The invention relates to an ion mobility spectrometer which has at least a first drift chamber and a first switchable ion gate for the controlled transfer of ions into the first drift chamber, wherein:—the first ion gate is designed as a field switching ion gate having at least a first counter electrode and a first injection electrode; wherein—a first ionization chamber is formed between the first counter electrode and the first injection electrode, into which first ionization chamber ions to be analyzed by ion mobility spectrometry can be fed from an ionization source. The invention also relates to an ion mobility spectrometer which has at least a first drift chamber and a first switchable ion gate for the controlled transfer of ions into the first drift chamber and a second drift chamber separated from the first drift chamber and a second switchable ion gate for the controlled transfer of ions into the second drift chamber. The invention also relates to a method for analyzing samples by ion mobility spectrometry by means of an ion mobility spectrometer, e.g. an ion mobility spectrometer of the type mentioned above, wherein by means of an ionization source ions to be analyzed arc produced from the sample and are provided in an ionization chamber of the ion mobility spectrometer.