Determination of terpenoid contents of aromatic plants using NIRS.

The method was developed in order to provide a fast, simple and non-destructive analysis of terpenoid compounds of aromatic plants. For this purpose, spectroscopic data were collected on the surface of dried plant samples by using near infrared spectroscopic (NIRS) analysis. Volatile substances were extracted from aromatic plants using hydro-distillation method to determine terpenoid composition by using gas chromatography-mass spectrometry (GC-MS). Multivariate calibration methods namely, partial least squares (PLS) regression, were used for data analysis. The correlation between NIRS spectral data and the concentrations of terpenoid contents were established with coefficient of determination (R2 ) values in the range of 0.953-0.997. The model validation results showed that the contents of 24 terpenoids were predicted accurately with a satisfactory limit of detection (LOD) values. In this study, 24 terpenoids, the major constituents of volatile compounds, from nine aromatic plants were investigated.