This standard specifies the Potentiometric titration, poten-tiometry method for the determination of hydrogen sulfide and mercaptan content in liquid hydrocarbons. It is suitable for the determination of hydrogen sulfide and mercaptan content in liquid hydrocarbons such as gasoline, naphtha, light circulating oil, and crude oil. The detection limit is 0.2 μg/g for mercaptan (sulfur) and 1.0 μg/g for hydrogen sulfide (sulfur). The method summary involves dissolving the sample in an Isopropanol solvent containing a small amount of ammonia, performing Potentiometric titration, poten-tiometry with silver nitrate (AgNO3) Isopropanol standard solution, and using Glass electrode as reference electrode, silver - silver sulfide electrode as indicator electrode. Both reagents and materials need to be of analytical purity level.