This Gulf standard specifies a general method known as the Karl Fischer method suitable for the determination of free water or water of crystallization in most solid or liquid chemical products, both organic and inorganic. Two methods of titration, depending on whether the end point is detected visually or electrometrically, are specified. The visual method can be used when no electrometric apparatus is available but is applicable only to colourless solutions; it is always a direct titration. The electrometric method, on the other hand, may involve either a direct titration or a back-titration. The electrometric method, whether by direct titration or back-titration, is the more accurate, and for this reason it is recommended.