High-performance thin-layer chromatography (HPTLC)
The commercial and enzymatic keratin hydrolysates were
placed on high-performance thin-layer chromatography
plates (Merck silica gel 60 HPTLC). The development
was carried out in butanol/acetic acid/distilled water
(4:1:1 v/v/v) until the solvent front reached the top of the
plate. The HPTLC plate was stained in ninhydrin reagent
(7.5% in butanol/acetone 1:1 v/v). Commercial amino
acids were used as the standard [15].