Classification and naming of dyes, stains and fluorochromes.

A classification of dyes and other colorants is proposed, based on the chemical features responsible for their visibility and generally consonant with the writings of modern color chemists. The scheme differs in several respects from that of the Colour Index (CI), but it retains some traditional small groups of dyes that include biological stains. Natural dyes, recognized as a group in the CI, are placed with or near synthetic dyes with identical or similar chromophores. The new scheme also provides categories for dyes and fluorochromes that do not have places in the CI classification. Some CI categories, including lactones, aminoketones and hydroxyketones, are not recognized in this new scheme, which is adopted in the forthcoming 10th edition of Conn's Biological Stains: a Handbook of Dyes and Fluorochromes for Use in Biology and Medicine. Some rules are also set out for the spelling of trivial names, which has long been inconsistent in scientific literature. The ending '-ine' is used for compounds derived from organic bases (e.g., fuchsine and thionine, not fuchsin or thionin), and names ending in '-in' are for compounds that are not bases or their derivatives (e.g., eosin and phloxin, not eosine or phloxine). Initial capital letters are used only for words that are names of people or places (e.g., Nile blue or Congo red) and for the 'generic' components of CI application names (as in Acid yellow 36). Other words, including trade names that have fallen into common usage are not capitalized (e.g., alcian blue, biebrich scarlet, coomassie blue). The recommended spellings of some dyes differ from those commonly seen in vendors' catalogs and in biological publications, but they are generally consistent with English and American dictionaries, with recent writings in English by color chemists, and with the trivial names of other organic compounds.