent. For dyestuff samples, the standard specifies the pretreatment process, including the extraction of the sample and other steps. Through a specific chemical reaction to make formaldehyde color, and then use the instrument to measure Absorbance, and then accurately calculate the formaldehyde content in dyestuff products. The standard provides a reliable detection method for dyestuff manufacturers to control the mass of products and protect the health of consumers, and effectively promotes the green and standardized development of the dyestuff industry.