Determination of alkaloids in capsules, milk and ethanolic extracts of poppy (Papaver somniferum L.) by ATR-FT-IR and FT-Raman spectroscopy

Abstract

Fourier transform (FT) infrared spectroscopy using a diamond composite ATR crystal and NIR-FT-Raman spectroscopy techniques were applied for the simultaneous identification and quantification of the most important alkaloids in poppy capsules. Most of the characteristic Raman signals of the alkaloids can be identified in poppy milk isolated from unripe capsules. But also poppy extracts present specific bands relating clearly to the alkaloid fraction. Raman spectra obtained by excitation with a Nd∶YAG laser at 1064 nm show no disturbing fluorescence effects; therefore the plant tissue can be recorded without any special preparation. The used diamond ATR technique allows to measure very small sample amounts (5–10 µL or 2–5 mg) without the necessity to perform time-consuming pre-treatments. When applying cluster analysis a reliable discrimination of “low-alkaloid” and “high-alkaloid” poppy single-plants can be easily achieved. The examples presented in this study provide clear evidence of the benefits of Raman and ATR-IR spectroscopy in efficient quality control, forensic analysis and high-throughput evaluation of poppy breeding material.