The solvents generally used for plant
dye extraction are ethanol, methanol,
acetone, chloroform, ether, clove oil, etc.
The dried material powder is weighed and
soaked in solvent in different percentages
and time durations. The crude dye extract
can be used for tissue staining after
extraction or can be further applied for
solvent evaporation in order to concentrate
the dye solution before staining.
Alternatively, the dried plant powder is
soaked in solvent to allow effective
percolation, then the soaked powder is
extracted in the solvent using Soxhlet
Extractor (Steam Heated Extractor). The
extract is then concentrated using rotary
evaporator and may further drying in the
drying oven (Okolie. 2008). Finally, the
extract is obtained in powdered form which
will be dissolved in the solvent or buffer at
the desire concentrations before tissue
staining.
Supercritical fluid extraction (SFE), an
alternative to conventional solvent
extraction for separation of organic
compound in many analytical processes as
well as extraction of plant natural dye has
gained wide acceptance in recent years
since this technique is safe for health,
inexpensive and harmonize with nature. SFE
uses carbon dioxide as a solvent. This
method is based on the enhanced solvating
power of gases above their critical point
(Samanta and Konar, 2011). Cardoni et al.
(2000) studied the extraction of lycopene
and β-carotene from ripe tomatoes using
SFE. The detail information and procedure
of this method has been reported by
Sapkale et al. (2010).