Date of Award

Summer 1982

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Pollard, Bruce D.

Second Advisor

Hoffman, Norman E.

Third Advisor

Nakamoto, Kazuo

Abstract

The development of an automated method for determining the iodine number for various industrial fatty acids is reported. The method is based on flow injection techniques using a Fiatron SHS-200 system for pump and injector. The chemistry is a modified version of the standard ~Jij s solution method in which a fatty acid sample dissolved in glacial acetic acid is injected and butt mixed with a carrier solution of iodine monochloride ("ICl) also in glacial acetic acid. As the solution travels through a reaction coil, the halogen adds across double bonds in unsaturated fatty acids resulting in a reduction in the ICl concentration proportional to the iodine number of the fatty acid sample. Optimization of the method is discussed. The parameters optimized were: injection volume (0.5 mL), flow rate (1.6 mL/min ), reaction temperature (25°C), reaction coil length ( 6 m) and ICl concentration ( 0.045 M). The possible use of a catalyst was investigated and rejected. Two detection systems compared were UV-Visible absorption at 360 nm and potentiometric sensing using platinum sensing and iodide selective reference electrodes in a special flow through cell. The system was fully computerized using an Aim-65 microcomputer which manipulated the data from all experiments. A blind field test using actual industrial samples gave satisfactory results within 6% deviation from the accepted iodine number. In comparing the results of the FIA method with those of the standard Wijs method, it was found that FIA method was simple--only one reagent, ICl, needed, fast--80 samples per hour sampling rate and economical-only 1.2 mL ICl solution needed for one determination. The standard Wijs method was tedious having many reagent preparations and titrations, slow--4 samples per hour sampling rate and uneconomical too much reagent consumed.

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