Buffer Additives for Capillary Electrophoresis.

Additive  Function  Organic Solvents Modify EOF Urea Solubilize Proteins Denature oligonucleotides Surfactants   MECC, Separation of neutral Species Charge reversal of Capillary Wall Cellulose Derivatives Reduce EOF Sieving Mechanism Cyclodextrins Separation of Positional Isomers or enantiomers

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Buffer Hints in Capillary Electrophoresis.

Making Your Own Buffers As a general rule in making your own buffers, they are most effective within one to two pH units of its pKa. It is best to begin developing your HPCE method with a low concentration buffer. This will avoid non-specific ionic strength effects and will reduce Joule heating. A 50mM concentration […]

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Capillary Conditioning in Capillary Electrophoresis

New capillaries should be conditioned before you use them. 1.Filter all solutions to be used on your capillary through a .45µ or 0.2µ syringe filter. 2.Treat the capillaries by running 0.1N NaOH solution through them on your CE unit. 3.Rinse the capillaries with CEwater or HPCE grade water for 5 minutes. 4.Final step is to […]

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CE Capillary Storage in Capillary Electrophoresis

When storing a Capillary after use, follow these simple instructions to increase the capillary life. 1.Filter all solutions to be used on your capillary with .45µ or .2µ filter. 2.Rinse the capillary with .1M NaOH solution for 5 minutes. 3.Rinse the capillary with CEwater or CE grade water for 5 minutes. 4.If possible, blow nitrogen […]

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Changing Capillary Dimensions in Capillary Electrophoresis

When you change the ID of your capillary in your CZE system, the following changes can be expected. It is important to be aware of these effects. Joule Heating: An increase ID or length of your capillary will increase the amount of heat due to Joule Heating. Smaller ID and length of capillaries are utilized […]

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Changing Conductivity in Capillary Electrophoresis.

When you change the Conductivity of your CZE method, the following changes can be expected. Joule Heating: Reducing or lowering the conductivity will reduce the amount of Joule Heating in your capillary. Current: A lower conductivity results in a lower Current. Resolution: When conductivity is reduced sample loading can be adversely effected. Migration Time: A […]

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Choosing a Proper Buffer in Capillary Electrophoresis of Proteins

The diverse types and characteristics of proteins makes selecting a proper buffer very challenging. Factors to consider when choosing a buffer for proteins are: A. The protein’s pI and pK’s B. The solubility of the protein C. The amount of glycosylation D. The effect pH has on the folding or unfolding of the protein

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Correction for late migrating peaks in Capillary Electrophoresis.

The normalization of electropherograms is required as slower moving peaks generate a wider peak width than the faster moving peaks. The area of any peak is a function of both its peak width and height. This must be performed on most CE runs because the first migrating peak will be understated in area and late […]

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Effects of Changing EOF in Capillary Electrophoresis.

When you change the Electro Osmotic Flow (EOF) of your CZE method, the following changes can be expected. Joule Heating: Reducing or lowering the EOF will reduce the amount of Joule Heating in your capillary. Migration Time: Changes in EOF will directly effect the migration times of all of your analytes. The changes are not […]

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Hint on Serum Proteins and Capillary Electrophoresis.

When performing Serum Protein or iso LDH-isoAmylase-iso CK or iso phosphatase analyses, it may happen that a protein (immunoglobulin or enzyme) binds to another protein (such as an immuno complex) or is present under a dimer, tetramer form. It is suggested that you displace these molecules before placing them into solution for HPCE analysis. One […]

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How do I use the CE Window Maker for a different size detection windows?

The MicroSolvCE Window Maker™ comes supplied with a heating module suitable for burning a detection window that is approximately 2mm wide. Replacement Modules for 1, 4, or 7mm can be obtained separately as accessories. The default module can be removed and the alternate can be easily plugged into its place on the Window Maker unit. The […]

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How to Condition Controlled & Zero EOF Capillaries.

