The analysis of potential light-induced H₂ production is conducted ex situ by sampling the headspace of the photoreactor using a gas-tight needle and analyzing the gas composition using gas chromatography (GC). For this purpose, it is important that the photoreactor is equipped with a septum that can be pierced for gas sampling. This can be accomplished by using a GL14 Schlenk photoreactor, combined with a GL14 septum cap. Photocatalytic experiments for H2 detection can also be carried out in simple GC vials, although in this case the vial needs to be prepared in a glovebox to allow for exclusion of oxygen.