Sodium stearate is the sodium salt of stearic acid. This white solid is the most common soap. It is found in many types of solid deodorants, rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.
Fine, white powder, soapy to the touch, usually having a slight, tallow-like odor. Is affected by light. Its solutions are alkaline to phenolphthalein TS.
Slightly soluble in water and in alcohol (96 percent).
(A) Freezing point : minimum 53 °C
(B) Acid value : 195 to 210
(C) By Gas Chromatography
(D) Reaction (b) of sodium
(E) Intensely yellow color produced to non-luminous flame
(A), (B) & (D) BP/EP (C) BP/EP/USP (E) USP
Acidity Or Alkalinity
(A) Not less than 0.60 ml and not more than 0.85 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator.
(B) Between 1.00 ml and 4.25 ml of 0.020 N sodium hydroxide is required. (Between 0.28% and 1.2% as stearic acid).
(A) BP/EP (B) USP
Alcohol Insoluble Substances
It dissolves completely, and the resulting solution is clear or not more than slightly opalescent.
Maximum 0.2 % w/w.
Maximum 0.3 % w/w.
Maximum 5 ppm. (Atomic absorption spectrometry)
Loss On Drying
Maximum 5.0 % w/w, dry the residue at 105 °C for 4 h.
(A) Total aerobic microbial count : NMT 1000 cfu/g.
(B) Total yeast and mould count : NMT 100 cfu/g
(C) Escherichia col & salmonella : Should be absent.
Fat & Fatty Acids (Acid Value) (Iodine Value)
(A) Between 196 and 211.
(B) Not more than 4.0
(A) Sodium (By GC)
(B) Stearic Acid
(C) Sum Of Stearic Acid & Palmitic Acid
(A) Between 7.4% w/w to 8.5% w/w, dried substance.
(B) Minimum 40% w/w.
(C) Minimum 90% w/w.