4. Lengthy transfer times are not recommended. Do not leave this instrument unattended.
Joule heat can be generated rapidly during semi-dry blotting. Transferring longer than
2 hours can damage the unit.
5. Power supply requirements. The Trans-Blot SD cell should only be used with the
microprocessor-controlled Model 200/2.0 power supply (catalog numbers 165-4761 and
165-4762), or the Model 1000/500 power supply (catalog numbers 165-4710 and
165-4711). Do not use the Model 250/2.5 power supply with this apparatus. The low
voltage, high current operating conditions of the Trans-Blot SD cell are not compatible
with the Model 250/2.5 power supply, and will cause the power supply to blow a fuse.
6. Do not operate this instrument in ambient temperatures exceeding 50 °C.
Important
This Bio-Rad instrument is designed and certified to meet IEC 1010-1* safety standards.
Certified products are safe to use when operated in accordance with the instructtion
manual. This instrument should not be modified in any way. Alteration of this instrument
will:
• Void the manufacturer's warranty
• Void the IEC1010-1 safety certification
• Create a potential safety hazard
Bio-Rad is not responsible for any injury or damage caused by the use of this instrument
for purposes other than for which it is intended or by modifications of the instrument not
performed by Bio-Rad or an authorized agent.
*IEC 1010-1 is an internationally accepted electical safety standard for laboratory instruments.
Section 4
Trans-Blot SD Assembly
To determine the optimum conditions for a particular sample, a time course of transfer
should be performed. Since many factors affect transfer e.g. molecular weight, pI, and
porosity of the gel, transferring for the full suggested time may not be necessary.
4.1 Preparation for Blotting
1. Prepare the transfer buffer. See Section 5 for buffer formulation.
Note: Buffer preparation is extremely important. Do not adjust transfer buffer pH by
addition of acid or base unless specifically indicated in the instructions. Improperly
prepared buffer will cause excess heat generation and safety hazards. Use only high
quality, reagent grade methanol. Contaminated methanol can result in increased transfer
buffer conductivity, as well as poor transfer of macromolecules.
2. Following electrophoresis, equilibrate the gels in transfer buffer. Equilibration facilitates
the removal of electrophoresis buffer salts and detergents. If the salts are not removed, they
will increase the conductivity of the transfer buffer and the amount of heat generated
during the transfer. Also, low percentage gels (<12% acrylamide) will shrink in methanol-
containing buffers. Equilibration allows the gel to adjust to its final size prior to
electrophoretic transfer. The length of time required for equilibration is dependent on the
gel thickness. For example, 15 minutes for a 0.75 mm SDS-PAGE gel.
6
