Top-down thermal analysis versus bottom-up gas chromatography–mass spectrometry in an adulteration study of Pistacia atlantica Desf. oleoresin

Abstract

Pistacia atlantica Desf. oleoresin is one of the most valuable economical exudates in Iran’s western natural forests. Adulteration of this oleoresin with other plant exudates of lower commercial value decreases the quality of end products. Two different methods can be used for adulteration detection: a top-down method, using thermal analysis techniques according to total characteristic investigation of samples, and a bottom-up method based on gas chromatography–mass spectrometry (GC–MS) techniques for compound determination. The volatile components of genuine and adulterated samples were obtained by the hydro-distillation method and analysed using GC–FID and GC–MS. Studying the volatile components indicated qualitative and quantitative differences between raw materials of various qualities; the most predominant was α-pinene. Moreover, carbohydrate compounds as sample components were analysed. The alditol acetate derivatives of extracted gum were prepared and identified using GC–MS. Identification of alditol acetate derivatives of extracted gum revealed the presence of glucose, galactose, xylose, rhamnose, mannose and arabinose in genuine oleoresin. The presence of adulterants can significantly change the carbohydrate concentration (>5 %). Moreover, the total characteristic patterns of raw materials and end products of P. atlantica Desf. oleoresin were monitored by thermogravimetry/differential thermal analysis. The results showed significant variations in the thermal behaviour of genuine and adulterated samples, so it can be introduced as a rapid, cheap and accurate marker for adulteration detection in P. atlantica Desf. oleoresin and is preferable to GC–MS analysis.