Table 2.

Advantages and disadvantages of purification methods of polysaccharides.

Sr. no	Methods	Advantages	Disadvantages
1	Graded precipitation	Easy-to-operate; often used firstly.	Unable to obtain homogeneous polysaccharide fractions.
2	Salting-out method	Cost-effective.	Low efficiency; easy to form co-precipitation.
3	Metal coordination	Good specificity.	It is not easy to find a proper coordination reagent.
4	Quaternary ammonium salt precipitation	Often used to purify acidic polysaccharides and neutral high-MW polysaccharides; good selectivity.	Need to accurately adjust/control ionic strength and pH of the solution.
5	Column chromatography:
	i. Cellulose column	Purity of the eluate is high.	Low flow rate; long time-consuming.
	ii. Anion exchange column	Most widely used; fit for purifying various acidic/neutral polysaccharides and mucopolysaccharides.	Sometimes the height of column bed may change when pH of buffer changes.
	iii. Gel column	Principle of molecular sieve; often used to further purify polysaccharides.	The ionic strength of eluent should not be less than 0.2 mol/L.
	iv. Affinity column	High efficiency; easy-to-operate.	Difficult to find a proper ligand for a given polysaccharide.
6	Ultracentrifugation	Good efficiency.	High requirement for equipment; mostly used for semi-micro preparation of polysaccharide.
7	Ultrafiltration	Principle of molecular sieve.	Low yield; long time-consuming.
8	Preparative zone electrophoresis	Good separation effect.	Long time-consuming; small purification capacity; only used for semi-micro preparation.