By measuring adjusted retention times of an analyte itself and of two benchmark n-alkanes
and with the numbers of carbon atoms n and
n + 1, respectively, we calculated the Kovats retention
index I, characterizing the retention of the analyte on
the studied stationary phase at the temperature t (°C),
using the equation [13]
, (2)
provided that the condition ≤ ≤
was met. The adjusted retention time of an analyte was
calculated as a difference between the measured retention time of the analyte and the retention time of an
unadsorbed component, methane, which was injected
into the column together with the studied adsorbent.