Raw Material Identity, Assay and Impurities

Appearance

A visual examination of the material or product against the description in its monograph or specification, such as physical form, color, odor where stated, and clarity. It is usually the first check made on a sample. The report states whether the sample conforms to the description and records what was observed; it is a conformity statement, not a measured value.

Raw material identification

Identification answers whether the material is the substance named. Monograph identification tests compare the sample with a reference standard or a defined characteristic, for example a spectrum, the retention time of the main peak in a chromatographic test, or a specific chemical reaction. Each test is reported as conforming or not conforming. Which tests apply depends on the material; tell us the document, and we use the current official edition unless you name another applicable one.

Raw material assay

An assay measures how much of the named substance the material contains. It is measured by the procedure the monograph or specification names, which may be chromatographic, titrimetric or spectroscopic depending on the substance, with comparison against a reference standard where the selected procedure uses one. The result is usually reported as a percentage on the basis the document states, such as the dried or anhydrous substance, and compared with its acceptance range.

Raw material organic and inorganic impurities

Organic impurities, such as related substances, degradation products and residual starting materials, are usually measured by a chromatographic procedure that separates them from the main substance; each named impurity and the total are reported against the limits in the monograph or specification. Inorganic impurities are assessed by tests such as residue on ignition and elemental impurities, described on the Elements and residue page.