Capillary Conditioning Procedure: Never Use Strong Bases on these Capillaries Carefully remove the capillary from the shipping/storage container. Remove protective polyimide coating by using 98% fuming sulfuric acid heated to 100ºC. One drop should be sufficient for complete removal. The MicroSolv Window Maker be used as well as long as you do not allow the […]

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How To Perform an Ohms Law Plot.

Ohm’s Law Plot to Optimize your Separation can bring many benefits and is essential for good CE Methods. Select the optimal Voltage Setting for your Separation. Maximize the Efficiency of your Method. Learn the Upper Voltage Limits of your Method. Use to Validate your Capillaries and Columns in your Method. Performing an Ohm’s Law Plot […]

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How To Properly Cut a Fused Silica Capillary for CE.

A Recommended Cleaving or Cutting Procedure for Simplus Brand or any Bare Fused Silica Capillaries is as follows: Cleaving Procedure: Place the Capillary over a large Diameter Radius Surface such as large pipe or tube. Keep the Capillary under slight Tension. Hold a fresh, Clean Cleaving Stone at an approximately 30º angle to the Capillary. […]

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Ionic Strength Changes in Capillary Electrophoresis

When you change the Ionic Strength (Buffer Concentration) in your CZE method, the following changes can be expected. Joule Heating: An increase in ionic strength (buffer concentration) will produce more heating. See the effects of change in temperature for effects. Viscosity: An increase in ionic strength or buffer concentration will cause an increase in viscosity. […]

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Migration Time Shifting in Capillary Electrophoresis.

If migration time shifting is the only problem you are observing from your electropherogram, it is recommended that you check the accuracy of your power supply. If you find that the power is clean and constant then you should check your capillary. Sometimes the inner surface of the capillary becomes modified by the buffers, solutes […]

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pKa Values of Common Capillary Electrophoresis Buffers

The dissociation constant (pK) is the pH at which 50% of a compound is protonated. Some compounds will have more than one pK. This can be the same or differ from the compound’s pI or isoelectric point. Buffer pK Acetate 4.75 Boric (pK1) 9.14 Boric (pK2) 12.74 Boric (pK3) 13.80 CAPS 10.40 Citrate (pK2) 4.76 […]

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Temperature Effects and Joule Heating in Capillary Electrophoresis.

When the temperature of your CZE method changes, the following can be expected. Changing anyone of these parameters in CZE can reduce your coefficient of variation therefore it is important to control your temperature accurately. pH: High temperatures resulting from Joule heating can shift the pH. Viscosity: Higher temperatures can decrease your viscosity. Conductivity: With […]

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Troubleshooting Common Injection Problems in Capillary Electrophoresis

Some of the most common problems with HPCE is caused by problems or errors created during the injection procedure. Following is a short table of Problems and Causes and Solutions to these problems. Problem Cause/Solution  No Injection at all 1.Replace the capillary or unplug the capillary 2.Check the pressure or vacuum of the system 3.Check […]

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Using a Water Plug in Capillary Electrophoresis.

It is generally suggested that all CE injections include a water plug. The purpose of the plug is to increase your precision. The rationale for this is that it does not allow your analytes to diffuse back into “buffer” vial during the injection process; the capillary may become pressure free when changing the vials. During […]

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Using a Water Rinse When Separating Proteins by CE.

It is recommended that when your samples are high concentrations of protein or simply a very “sticky” protein, that immediately before you inject the sample, between runs, that you dip your capillary in CEwater. It is further recommended that immediately after the separation, that you dip your capillary in CEwater. This will assist in removing […]

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Using Buffer Additives in CZE

When you add Modifiers (Buffer Additives) to your CZE method, the following changes can be expected: Joule Heating: Adding high concentrations of organic modifiers or other additives can cause an increase in current or an increase in Joule Heating. Viscosity: Adding high concentrations of additives such as methylcellulose will increase viscosity. Also this can cause […]

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Voltage Effects in Capillary Electrophoresis.

When the voltage of your CZE method changes, the following can be expected. Changing anyone of these parameters in CZE can reduce your coefficient of variation. Temperature (Joule Heating): When voltage increases in CZE, a higher field strength results. This can cause temperature gradients in your capillary. Band broadening may result. Electro Osmotic Flow EOF: […]

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