Is screw cap or crimp cap of headspace vial right for you?

Is screw cap or crimp cap of headspace vial right for you?

Dec. 31st, 2019
In headspace GC analysis, we can find that there are screw cap headspace vial and crimp cap headspace vial. But which one is right for your experiment? When you do residual solvents analysis. This article may not only help you choice headspace vial cap, but also help laboratory technician who analysis other matrices looking for residual solvents or very volatile sample.

headspace vial experiment

This is referring to the screw-thread caps (18 mm) and crimp caps (20 mm) for 20 mL headspace vials. We don’t just recommend screw cap headspace vial or crimp cap headspace vial by “feel” or price, running a little experiment to compare the performance of the two kind of headspace vial caps. The experiment was designed to analyze a few very volatile sample and gather data to prevent which type cap of headspace vial is better. Please look at the products, firstly.

 20ml headspace vial


Sample preparation included adding propane, butane, and isobutane standards in N, NDMA along with α, α-Trifluorotoluene as the ISTD to a 20ml headspace vial. To model the headspace vial cap’s ability to keep these volatile compounds from escaping the vial, time study was designed. In this study, 14 samples were prepared for each vial type and the samples were split into two sets of 7. Set one (T0) was run immediately after the samples were prepared and set two (T6) was run 6 hours later. It should also be noted that the crimp cap pressure was set to model the tightness of a screw cap. This meaning that the amount of torque needed to remove a screw cap was similar to that of the torque needed to spin a crimped, crimp cap.

Next article will give you the experimental result, you will get the answer which one is the right headspace vial for you. Please follow us.