Determination of alkylnaphthalenes in petroleum fractions by second-derivative ultraviolet spectrophotometry

Abstract

The determination of naphthalene and its alkyl derivatives in aviation turbine fuels (ATF) and other petroleum products is important not only with respect to their performance but also for establishing heart cuts for producing intermediate chemicals for the manufacture of dyes, pesticides and agrochemicals. Normal and second-derivative UV spectra of naphthalenes, biphenyls and other interfering aromatics have been studied with a view to developing a method for determining naphthalene and α- and β-methyl-, dimethyl- and trimethylnaphthalenes. The characteristic signals due to the substituted naphthalenes were identified in terms of second-derivative signals in a number of straight-run and cracked products of varying nature. Working relationships were derived for each of the naphthalenes in terms of their signal amplitudes. The method was tested on a number of straight-run and cracked petroleum products and it was found that the results calculated by the proposed method are in close agreement with those given by the zero-order UV spectrophotometric method.