2.8. Molecular content of the exhumed nauplii: FT-IR spectroscopy.
The exhumed carcasses were tested for the molecular content in a Fourier-transform infrared (FT-IR) spectrometer Vertex 70 (Bruker Optik GmbH) with a GladiATR attenuated total reflection (ATR) attachment with a diamond crystal (Pike Technologies). The range of spectra registration was 6000–350 cm–1 with the resolution 2 cm–1, number of scans — 256. 10-15 carcasses were rinsed in distilled water and then transferred on the crystal and dried directly on it. The spectrum was registered after complete drying. Sediment particles from the experimental tubes (Artemia with kaolinite, montmorillonite, silica, clinochlore and chamosite) were also washed in distilled water and dried in the same way as the carcasses; their spectra were compared with the corresponding carcasses. We also compared the spectra of the carcasses from the sediments, from sediment-free control, and freshly killed nauplii prepared in the same way. To estimate the initial adherence of sediment particles to the nauplii, we used freshly killed nauplii incubated in kaolinite for 1 day and then rinsed and dried. To investigate the difference between well and poorly preserved carcasses, we applied differential FT-IR testing to the representatives of preservational groups 1-2 and 5 from kaolinite.