รายละเอียดเอกสาร

The alkalinity of crude glycerine is expressed in terms of Na2O which may be present in any of the following forms: 1. Free caustic alkalinity (NaOH); 2. Carbonate alkalinity (Na2CO3 and/or NaHCO3); 3. Alkalinity combined with or equivalent to organic acids or esters (RCOONa). The acidity of crude glycerine is likewise expressed in terms of the Na2O equivalent to the free acids present. Organic acids may be free or, in acid crudes they may be esterified with the glycerin. In the latter form they cannot be determined by direct titration. The analytical procedure to follow, therefore, depends upon the reaction of the sample to phenolphthalein indicator soln., after dilution with several volumes of distilled water. Applicable to crude glycerine of salt, saponification or hydrolyzed types.