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More Information
Educational Support
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Agarose Gel Information
Voltage Selection Guide for Agarose Gels*
| Voltage |
Gel Size |
Electrophoresis
Time* |
FOTO/Force®
Power Supply |
10V
10V |
7.1 x 9.3 cm (mini-gel)
12 x 14 cm |
20-24 hours
30 hours |
120, 150
120, 150 |
20V
20V
20V |
7.1 x 9.3 cm (mini-gel)
12 x 14 cm
20 x 25 cm |
12-16 hours
20-24 hours
48 hours |
150, 250, 300
150, 250, 300
150, 250, 300 |
60V
60V
60V |
7.1 x 9.3 cm (mini-gel)
12 x 14 cm
20 x 25 cm |
2 hours
6 hours
24 hours |
150, 250, 300
150, 250, 300
150, 250, 300 |
120V
120V
120V |
7.1 x 9.3 cm (mini-gel)
12 x 14 cm
20 x 25 cm |
50 minutes
2.5 hours
9 hours |
120, 150, 250, 300
120, 150, 250, 300
120, 150, 250, 300 |
| * 1% agarose gels, 5 mm
thick, run in 1X Buffer |
Marker DNA separated on a 1% agarose mini-gel
at 10V (FOTO/Force® 120) for 24 hours.
120 Volts
If electrophoresis results are required quickly, "120V" is the voltage setting to select. Depending on the sizes of fragments to be resolved, a standard FOTODYNE mini-gel (7.1 x 9.3 cm) can be run in as little as 30-40 minutes at 120 Volts with adequate results. At 120 Volts, however, heat generated in the electrophoresis chamber may cause smearing of the bands or uneven banding patterns on the gel.
60 Volts
"60V" is an intermediate setting, which allows gel running times somewhere between those run at 120 Volts and 10 Volts. A mini-gel can be run in approximately 90 minutes at 60 Volts, again depending on the samples involved.
10 Volts
The "10V" setting is used to run gels slowly for long periods of time. At 10 Volts, gels can be loaded and started at the end of one class period, and run overnight until class the next day (23-24 hours). Samples run on a gel at 10 Volts should resolve better than samples of the same distance on a gel run at higher voltages.
Combined Voltages
If one of the output voltage settings does not provide the desired running conditions, combining voltages may be the solution. For example, a gel can be partially run at 10 Volts for a few hours, then run to completion at 60 Volts or 120 Volts.
Recommended Agarose Gel Concentrations
Size of Linear DNA
Framents to be Separated |
Optimum Agarose
Concentration |
200-3000 bp
400-7000 bp
500-10000 bp
800-12000 bp
1000-30000 bp |
1.5%
1.2%
1.0%
0.7%
0.5% |
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NOTE:
For general gel electrophoresis an agarose concentration of
0.8 - 1.0% is recommended. If the separation is not satisfactory,
adjust the agarose concentration to meet your needs. |
Gel Electrophoresis Troubleshooting
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Ideal Gel |
Overloaded Gel |
Punctured Wells |
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0.8% agarose mini-gel in 1X TBE buffer run at 60 Volts for 2 hours. |
Bands smeared in all lanes. Too much DNA loaded. |
During loading, Lane 2 was punctured with the micropipette tip.
In more severe cases, DNA is lost through the hole in the well.
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Bubble in Lane |
Poorly Formed Wells |
Gel Made with Water
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Bump in band in Lane 4. Bubble in Lane 4 of agarose gel. |
Wavy bands in all lanes. Comb removed before gel was completely set. In this case, comb was removed eight minutes
after pouring gel. |
Bands smeared in all lanes.
Water, instead of 1X TBE buffer,
was used to prepare agarose.
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Well contents:
Lane 1: Lambda DNA, no digestion
Lane 2: EcoR I cut Lambda DNA
Lane 3: Hind III cut Lambda DNA
Lane 4: EcoR I & Hind III cut Lambda DNA
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