A simplified technique for analysis by alkali isomerization

Summary Potassium tertiary butoxide (1.1 M, 15.5%) in t‐butanol readily isomerized linoleic and linolenic acids at 60°C. The absorptivity value for linoleic acid during isomerization rose rapidly, then slowly reached a maximum (88.5) after three days. Maximum absorptivity values for linolenic acid at both 233 mμ (68.5) and at 268 mμ (65.0) were attained at 12 hrs.; thereafter absorptivity at both wavelengths decreased with time. Glycerol also reacted with potassium‐t‐butoxide under the experimental conditions to produce an absorption maximum at 267 mμ; however this absorbance was easily destroyed by treatment with hydrochloric acid. A simple procedure has been described for isomerization with the alkoxide in a reagent bottle at 60° for 20 hrs. Analyses for linoleic and linolenic acids in five seed oils isomerized by the “bottle method” agreed well with results obtained by the A.O.C.S. KOH‐glycol method.