Iodine Value Analysis

The American Oil Chemists' Society (AOCS) recommends the use of ASTM method D1959-97, also known as the Wijs method, for determination of IV. The method involves the addition of Wijs solution to the sample, after which it is allowed to stand in the dark. The reaction is complete after approximately 30 min, at which time potassium iodide is added. The liberated iodine is then titrated with sodium thiosulfate, using a standard starch solution as the indicator.

The traditional AOCS analysis takes at least 30 minutes and has to be performed on samples pulled out of the process line. Near infrared (NIR) spectroscopy, on the other hand, is fast (analysis time of the order of less than 1 minute) and does not require the use of any solvents or reagents. The NIR analysis can be extended to process monitoring with the use of fiber optic probes. This real-time on-line analysis should yield significant savings in time and cost.

Laboratory measurements can be performed using the new AOCS Cd1e-01 method, using Bruker Optics FT-NIR spectrometers with 8 mm disposable vials. The oils and fats of various types used to generate the calibration model. The range of IV is between 0 and 185. A dedicated user interface was developed to acquire and analyze samples using the Bruker Optics OPUS software package and the quantitative analysis model. The prediction result is automatically output to a spreadsheet for the QC lab record. If desired, electronic signature and other 21 CFR 11 requirements are available for the reports.