Generally, chromatography is
separated in to two categories. It is depending on the solvents flows down to
the column. If solvent granted to the flow down in the column by gravity, at
that time it is called gravity column chromatography. If the column pressured
down the column by positive air pressure, at that time it is called flash
chromatography. Many type
of chromatography like column
chromatography, affinity column chromatography, aluminium oxide
chromatography, silica chromatography, adsorbents chromatography, molecular
chromatography, preparative chromatography, stationery phase chromatography,
large scale chromatography, etc. in all type of chromatography silica gel
powder is use to separation of mixture in components. This is use in research
and development laboratories, pharmaceutical companies and chemical industries.
In column chromatography,
there are two type of adsorbents silica and aluminium oxide powder is used in
organic chemistry. All these adsorbents having different particle grade-mesh size
as displaying number on container label as silica gel 60, 30-70, 60-120,
60-200, 70-230, 100-200, 200-400, 230-400, 400-800. All particle size affects
how to solvent flows down though the column. Smaller (finer) particle size is
use in flash chromatography and larger (coarser) particle size is use in
gravity chromatography. For example, 70-230 mesh use in gravity columns and
230-400 mesh use in flash columns.
Aluminium oxide is used in
typically in column chromatography because it is quite delicate to the amount
of water which is bound to alumina. In that water level is more which is bound
to it and bind organic compounds. In the analysis of column chromatography, thin
layer chromatography is the
best technic to isolate compounds from the mixture. Usually, the isolated
compounds are colorless. In chromatography the "G" stands for Gypsum
and suggests calcium sulfate hemihydrate, a sophisticated gypsum has been
included in adsorbents ingredients. The "F" indicates the existence
of a short wave UV indicator that is fluorescent at 254 nm. Thin layer
chromatography having Z grades sizes using silica gel powder. The grade size
like silica gel for TLC GF 254 for making glass plates, silica gel G and H for
TLC, in which silica gel G offer with binder and silica gel H offer without
binder process. Silica gel gf254 is a homogeneous, white and fine powder of an
average practical size about 15 µm that is containing around 1.5% fluorescent
indicator and 15% calcium sulphate having maximum intensity at 254 nm.
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