Conjugated diene value (CDV)
The AOCS official method (Ti 1a-64) was used to determine CDV (AOCS,
2017). In brief, approximately 10 mg oil samples were dissolved in 10 ml
isooctane, and the solution (1.0
ml) was diluted with 9 ml isooctane. The solution was added in a quartz
cuvette, and the absorbance was measured with the same spectrophotometer
used for PV at 233 nm. The average values of two measurements are
reported. The CDV was calculated by the following equation:
\begin{equation}
CDV=0.84\times[\left(\frac{A_{s}}{b\times c}\right)-k_{o}]\nonumber \\
\end{equation}As: observed absorbance at 233 nm of the sample,b: cuvette length in cm, c: concentration of the sample in
g/L, Ko: absorptivity by acid or ester groups.