retenƟon t ime
n-pentadecane
(15.3 min – index 1500)
Unknown compound
(16.2 min, unknow index)
n-hexadecane
(17.1 min, index 1600)
A graphic interpretation of the retention behavior is illustrated here:
log (retenƟon Ɵme)
retenƟon index
1600
1500
n-hexadecane
n-pentadecane
unknown
substance
However, applying the logarithmic interpolation given by equation given in
Fig. 4.11 results in:
= 1500 + 100
log 16.2 − log 15.3
log 17.1 − log15.3
or
= 1500 + 100 • 0.5139 ≈ 1551.4
The calculation reveals a Kovats index of approx. 1551 for the unknown
compound.
52
4 Instrumental Analysis