Kvasný průmysl (Sep 2000)
Determination of hop oils using the solid-phase microextraction method (SPME).
Abstract
The method of solid-phase microextraction in the "headspace" execution (HS-SPME) was used for the insulation of hop oils from the hop cones of female plants and from the inflorescences of male plants. Several SPME fibres with different polarity of the active layer (PDMS 100 mm and 30 mm, PDMS/DVB 65 mm, PA 85 mm) were tested under various experimental conditions (temperature, exposure time, samples weighed-out). The sorption of the analyses has been vigorously influenced by the temperature and the exposure time, while the sample weighed-out in the range of 0,1 to 0,3 g has not basically influenced the sorption of the individual oil components. From the tested SPME fibres the most suitable one proved to be the PDMS/DVB 65 mm fibre, for the analyses both of cones and of male plants flowers. The sorption intensity on the PDMS/DVB 65 mm fibre was twice to six times higher in comparison with the other ones. The optimum results on all fibres were achieved with the sample weight-out of 0,2 g, the exposure temperature of 50 °C in a two-hours period. The composition of hop oils insulated by the HS-SPME method and by the standard destilation one showed a very good conformity. Due to the fact that only one cone is sufficient for the oil insulation by the SPME method, is this procedure advantegenous mainly in cases when a sufficient quantity of sample for insulation by the alternative method is not at disposal.The method of solid-phase microextraction in the "headspace" execution (HS-SPME) was used for the insulation of hop oils from the hop cones of female plants and from the inflorescences of male plants. Several SPME fibres with different polarity of the active layer (PDMS 100 mm and 30 mm, PDMS/DVB 65 mm, PA 85 mm) were tested under various experimental conditions (temperature, exposure time, samples weighed-out). The sorption of the analyses has been vigorously influenced by the temperature and the exposure time, while the sample weighed-out in the range of 0,1 to 0,3 g has not basically influenced the sorption of the individual oil components. From the tested SPME fibres the most suitable one proved to be the PDMS/DVB 65 mm fibre, for the analyses both of cones and of male plants flowers. The sorption intensity on the PDMS/DVB 65 mm fibre was twice to six times higher in comparison with the other ones. The optimum results on all fibres were achieved with the sample weight-out of 0,2 g, the exposure temperature of 50 °C in a two-hours period. The composition of hop oils insulated by the HS-SPME method and by the standard destilation one showed a very good conformity. Due to the fact that only one cone is sufficient for the oil insulation by the SPME method, is this procedure advantegenous mainly in cases when a sufficient quantity of sample for insulation by the alternative method is not at disposal.
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