It would be useful to know which equipment you are using (BioRad DR-II, DR-III or Mapper, or any other manufacturer).

The specific equipment is BioRad CHEF Mapper XA. Is there a specific protocol designed for this 185 kbp mixture?

Thank you!

The Mapper XA has an auto-algorithm function. With this, you key in the lowest limit for the molecular weight of interest and the highest limit (in kbp) and the algorithm works out a suitable programme for you.

According to page 8 of the manual, which is available online if you don't have a copy:

3.1 Auto Algorithm

This example outlines the steps for separating a DNA sample with a size range of

220 kb–2,200 kb (the size range of S. cerevisiae).

1. Press AUTO ALGORITHM.

2. After Molecular Weight: Low, key in 220, press K-BASES, then ENTER.

3. After Molecular Weight: High, key in 2200, press K-BASES, then ENTER.

4. The lower line will display Calibration Factor [ ], enter for NC (= no change). This

factor alters the run time by the factor entered between 0.1 and 9.9. Press ENTER for default of 1.0. The lower line displays the physical parameters for the run: 0.5x TBE, 14 °C, 1% PFC agarose. Press ENTER.

5. The screen display shows the calculated electrical parameters: 6 V/cm, Run time= 28:59 (hr), Included angle 120°. Press ENTER or the down cursor key three times to reach the end of the screen.

6. The electrical parameters continue on the next screen: Int. Sw. Tm = 26.31s, Fin. Sw. Tm = 3m48.48s, Ramping factor: a = [ Linear]. The first two entries are the calculated initial and final switch times. Since the times are different, the CHEF Mapper system has selected a switch-time ramp. Press ENTER or the down cursor key to move the prompt past the variables.

7. The final display is A program is in memory. Start the run by pressing START RUN.

I hope this helps.

Hii.......

You can prefer the sambrook , U will get all details what you want.

Another option is u can use the company instrument manual also.

Thank you