1.1 Reagents and solutions
a. Anhydrous Ethanol: Analytically pure
b. Calcium Carbonate: Analytically pure
c. Fluorescent Yellow Ethanol solution: 1g/L
d. Silver Nitrate standard solution: c(AgNO3) = 0.1mol/L
1.2 Analysis Steps
Weigh 0.35g (accurate to 0.0002g) sample into 50mL Ethanol, add 25mL pure water, 0.1g Calcium Carbonate and 8 drops Fluorescent Yellow Ethanol solution. Titrate by 0.1mol/L AgNO3 standard solution. The solution turn to pink red, as the titration end point.
1.3 Result calculation
Calculate the Assay X of Hexadecyltrimethylammonium Chloride in sample according to following formula:
X％＝
V * c * 320
m * 10
In formula:
V: The consumed volume of Silver Nitrate standard solution in titration, mL;
c: Molar concentration of Silver Nitrate standard solution, mol/L;
m: Mass of measured sample, g;
320 - molar mass of Hexadecyltrimethyl ammonium Chloride
1.4 Allowable difference
The difference between the two parallel determination results should not exceed 0.5%, taking the arithmetic mean as the determination result.
