²H/¹H ratio analysis of flavor compounds by on‐line gas chromatography–pyrolysis–isotope ratio mass spectrometry (HRGC–P–IRMS): citral

Based on 2 H/ 1 H measurements of commercial synthetic and natural citral (neral and geranial), on‐line gas chromatography–pyrolysis–isotope ratio mass spectrometry (HRGC–P–IRMS) was used to determine the δ 2 H SMOW values of citral in essential oils from Cymbopogon flexuosus and C. citratus , Litsea cubeba , Lippia citriodora , Melissa officinalis and the Citrus species C. aurantium, C. limon , C. sinensis, C. paradisi and C. aurantifolia . The technique allowed reliable differentiation of natural (δ 2 H SMOW from −236 to −314‰) from synthetic products (δ 2 H SMOW from +38 to −197‰), even when some samples can also have very negative δ 2 H values, e.g. −197‰, but permitted no distinction within the origins from the various plant species.