An RA-915+Mercury Analyzer (Ohio Lumex Co., Russia)with a RP-91C pyrolysis accessory (Lumex, Russia) was used for FPAAS mercury determination in dry nanodiamond samples. RA-915+ is a portable multifunctional atomic absorption spectrometer with Zeeman highfrequency modulation of polarization for background correction [36, 44–46]. RP-91C is intended as an accessory for thermal decomposition of solid samples at 800 °C under air atmosphere and the transformation of bound Hg from ionic to atomic species for subsequent determination with a RA-915+ analyzer. The attested detection limit of this analytical system is 0.5 μg/kg (0.5 ppb) at 200 mg of sample [47]. The analysis time is 3 min per a single determination including sample weighing, combustion, and cooling combustion tube. Typical decomposition time
was about 15–40 s.