Keating:Experimental Protocols:Capillary Electrophoresis
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Instructions for using Beckman PACE MDQ capillary electrophoresis
- written by Nora 4/21/05
- Prepare buffers and samples
- choose a buffer or set of buffers to use as the running and sample buffers, ideally ~2 pH units above pI of protein (if known)
- when in doubt, start with borate buffer pH 8.0
- concentration 20-200mM (start with 50mM)
- salt in buffer will interfere with conductivity and separation
- need 3 vials of each buffer (~1.5ml each) – top with orange caps
- don't fill past the shoulder of the vial
- samples should be approximately 50uM in a minimum volume of 50ul of sample buffer (same as running buffer)
- not much of the sample will be injected and the majority of the sample can be recovered at the end of the experiment
- place samples in PCR tubes in plastic vials with springs, topped with gray caps
- also prepare water, 0.1M HCl, 0.1M NaOH, methanol, and waste vials
- filter all samples and buffers with 0.22um filters
- make fresh buffer aliquots for every ~10-20 runs / 2-3 weeks
- Open PACE MDQ software program - 32Karat
- software is very similar to the HPLC software
- instrument should already be on
- Turn on UV lamp to warm up for at least 15 min
- Make a directory for yourself in D:\Users\CE
- Sign in the log book
- Change cartridge and/or capillary if desired.
- in software, manual control – press load to move vial trays forward
- open tray and cartridge cover
- unscrew the insertion bar keeping the cartridge in place and remove the cartridge
- follow instructions in the installation and maintenance manual to change the capillary
- reverse instructions to replace
- Place sample and buffer vials in buffer and sample trays
- pay attention to where the tray positions for writing the methods
- below is the standard positions for the minimum buffers needed
- samples placed in the back sample trays can be kept at particular temperature, but can also be placed in buffer trays (only RT)
- Methods
- use examples in D:\Users\CE\General Methods\
- if it's the first time using the capillary ever or in several months, start with condition.met capillary to go through extensive rinsing
- otherwise use wash.met to do a quick rinse
- for separation methods, use bufferXaYb.met where Xa is position of rinse buffer vial and Yb is position of separation buffer vial
- separation methods include a few washes, injection of the sample, and separatation of the sample under voltage
- method files assume injection of buffer as the sample (baseline)
- after all runs have been performed, use shutdown.met to give the capillary a final rinse, includes turning off the lamp
- any of methods can be modified, including absorbance wavelenth, sample/buffer positions, length of time for separation or washes, etc, but please save in your directory's methods folder
- to run a single method, press the blue arrow
- save the data file in your directory's data folder
- Sequences
- to run multiple samples, use a sequence file to specify the method, data file, and sample position of each sample
- for examples, look in D:\Users\CE\Nora\Sequences
- you need to name the data files by typing in the sample, including the entire path with your directory
- press the green arrow to start the sequence
- sequence can be modified in the later steps and saved while running
- Notes
- if window pops that coolant is low, refill coolant
- open bottom panel
- connect tube attached to syringe
- pour in coolant in 5ml increments, just let flow in
- until level of coolant in viewing tube is between the black lines
- if window pops that coolant is low, refill coolant