Buffer Exchange Method
Buffer Exchange Method - Related Videos
10:27
Microfluidic Buffer Exchange for Interference-free Micro/Nanoparticle Cell Engineering
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Cited by 4 •
2016
This protocol describes the use of an inertial microfluidics-based buffer exchange strategy to purify micro/nanoparticle engineered cells with efficient depletion of unbound particles.
02:56
Buffers
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2020
A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a buffer. Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl...
04:35
Buffers - Concepts
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2020
Buffers When an Arrhenius acid (HA) is added to water, it dissociates into its conjugate base (A-) and a hydrogen cation (H+). HA + H2O → H+(aq) + A-(aq) The amount of hydrogen ions present in the solution determines the acidity of the solution, where more hydrogen ions indicate a lower or more acidic pH. Similarly, when a strong Arrhenius base (BOH) is added to water, it dissociates into its conjugate acid (B+) and a hydroxide ion (OH-). BOH + H2O → B+(aq) + OH-(aq) Generally, the addition of...
14:31
Buffers - Student Protocol
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2020
Source: Smaa Koraym at Johns Hopkins University, MD, USA Preparing 50 mM NaH2PO4 Buffer, pH 7Expand In the first part of this experiment, you will prepare a sodium phosphate solution buffered at pH 7.0. Monosodium phosphate is a weak acid with the conjugate base, disodium phosphate. Unadjusted monosodium phosphate solutions usually have a pH of about 4 - 6. Buffers are most effective close to their pKa, which is 6.8 to 7.2 for monosodium phosphate. So, you will use NaOH to push the...
08:13
Buffers - Instructor Prep
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2020
Source: Smaa Koraym at Johns Hopkins University, MD, USA Preparation of SolutionsExpand Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed. To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves. All solutions for this lab should be prepared in a chemical fume hood. Prepare 100 mL of a 1 M NaOH solution. Note:...
FAQs
These formats use different selective separation arrangements. Dialysis membranes and ultrafiltration retain larger biomolecules while permitting smaller ions or unwanted solutes to pass through a membrane. Desalting columns use a separation matrix that allows small solutes to enter while larger molecules remain outside that space. The shared outcome is altered solution composition without removing the macromolecule of interest.
Retention depends primarily on the size relationship between the molecule and the membrane or separation matrix. Larger proteins, nucleic acids, or other macromolecules remain associated with the sample, whereas smaller ions and unwanted solutes can cross the membrane or enter the matrix. This size-selective behavior allows solution components to change while preserving the material needed for later experiments.
Changing pH or ionic strength places biomolecules in chemical conditions compatible with a specific downstream objective. Appropriate buffer composition can support molecular stability and prepare a sample for purification, enzyme assays, structural analysis, or labeling. Because these conditions influence the sample environment, controlling them carefully also helps maintain experimental reproducibility across biological preparations.
Sample concentration must be controlled together with buffer composition because both influence whether biomolecules remain stable and experimentally useful. Careful concentration control helps preserve molecular stability during solution replacement and reduces variation between preparations. This is especially important when exchanged samples proceed to purification, enzyme assays, structural analysis, or labeling, where inconsistent starting conditions can affect interpretation.
Researchers should identify the required final buffer composition, including the desired pH and ionic strength, and select a separation format that retains the macromolecule while removing smaller solutes. They should also plan how to maintain an appropriate sample concentration. These controls align the exchange with the next experimental step and help produce a stable, reproducible biological sample.
Buffer exchange is useful when salts or other unwanted solutes would leave a biological sample in unsuitable conditions for the next procedure. It can place proteins, nucleic acids, or other macromolecules into a buffer compatible with purification, enzyme assays, structural analysis, or downstream labeling. In each case, the exchanged solution supports the requirements of the intended analysis or preparation.
Within biology workflows, this method connects sample preparation to downstream experimentation by adjusting the chemical environment around retained macromolecules. Removing salts and changing pH or ionic strength can make the sample suitable for multiple research uses, while concentration control helps preserve stability. The result is a more consistent starting material for purification and functional, structural, or labeling studies.