6
–
Column Care
Thermo Scientific
Product Manual for IonPac AS31 Columns
Page 42 of 45
155007-01
For Research Use Only. Not for use in diagnostic procedures.
6.5.1
Choosing the Appropriate Cleanup Solution
Table 7
Cleaning Solutions for Anion Exchange Columns
Contamination
Anion Solutions
Hydrophilic
Contamination of
Low Valence
Concentrated hydroxide solutions such as a 10X concentrate of the most concentrated eluent
used in the application is sufficient to remove hydrophilic contamination of low valence.
Hydrophilic
Contamination of
High Valence
Concentrated acid solutions such as 1 to 3 M HCl will remove high valence hydrophilic ions
by ion suppression and elution by the chloride ion.
Metal
Contamination
Metal contamination often results in asymmetric peak shapes and/or variable analyte
recoveries. For example, iron or aluminum contamination often results in tailing of sulfate
and phosphate. Aluminum contamination can also result in low phosphate recoveries.
Concentrated acid solutions such as 1 to 3 M HCl remove a variety of metals. If after acid
treatment, the chromatography still suggests metal contamination, treatment with chelating
acids such as 0.2 M oxalic acid is recommended.
Ionic and
Hydrophobic
Contamination
Concentrated acid solutions such as 1 to 3 M HCl can be used with compatible organic
solvents to remove contamination that is ionic and hydrophobic. The acid suppresses
ionization and ion exchange interactions of the contamination with the resin.
A frequently used cleanup solution is 200 mM HCl in 80% acetonitrile. This solution must
be made immediately before use because the acetonitrile will decompose in the acid solution
during long term storage.
Nonionic and
Hydrophobic
Contamination
Although this is extremely rare, nonionic and hydrophobic contaminants can contaminate an
ion exchange column. The symptoms include reduced chromatographic efficiency, elevated
pressure or tailing for a subset of analyte ions. Retention is unaffected by this type of
contamination. Organic solvents can be used alone if the contamination is nonionic and
hydrophobic. The degree of nonpolar character of the solvent should be increased as the
degree of hydrophobicity of the contamination within the range of acceptable solvents.
