White Papers and Scientific Reviews

Substance characterisation is an analytical process through which the chemical identity and composition of a substance may be demonstrated.

Characterisation presents evidence that the substance manufactured or imported by the registrant is the same as the substance being described in the registration dossier. A substance may be classified as: Well-defined - Has a defined qualitative and quantitative composition or UVCB - Substance of unknown or variable composition

Although there is no precise definition of an 'organic substance', all organic substances will contain carbon in their molecular formula. This document describes the analytical methodology appropriate for the characterisation of a well-defined organic substance.

Mono- and multi-constituent inorganic substances are regarded as having a welldefined composition.

Arguably, the characterisation of inorganic substances, whether mono- or multiconstituent, relies to a greater extent on non-spectroscopic analytical techniques than does the characterisation of organic substances. Elemental analysis, determination of the ionic content, degree of hydration and crystal morphology are often particularly important. Regardless of whatever suite of tests is selected, the combined results obtained must demonstrate unequivocally the identity and purity profile of the substance in question.

Substances of Unknown or Variable composition, Complex reaction products or Biological materials (UVCB) are substances in which: The number of constituents is relatively large and/or The composition is, to a significant extent, unknown and/or The variability of composition is relatively large or poorly predictable.

By their very nature, UVCB substances can present a difficult analytical challenge and their characterization demands a somewhat different approach to that used for well-defined (mono- and multi-constituent) substances. Typical examples of UVCBs include petroleum products, plant-derived essential oils and complex inorganic species such as minerals.