ISO 5647:2019 "Determination of titanium dioxide in paper and Cardboard" is a standard published by the international standards organization (ISO) that specifies methods for determining titanium dioxide in paper and Cardboard, particularly for coatings or filled products. The standard includes two methods of determination: Spectrophotometric method, spectrophotometry: Determination of titanium dioxide content by measurement of the Absorbance of the sample solution. Atomic absirption spectroscopy-tometry, AAS: Determination using the characteristic absorption light spectrum produced by titanium dioxide in a flame. Both methods are equally effective, and the appropriate method can be selected according to the experimental conditions and equipment.