Silica gel aluminium plates, (F 254, 20 cm × 20 cm), were obtained from Merck Darmstadt Germany. A model of gas chromatography-mass spectrometer (Varian CP-3800 GC equipped with Saturn 2200 MS detector) with a VF -1MS capillary column (30 mm × 0.25 mm × 0.25 μm) was used.