Modulation events were controlled using a low-cost Arduino Uno microcontroller (Ivrea, Italy)
[22–24]. Full hardware setup is presented in Fig. S1. Internal counter used 16-bit hardware on
ATmega328. The basic wiring-program is described in Supplementary Data. Synchronization of
modulation sequence and GC analysis was attained by analogic monitoring of instrument’s remote
control. GC Image (Zoex Corporation – Lincoln, NE, USA) was used for data visualization. In addition,
an illustration of the GC×GC-FID prototype is provided in Fig. S2.