High-performance liquid chromatography of unmodified rosin and its applications in contact dermatology

Rosin is a well recognised skin sensitiser and is also amongst the most common causes of occupational asthma. Due to its complex chemical composition, it is difficult to isolate its many components and this has hindered progress in the identification of the specific respiratory and contact allergens it contains. This paper reports the application of high-performance liquid chromatography and other analytical techniques to the isolation and identification of contact allergens in complex mixtures such as rosin. HPLC methods were developed in order to isolate as many rosin components as possible and these were then patch tested on rosin sensitive individuals. The structure of the most dermatologically active component was then determined using mass spectrometry, nuclear magnetic resonance and infrared techniques. An HPLC method has also been developed which will enable the identification of rosin in commercial products, providing a valuable tool for determining the cause of rosin contact allergy. Furthermore, mass spectral data for the common abieitic-type resin acids are compiled which were used to confirm the identification of the HPLC resin acid peaks and have not been reported previously.