Development and Validation of a Differential Scanning Calorimetry Purity Determination Method for Polycyclic Aromatic Hydrocarbons

Abstract

Based on the standard test method for purity by differential scanning calorimetry, ASTM E 928, a robust differential scanning calorimetry purity determination method for highly pure polycyclic aromatic hydrocarbons (PAHs) has been developed and validated. The robustness of the developed method was investigated by determining, under varying measurement conditions, the purity of two PAH certified reference materials (CRMs), benzo(c)phenanthrene and dibenzo(a, h)anthracene. The repeatability and intermediate precision of the developed method was then determined by analysing the purity of benzo(c)phenanthrene and dibenzo(a, h)anthracene and PAH candidate CRMs indeno (1, 2, 3-c, d)pyrene, 6-methylchrysene and benzo(a)pyrene during a validation study. The trueness of the method was studied using the same (candidate) CRMs and a series of 41 other PAH CRMs. For each of the five (candidate) CRMs, an individual relative expanded measurement uncertainty was estimated. For the PAH-family of materials for which the DSC purity determination method has not been validated, relative expanded measurement uncertainties of 0.72 % and 0.75 % were estimated, respectively for materials that have to be melted only once and materials that have to be melted twice before a stable melting peak is obtained.