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Is screw cap or crimp cap of headspace vial right for you(2)?
Dec. 31st, 2019
By calculating the percentage of relative loss within 6 hours, the average compound area from T0 to T6 is compared. The relative percentage difference for each Headspace vial is shown in below.
As we can be seen from the picture, the 18mm 20ml screw headspace vial cap’s seal from T0 to T6 are not as good as the 20mm 20ml crimp headspace vial cap. It is also worth that in six hours screw cap and crimp cap had very little change in ISTD.
After looking at the data and taking everything into account, I think if you do Headspace analysis of highly volatile compounds (gases) in the lab, you should use crimp headspace vial. However, even with use of crimp headspace vials, we still need to be aware of the fact that lighter, more volatile compounds, can still escape the Headspace vial.
Now, having said that, I don't want to give the impression that screw caps are worthless. Screw top Headspace vial can certainly be used for Headspace analysis, especially if the compound being analyzed is less volatile, or if it takes you 3-5 minutes to prepare sample to analysis. For many customers analyzing the standard list of solvents and volatiles a screw cap may be appropriate. Please choose the suit 20ml headspace vial in your experiment.