Polyamidoamine dendrimer–digoxin impregnated PVC film in the fingerprint detection of herbs’ essential oil coupled to gas chromatography–mass spectrometry

Third-generation polyamidoamine (G3 PAMAM) dendrimer–digoxin (PAMAM-Dig) is prepared, and conjugation is confirmed by 1H-NMR, Fourier transform infrared spectroscopy (FT-IR), and thermal analysis. Then, PAMAM-Dig impregnated polyvinyl chloride (PAMAM-Dig/PVC) film has been prepared by mixing PAMAM-Dig, PVC powder, and 2-nitrophenyl octyl ether (O-NPOE) as the plasticizer in tetrahydrofuran. Differential scanning calorimetry (DSC) evaluation shows the as-prepared film is thermally stable below 200 °C. The film is mounted above the powder as well as the essential oil of Thymus vulgaris. The Taguchi orthogonal array is used to optimize the experimental conditions for adsorption of volatile constituents. At optimized conditions, the obtained fingerprint was the same or better than static headspace sampling of the essential oil. The chromatogram pattern had also obtained by floating the fiber in the essential oil, and more components have observed. Film-to-film variations were less than 10%. All obtained patterns are compared with those of different solvent extracts of Thymus vulgaris. It is concluded that PAMAM-Dig/PVC film could apply for fingerprint analysis of herbs’ volatile and semi-volatile constituents with no need for prior extraction.