This method is for determining phenols and hindered phenols inpetroleum fractions up to and including No. 2 distillates; e.g.,gasolines, naphthas, kerosines, jet fuels, No. 1 fuels and No. 2fuels. The procedure gives nicely defined titration curves andendpoints on samples up to No. 1 distillate, but No. 2 oilssometimes give titration curves with ill-defined endpoints. Thereis no way to predict this behavior, so the analyst must simply tryit on the sample.

Phenols as hindered as butylhydroxytoluene (BHT) can be titrateddirectly using this method. Provision is included to overcome theacidity of mercaptans and thiophenols via a mild oxidation to thecorresponding disulfides.

This method overlaps UOP Method 262, PHENOLS AND THIOPHENOLSIN PETROLEUM PRODUCTS BY SPECTROPHOTOMETRY, which can be usedwith accuracy on gasolines and on refinery caustic solutions.