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Related Concept Videos

Buffer Systems in the Body01:19

Buffer Systems in the Body

4.2K
Chemical buffers play a critical role in the body's regulation of pH levels. These systems contain one or more compounds that stabilize pH changes by neutralizing strong acids or bases. When pH levels drop, hydrogen ions bind to a weak base; when pH levels rise, hydrogen ions are released. This dynamic process helps maintain pH within a narrow and stable range essential for normal physiological function.
A typical buffer system in bodily fluids includes a weak acid and its corresponding...
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Extraction: Effects of pH00:53

Extraction: Effects of pH

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Consider a neutral form of an amine, B, with a partition coefficient, K, in a liquid mixture containing organic and aqueous phases. The pH of the aqueous phase affects the charge on acidic and basic solutes, and the charged form is usually more soluble in the aqueous phase. Suppose the conjugate acid form of the amine is soluble only in the aqueous phase while the base form is soluble in both phases. Then the distribution coefficient, D, can be given as the ratio of amine concentration in the...
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Capillary Electrophoresis: Applications01:30

Capillary Electrophoresis: Applications

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Capillary electrophoretic separations offer various modes, each with unique applications. These modes include capillary zone electrophoresis, capillary gel electrophoresis, capillary array electrophoresis, capillary isoelectric focusing, capillary isotachophoresis, micellar electrokinetic chromatography, and capillary electrochromatography.
Capillary zone electrophoresis (CZE) separates ionic components based on their electrophoretic mobility. It has been used to separate proteins, amino acids,...
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Protein Buffers in Blood Plasma and Cells01:20

Protein Buffers in Blood Plasma and Cells

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The human body utilizes protein buffer systems to maintain a stable pH. These systems capitalize on the dual role of amino acids, which can act as acids or bases by accepting or releasing hydrogen ions in response to pH changes. Protein buffer systems are particularly significant in the extracellular fluid (ECF) and intracellular fluid (ICF) of active cells, where structural and functional proteins provide substantial buffering capacity.
Certain amino acids can exist in a zwitterion state at a...
4.1K
Buffers02:56

Buffers

173.9K
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...
173.9K
Extraction: Advanced Methods00:56

Extraction: Advanced Methods

1.2K
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is...
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Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters
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Comprehensive study of buffer systems and local pH effects in electromembrane extraction.

Magnus Saed Restan1, Henrik Jensen2, Xiantao Shen3

  • 1School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway.

Analytica Chimica Acta
|August 28, 2017
PubMed
Summary

Electromembrane extraction (EME) using different buffers showed that lower pH acceptor phases (≤4.8) yielded higher drug recoveries (66-97%). Elevated pH conditions at the membrane interface negatively impacted EME performance.

Keywords:
Boundary layerBuffersElectrolysisElectromembrane extraction (EME)Sample preparation

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Area of Science:

  • Analytical Chemistry
  • Separation Science

Background:

  • Electromembrane extraction (EME) is a sample preparation technique.
  • Optimizing buffer systems is crucial for efficient EME of basic drugs.

Purpose of the Study:

  • To investigate the effect of different buffer types and pH on electromembrane extraction of basic drugs.
  • To understand and address pH stability issues in the acceptor/supported liquid membrane interface during EME.

Main Methods:

  • Tested phosphate, acetate, and formate buffers (pH 2.0-6.8) in a 96-well EME system.
  • Analyzed five basic drugs (haloperidol, loperamide, methadone, nortriptyline, pethidine) using HPLC-UV.
  • Investigated extraction recovery, current, and pH stability with varying buffer strengths and voltages.

Main Results:

  • Effective pH stabilization was achieved with buffers in both donor and acceptor phases.
  • Higher extraction recoveries (66-97%) were obtained with acceptor phase pH ≤ 4.8.
  • Lower recoveries (21-62%) were observed at acceptor phase pH 5.8-6.8 due to elevated pH at the acceptor/SLM interface.

Conclusions:

  • The pH at the acceptor/supported liquid membrane interface significantly influences EME efficiency for basic drugs.
  • Elevated pH conditions at the interface, independent of buffer strength or voltage, reduce extraction recovery.
  • Understanding and mitigating these pH effects is critical for advancing EME technology.