Bio-Rad DCode™ Universal Mutation Detection System - Manual (Page 62)

6.6 Cooling the Running Buffer and Chiller Settings
1. To chill the buffer in the DCode system, an external chiller is required. For buffer
temperature runs between 5–20°C, the chiller must be able to be set to –20°C and have
a built-in pump to recirculate the coolant (recommended chillers: Haake Model K20 and
Lauda Model RMS-6 or equivalent).
2. Add enough 50% ethylene glycol to the external chiller to fill the coolant reservoir.
Note: To achieve maximum chilling in the electrophoresis cooling tank, do not use ethylene
glycol concentrations greater than 50%.
3. Fill the DCode electrophoresis cooling tank with 7 L of desired running buffer.
Note: It is recommended that the running buffer not be re-used. Because this may affect
the migration rate and band resolution.
4. Connect two pieces of Tygon tubing to the inlet and outlet on the external chiller. Attach
the quick-release connectors to the other end of the tubing.
5. Connect the quick-release tubing connections to the cooling finger leads on the back of the
tank. Turn the chiller on and set the temperature to –20°C. Setting the chiller to –20°C
assures maximum chilling effect, but some chillers may not reach the set temperature due
to the 50% ethylene glycol concentration. Place the temperature control module onto the
electrophoresis tank. The clear loading lid should be on the temperature control module.
Note: For electrophoresis runs between 20–25°C, the chiller should be set to –5 to 0°C.
6. Attach the power cord. Turn the power, pump, and heater on. Set to the desired running
temperature, with a temperature ramp rate to 200°C/hr. This allows the buffer to reach the
desired temperature the quickest.
7. Pre-chill the buffer to the set temperature. It can take 1–1.5 hours for the system to chill
the buffer to 5–10°C. Pre-chilling the buffer overnight at 4°C helps reduce the pre-chilling
time.
6.7 Assembling the SSCP Gel Sandwich
For SSCP gel formats, a 20 x 20 cm gel sandwich size is recommended. To insure proper
alignment, make sure all plates and spacers are clean and dry before assembly. Use caution
when assembling the glass plate sandwiches. Wear gloves and eye protection at all times.
1. Assemble the gel sandwich on a clean surface. Lay the large rectangular plate down first,
then place the left and right spacers of equal thickness along the short edges of the larger
rectangular plate.
2. Place a short glass plate on top of the spacers so that it is flush with the bottom edge of
the long plate.
3. Loosen the single screw of each sandwich clamp by turning it counterclockwise. Place
each clamp by the appropriate side of the gel sandwich with the locating arrows facing up
and toward the glass plates (Figure 6.3).
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