2.7. Peroxide value (PV) Measurement
Peroxide value is a measure of peroxides contained in the oil.
PV is determined by measuring iodine released from potassium
iodide.
A known measured weight of oil samples is dissolved in
acetic acid then chloroform and saturated KI mixture are
added to the sample and the amount of iodine liberated from
KI by the oxidative action of peroxides present in the oil is
determined by titration with standard sodium thiosulphate
using starch solution as an indicator. Titration was also
performed for blanks.
PVðmeq=kg oilÞ ¼ ðS BÞ W N ð2Þ
where B is the volume of sodium thiosulphate used for blank,
W is the weight of sample, S is the volume of sodium thiosulphate
consumed by the sample oil and N is the normality of
standard sodium thiosulphate (AOAC, 1984).