Mass concentration means mass per unit volume and is used in the construction mass_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as 'nitrogen' or a phrase such as 'nox_expressed_as_nitrogen'. The chmical formula for tetrabromo-o-chlorotoluene is C7H3Br4Cl. It is a member of the group of halogenated organics and aromatics. The IUPAC name is 1,2,3,4-tetrabromo-5-chloro-6-methylbenzene