The acid value IA is the number that expresses, in milligrams the quantity of potassium hydroxide required to neutralise the free acids present in 1 g of the substance.
The ester value IE is the number that expresses in milligrams the quantity of potassium hydroxide required to saponify the esters present in 1 g of the substance. It is calculated from the saponification value IS and the acid value IA.
The hydroxyl value IOH is the number that expresses in milligrams the quantity of potassium hydroxide required to neutralise the acid combined by acylation in 1 g of the substance.
The iodine value II is the number that expresses in grams the quantity of halogen, calculated as iodine, that can be fixed in the prescribed conditions by 100 g of the substance.
The peroxide value IP is the number that expresses in milliequivalents of active oxygen the quantity of peroxide contained in 1000 g of the substance.
The saponification value IS is the number that expresses in milligrams the quantity of potassium hydroxide required to neutralise the free acids and to saponify the esters present in 1 g of the substance.
The term “unsaponifiable matter” is applied to the substances non-volatile at 100-105 °C obtained by extraction with an organic solvent from the substance to be examined after it has been saponified.
Semi-micro determination of water is based on the quantitative reaction of water with a reagent containing sulphur dioxide and iodine in a suitable anhydrous medium in the presence of a base with sufficient buffer capacity.
The coulometric titration of water is based on the quantitative reaction of water with sulfur dioxide and iodine in an anhydrous medium in the presence of a base with sufficient buffer capacity. In contrast to the method described under Ph.Eur. 2.5.12, the iodine is formed electrochemically by oxidation of iodide in a reaction cell. The iodine formed at the anode immediately reacts with water and sulphur dioxide contained in the reaction cell. The amount of water in the substance is directly proportional to the amount of electricity to the end point of the titration. When all the water in the cell is used up, the end point is reached and an excess of iodine is produced.
The content of essential oil in drugs is determined in a special apparatus by steam distillation. The distillate is collected in a measuring tube containing xylene to absorb the essential oil, while the water automatically returns to the distillation flask.