QUALITATIVE ANALYSIS OF SURFACE-ACTIVE SUBSTANCES

1. Cation-active surfactants and bromophenol blue form compound with celestial-blue colouring usualy (pH=7) . Quaternary ammonium salt make solvent with greenish colour.
2. If you will add the anion-active surfactant solution to cation-active surfactant solution, that sample will be turbid.
3. Negative result first of two test demonstrate nonionic surfactant presence.  
Cotland and Dumerse proposed very interesting authentication method for surface active agents. This method apply 6 reagents:
1. cerium nitrate;
2. solution of the aluminium chloride in chloroform;
3. bromine water;
4. potassium permanganate;
5. alcoholic solution of the potassium hydroxide;
6. solution mixture of the acetic anhydride and sulfuric acid.

Substances Structural formulas
1
2
3
4
5
6
Sodium stearate (soap) RCOONa
-
-
+
-
+
-
Sodium tallate (liquid soap) RCOONa
-
+
(b)
+
+
+
+
Paraffine sulfates RCH2OSO3Na
-
+
(a)
-
-
-
-
Olefine sulfates RCH2OSO3Na
-
+
(a)
+
+
-
-
Alkylaryl sulfonates RC6H4SO3Na
-
+
-
-
+
-
Ether of the nonsaturated fatty acids and -sulfaethanole RCOOCH2CH2SO3Na
+
+
(a)
+
+
+
-
Alkylphenole sulfoethoxilates RC6H4O(CH2CH2O)nSO4Na
+
+
+
-
+
-
Taurineamide fatty acids RCONHCH2 CH2SO3Na
+
+
(a)
+
+
+
-
Oxyethylated saturated spirits RO(CH2CH2O)nH
+
-
-
-
-
-
Oxyethylated nonsaturated spirits RO(CH2CH2O)nH
+
+
+
+
-
-
Oxyethylated alkylphenols RC6H4O(CH2CH2O)nH
+
+
+
-
-
-
Oxyethylated mercaptans RS(CH2CH2O)nH
+
-
+
+
-
+
-
Oxyethylated fatty acids RCOO(CH2CH2O)nH
+
+
+
+
+
-
Oxyethylated nonsaturated fatty acids RCOO(CH2CH2O)nH
+
+
+
+
+
-
Oxyethylated tallate RCOO(CH2CH2O)nH
+
+
+
+
+
+
Copolymers of the ethylene oxide and propylene [(CH3CHCH2O)x(CH2CH2O)y]nCH3
+
-
+
+
-
-
Sorbitan monolaurates RCOO(sorbitan)
+
-
-
+
+
-
Polyoxyethylene sorbitan laurates RCOO(sorbitan)[(OCH2CH2O)nH]x
+
+
(b)
+
+
+
-
Alkylamides fatty acids RCONHCH2CH2 OH
+
-
+
+
+
-
-
(a) - green colour;
(b) - pink colour.