Hi Every body

I want to detect Peroxide value. I use this method:

Procedure The sample has to be protected from the air, stored in a cool place and should not be opened before the onset of the determination. Other tests have to be carried out afterwards. Solid fats may not be melted before the determination. - Transfer approx. 3 g of the sample, accurately weighed, taken from the centre of the sample (attention must be paid to the fact that no sample is taken from the surface) into a 250 mL Erlenmeyer flask closed immediately with glass stopper. - Add 50 mL of the appropriate solvent mixture (I, II or III, part 3.2.4) - Add 1mL of saturated potassium iodide solution, freshly prepared, and allow reacting for 60 seconds ± 1 second while agitating manually but vigorously the solution at least twice. - Add 100mL of water and shake. - Titrate with the appropriate sodium thiosulfate solution (0.01 or 0.1 mol/L, part 3.2.3), using 1 mL starch solution or 0.1 g of Thyodene indicator from a purple to a slight yellow or colourless endpoint The indicator should be added towards the end of the titration but while the pale straw colour is still present. During titration shake until the blue colour disappears. Carry out a blank titration under the same conditions. No more than 0.5 mL of sodium thiosulfate solution should be consumed for this purpose. If this volume is exceeded, it is necessary to re-examine the quality of the reagents.

But about product that has dark color I can't define color change.

please introduce a method by HPLC.