Info

HP 5830 Chromatograph. Columns: OVI or OV 101, 50 m. Temperature program: 120-170°C, 5°C/min. Injection temp.: 225°C. FID temp.: 250°C. Gas flow: Helium at 1.2 ml/min (120°C) or 1.9 ml/min (30°C). Hydrogen at 1.1 bar and oxygen at 1.7 bar. Attenuation: 4 (up to 7). Paper feed: 1.5 cm/min. Integration with HP Integrator 18850 A.

HP 5830 Chromatograph. Columns: OVI or OV 101, 50 m. Temperature program: 120-170°C, 5°C/min. Injection temp.: 225°C. FID temp.: 250°C. Gas flow: Helium at 1.2 ml/min (120°C) or 1.9 ml/min (30°C). Hydrogen at 1.1 bar and oxygen at 1.7 bar. Attenuation: 4 (up to 7). Paper feed: 1.5 cm/min. Integration with HP Integrator 18850 A.

10.2.7 Headspace Gas Chromatography

Headspace gas chromatography (HSGC) is an elegant method for the analysis of the components of the essential oil with high precision, provided a multiple headspace extraction (MHE) is performed. MHE prevents the matrix from interfering with the analysis. Hiltunen et al. have shown that HSGC is suitable for the analysis of the essential oil and individual volatile active principles of chamomile [39, 40, 41]. Using a DANI-HSS 3850 Automatic Head Space Sampler, very precise results were obtained. The analytes were separated by an OV-1-column with variation of the temperature from 140 to 200°C.

Stuppner and Bauer applied this method to the quantitative determination of the chamomile preparation components in water and ethanol, using an SF 52 column and a temperature range from 130-240°C [144, 145]. The results were influenced by the conditioning time and temperature, but mainly depended on the content of ethanol in the sample. Dilution to 5% ethanol in water guaranteed acceptable results. Compared to conventional GC, HSGC gave almost identical values for (-)-a-bisabolol and its derivatives, whereas values of en-yne-dicycloethers were quite low [145].

10.2.8 High-Pressure Liquid Chromatography

The development of an HPLC separation protocol using a Bondapak C18 column under isocratic and gradient conditions (methanol-water mixtures) did not have advantages compared to published TLC and GC methods [122]. Other investigations also found HPLC a less reasonable "Strategy in Chromatography" [141] for the quantification of components of the essential oil. Nevertheless, HPLC is especially suitable for the separation of isomeric compounds. Azulenes separate very well on a Li-Chrosorb RP 8 column (reversed phase), eluting with methanol-water. This method allows the determination of the purity of isolated azulenes as well as the separation of isomeric azulenes (Figure 10.2) [121].

Was this article helpful?

0 0

Post a comment