Scott's CEC Technique

for Acid Mucopolysaccharides

Scott and Dorling’s critical electrolyte concentration method for acid mucopolysaccharides.

Molarity of Alcian Blue Solution	MgCl Amount
0.06 M	1.220	g
0.2 M	4.066	g
0.3 M	6.099	g
0.4 M	8.132	g
0.5 M	10.165	g
0.6 M	12.198	g
0.7 M	14.231	g
0.8 M	16.264	g
0.9 M	18.297	g

5µ paraffin sections of neutral buffered formalin fixed tissue are suitable.

Bring sections to water via xylene and ethanol.
Place a section into each alcian blue electrolyte concentration chosen and leave overnight.
Wash with water.
Counterstain with neutral red, if wished.
Dehydrate with ethanols.
Clear with xylene and mount with a resinous medium.

Electrolyte Concentration	Structure	Color
0.06M	All acid mucopolysaccharides	Blue
0.2M–0.3M	Sulfated acid mucopolysaccharides	Blue
0.5M–0.6M	Strongly sulfated acid mucopolysaccharides	Blue
0.7M–0.8M	Heparin, heparan sulfate, keratan sulfate	Blue
0.9M	Keratan sulfate	Blue
All	Nuclei	Red, if counterstained

The amounts given for magnesium chloride are based on a formula weight of 203.3 for the hexahydrate. If the salt used is other than this, adjust the amounts added to each solution to obtain the correct molarity.
Magnesium chloride is hygroscopic. Store appropriately.
The electrolyte molarities for each mucopolysaccharide are not considered absolutes, and personal standardizing and evaluation are required.
This method is usually explained on the basis of magnesium ions competing with alcian blue for binding sites on mucopolysaccharides. As the concentration of magnesium ions increases, so more binding sites are blocked from access to alcian blue.

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.

Bancroft, J.D. and Stevens A. (1982)
Theory and practice of histological techniques Ed. 2
Churchill Livingstone, Edinburgh & London, UK.