Thermal degradation of α-pyrrolidinopentiophenone during injection in gas chromatography/mass spectrometry

Abstract

α-Pyrrolidinopentiophenone (α-PVP) is a popular recreational drug in Japan. This drug easily undergoes thermal decomposition during gas chromatography/mass spectrometry analysis. We evaluated three factors involved in the decomposition, namely the injection method (splitless or split, split ratio), injector temperature, and surface activity on the inlet liner. Splitless injection of α-PVP using a used deactivated split/splitless liner at an injector temperature of 250°C caused thermal decomposition. This decomposition was inhibited by split injection. A higher split ratio resulted in greater prevention. Based on the mass spectrum of deuterated α-PVP, the decomposition product was presumed to be an enamine whose double bond was located in the alkyl chain. Lowering the injection temperature from 250°C to 200°C did not prevent decomposition. New glass liners, both deactivated and non-deactivated, were compared. The use of a new deactivated liner minimized thermal decomposition, even for splitless injection, while the non-deactivated liner generated an increase in the amount of the decomposition product. These results showed that the injection method and the surface activity on the inlet liner were involved in the thermal decomposition of α-PVP.