"HG/T 5252-2017 Spinning & weaving dyeing and finishing aids, Determination of dihydrogenated tallow-based dimethylammonium chloride" specifies a method for the determination of dihydrogenated tallow-based dimethylammonium chloride (DHTDMAC) residues in Spinning & weaving dyeing and finishing aids by liquid chromatograph Tandom mass spectrometer (LC-MS/MS). DHTDMAC is usually composed of two alkyl dimethylammonium chloride mixtures with a carbon chain length of 10~ 20. This standard applies to the determination of DHTDMAC in Spinning & weaving dyeing and finishing aids. The standard extracts DHTDMAC from samples by acidifying methanol, extracts it in an ultrasonic bath, and then uses LC-MS/MS instrument to determine its main components. The external standard method is used for quantitative analysis. In order to ensure the accuracy of the determination, the standard requires the use of analytically pure reagents and first-class water that meets the GB/T 6682 standard.