2.8. Extraction, fractionation and estimation of free
amino acids
The 70% alcohol – soluble fraction of the freeze-dried
mushroom samples was fractionated on a Dowex –
50H+ column into sugars and amino acids, as described
by Rajarathnam, Wankhede, and Zakia Bano (1987).
The amino acid fractions were pooled, ammonia expelled
under flash evaporation and pH brought down
to 4.3 using 2 N HCl, and the whole concentrated under
low pressure. Twenty microlitres were injected into a
Schimadzu Automat Analyzer. The resolved peaks were
identified and computed with the standards run under
similar conditions