A metal-ion buffer provides a controlled source of free metal ions in a manner similar to the regulation of hydrogen ion concentration by a
pH buffer
Buffer may refer to:
Science
* Buffer gas, an inert or nonflammable gas
* Buffer solution, a solution used to prevent changes in pH
* Lysis buffer, in cell biology
* Metal ion buffer
* Mineral redox buffer, in geology
Technology and engineeri ...
A metal-ion buffer solution contains the free (hydrated) metal ion along with a
complex compound formed by the association of the ion with a
ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
in excess. The concentration of free metal ion depends on the total concentration of each component (ligand and metal ion) as well as on the
stability constant of the complex. If the ligand can undergo
protonation
In chemistry, protonation (or hydronation) is the adding of a proton (or hydron, or hydrogen cation), usually denoted by H+, to an atom, molecule, or ion, forming a conjugate acid. (The complementary process, when a proton is removed from a Brø ...
, the concentration of the free metal ion depends also on solution pH.
A considerable improvement in the detection limit of a liquid-membrane
ion-selective electrode An ion-selective electrode (ISE), also known as a specific ion electrode (SIE), is a simple membrane-based potentiometric device which measures the activity of ions in solution. It is a transducer (or sensor) that converts the change in the concent ...
has been achieved by using a metal-ion buffer as internal solution.
[Pretsch, E. (2007]
The new wave of ion-selective electrodes
''Trac-Trends Anal. Chem.'' 26, 46-51
References
Inorganic chemistry
Acid–base chemistry
Equilibrium chemistry
Buffer solutions
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