Evening!
Been through a proportion of the literature surrounding methane determination in porewater samples using headspace GC-FID determination. However, have come across several methods of obtaining headspace samples - in short- a) headspace induced in a water-filled mini-vial by displacement through the injection of helium (inert gas) or (b)introduction of water to a mini-vial (smaller volume than the total volume of the mini-vial it-self) and thereafter crimped/sealed. Advice on which method is more appriopriate would be greatly appreciated.
Cheers