Bio-Rad Bio-Gel A Agarose Gel - Manual (Page 8)

Section 5
Storage and Sterilization
Packed columns of Bio-Gel A gel may be used
indefinitely if care is taken to prevent microbial growth.
Sodium azide (0.02%) is an effective anti-microbial
agent. For long term storage, maintain pH at neutrality.
Microbial growth is often manifested by the
formation of colonies in the gel bed. A lamp held behind
the column will aid in the detection of colonies. Gel beds
or slurries in which microbial growth has occurred should
be discarded, because complete removal of organisms
from the gel matrix is impossible.
Sterilization procedures must take into account the
physical and chemical properties of the gels, as well as
the resistance of the organisms to be destroyed. With
Bio-Gel A gel, cold sterilization procedures must be
employed because the agarose begins to dissolve above
40 °C. Slurries or packed columns may be cold-sterilized
with a solution of diethyl-carbonate (0.01%). Bio Gel A
gels are not stable in solutions with a pH >7 for extended
periods (greater then 12 hr).
11
dextran is not recommended for V
o
determination because
it is not homogenous in size and may bind nonspecifically
to the gel. Tobacco Mosaic Virus (TMV) or any large
(>150 million) molecular weight marker may be used for
V
o
determination.
Using a standard mixture of proteins allows
verification of the column packing and protein elution as
well as the calibration of the column and the calculation
of the molecular weight of unknown sample proteins. It
also allows comparison of different columns, and
different packing material, without wasting sample.
Bio-Rad’s Gel Filtration Standard is a mixture of five
proteins with known molecular weights: thyroglobulin
(M
r
670,000), bovine gamma globulin (M
r
158,000),
chicken ovalbumin (M
r
44,000), equine myoglobin
(M
r
17,500), and vitamin B12 (M
r
1,350). Myoglobin and
vitamin B12 are visible and can be seen as they migrate
through the column.
10
4006139A.qxd 6/23/98 8:11 AM Page 10