Assembled screw cap with hole and PTFE/silicone septum may be used to minimise the risk of explosion of diazomethane, during preparation of diazomethane for gas chromatographic analysis. It was also used to seal off the heat treated samples, during determination of sugar-amino acid reaction mechanisms using an automated solid-phase microextraction-gas chromatography-mass selective detection (AutoSPME-GC-MSD) approach.