Reptile volatilome profiling optimisation: A pathway towards forensic applications

Abstract

• The methods for collection and analysis of reptile volatilomes were optimised to generate reproducible profiles. • Column type influences the detection of trace volatiles, which impacts the specificity and reproducibility of profiles. • Further statistical analysis is required to determine whether the presence or relative abundance of compounds impact the species specificity of volatilomes. Reptiles are the most trafficked live taxa in the illegal wildlife trade, in part due to their popularity as an exotic pet. Current methods used to detect these illegally trafficked animals are limited. This study optimised the collection and analysis parameters associated with volatilome collection that will set the foundation for targeted odourant detection methods. This study determined that the dual sorbent type (Tenax® TA and Carbograph 5DT) in combination with 20-min sampling times and 15-min sampling intervals collected the most reproducible reptile volatilome profiles. It was also determined that desorption methods with mid-range desorption flows (20 ml/min), trap temperatures (-15 °C), and mid-range trap desorption (25 ml/min) were most effective in retrieving collected reptile volatilomes. Two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was used for analysis, where combined Rxi-624 Sil MS (mid-polar) first dimension and Stabilwax® (polar) second dimension column sets were selected as the most effective columns for analysing reptile volatilomes. The resultant data collected and analysed using these parameters demonstrated that individual volatilomes from three reptile species were distinct using principal component analysis. In addition, this work highlighted the need for more rigorous statistical methods to determine reptile biomarkers and which compounds most significantly influence volatilome profiles between species.