Saponification value is defined as mg KOH needed to neutralize free acids and saponify esters in 1 g of the test substance. A search of the literature showed that the standard saponification methods of the U.S. Pharma...Saponification value is defined as mg KOH needed to neutralize free acids and saponify esters in 1 g of the test substance. A search of the literature showed that the standard saponification methods of the U.S. Pharmacopeia, alcoholic potassium hydroxide were the only saponification reagent. The sample to investigate is saponified with an excess of ethanolic potassium hydroxide solution. After finished saponification the remaining excess of potassium hydroxide is determined by residual titration under Titrimetry , with aqueous volumetric hydrochloric acid. In this study, a test for saponification value has been successfully determined in carnuba wax. The average result has been found 90.9 mg KOH/g substance and, % RPD was 1.65%. This is in contradistinction to the U.S. Pharmacopeia/National Formulary (USP/ NF) Method.展开更多
Carnuba wax consists chiefly of myricyl cerotate (M<sub>W</sub> 817.4) and small quantities of free cerotic acid (C<sub>26</sub>H<sub>52</sub>O<sub>2</sub>, Mw 396.7) an...Carnuba wax consists chiefly of myricyl cerotate (M<sub>W</sub> 817.4) and small quantities of free cerotic acid (C<sub>26</sub>H<sub>52</sub>O<sub>2</sub>, Mw 396.7) and myricyl alcohol (C<sub>30</sub>H<sub>62</sub>O, mp 90°C). Of the two common extraction solvents, ethyl ether or petroleum ether, Lewkowitsch prefers the former. Concerning separation of phases, he advocates addition of small amounts of alcohol or caustic, and he also states that formation of a flocculant layer between the aqueous layer and the solvent does not interfere with the correct estimation of the unsaponifiable matter. These statements were not corroborated in the hands of this chemist. The “Unsaponifiable Matter” in oils or and fats, which consist mainly of hydrocarbons, sterols and aliphatic alcohols of high molecular mass that are not saponifiable by alkali hydroxides but are soluble in the ordinary fat solvents, and to products of saponification that are soluble in such solvents. Carnuba wax, a rather expensive wax, may be adulterated with less expensive paraffin by dishonest merchants. ASTM has a method for determining paraffinic material in carnuba wax. It uses heptanes at its boiling point to dissolve the wax, apply it to a silica gel column, and elute only the nonpolar (i.e. alkane) material. The method has the disadvantage of using a large volume of haptane, nor is it called for by either US Pharmacopeia/National Formulary (USP/NF) or Food Chemicals Codex (FCC). The test for unsaponifiable matter on pure carnuba wax will yield a result of 50.0% - 55.0%, while a higher result will betray the presence of paraffin adulterants.展开更多
文摘Saponification value is defined as mg KOH needed to neutralize free acids and saponify esters in 1 g of the test substance. A search of the literature showed that the standard saponification methods of the U.S. Pharmacopeia, alcoholic potassium hydroxide were the only saponification reagent. The sample to investigate is saponified with an excess of ethanolic potassium hydroxide solution. After finished saponification the remaining excess of potassium hydroxide is determined by residual titration under Titrimetry , with aqueous volumetric hydrochloric acid. In this study, a test for saponification value has been successfully determined in carnuba wax. The average result has been found 90.9 mg KOH/g substance and, % RPD was 1.65%. This is in contradistinction to the U.S. Pharmacopeia/National Formulary (USP/ NF) Method.
文摘Carnuba wax consists chiefly of myricyl cerotate (M<sub>W</sub> 817.4) and small quantities of free cerotic acid (C<sub>26</sub>H<sub>52</sub>O<sub>2</sub>, Mw 396.7) and myricyl alcohol (C<sub>30</sub>H<sub>62</sub>O, mp 90°C). Of the two common extraction solvents, ethyl ether or petroleum ether, Lewkowitsch prefers the former. Concerning separation of phases, he advocates addition of small amounts of alcohol or caustic, and he also states that formation of a flocculant layer between the aqueous layer and the solvent does not interfere with the correct estimation of the unsaponifiable matter. These statements were not corroborated in the hands of this chemist. The “Unsaponifiable Matter” in oils or and fats, which consist mainly of hydrocarbons, sterols and aliphatic alcohols of high molecular mass that are not saponifiable by alkali hydroxides but are soluble in the ordinary fat solvents, and to products of saponification that are soluble in such solvents. Carnuba wax, a rather expensive wax, may be adulterated with less expensive paraffin by dishonest merchants. ASTM has a method for determining paraffinic material in carnuba wax. It uses heptanes at its boiling point to dissolve the wax, apply it to a silica gel column, and elute only the nonpolar (i.e. alkane) material. The method has the disadvantage of using a large volume of haptane, nor is it called for by either US Pharmacopeia/National Formulary (USP/NF) or Food Chemicals Codex (FCC). The test for unsaponifiable matter on pure carnuba wax will yield a result of 50.0% - 55.0%, while a higher result will betray the presence of paraffin adulterants.
