The method of plasma electron spectroscopy (PLES) is further developed for the analysis of impurities of organic molecules and ammonia in this work. In particular, for the first time the PLES method was used to detect the hydrocarbons impurities: alkanes (methane) and alkenes (ethylene), as well as their derivatives alcohols (ethanol), radicals, and ammonia. As the energies of the registered characteristic electrons are different for different chemical compounds, an important advantage of the PLES method is the fact that it allows simultaneous (in one measurement) registration of various impurities. This work presents a prototype of a PLES-gas analyzer based on nonlocal plasma of negative glow of a short glow discharge in helium.