Ion Chromatography

Ion Chromatography

Ion Chromatography (IC) measures ionic analytes based on their relative affinity for a mobile and stationary phases.  This technique is commonly employed to measure anions and cations in a variety of sample matrices.

Methods

Galbraith Laboratories has two IC methods.  Each is written to handle a wide range of sample types.  The first method applies to the analysis of anions; the second method applies to analysis of cations.  Click below to view a copies of the method summaries:

ME-4A-Anions-by-Suppressed-Ion-Chromatography-Chloride

ME-4D-Method-Summary-for-Cations_NH4_-by-Supressed-Ion-Chromatography

Detectors

A Conductivity Detector measures the change in the conductivity of the mobile phase during elution of an analyte.

A Pulsed Amperometric Detector (PAD) measures the change in the amperometric potential of the mobile phase during elution of an analyte.

Preparation

Each successful analysis begins by adequately dissolving the sample for analysis.  Typically, the mobile phase of the method is used as the dissolution solvent.  In cases where the test substance is not soluble in the mobile phase, the results may be reported as “extractable.”

For some analytes, expecially halogens and halides, the sample can be combusted in a Parr Bomb prior to analysis.  Click here to view more information on this preparation technique.

Analysis

IC instruments are externally calibrated with the use of calibration standards.  Sample solutions are injected onto the column and are separated based on their relative affinity for the stationary (column) and mobile phases.  Components of the analysis solution are detected using one of the available detectors to provide a sample chromatogram.  The area under the desired (target) peak(s) is integrated and is compared to the calibration curve to provide the concentration.

Quantitation Limit

Unless otherwise evaluated, the quantitation limit (QL) depends on the concentration of the lowest calibration standard used to calibrate the instrument.  This concentration is typically 0.2 mg/L (in solution).  The samples solution concentration is expressed on the wt/wt basis using the sample mass taken for the analysis.  Results that read below the QL are reported as less than values, i.e <50 ppm.

Results

Results are reported using the mass of sample originally taken for the analysis.  Typical reporting units are ppm, mg/L, or %.  Other units may be reported.  

For any questions on IC analysis, please Contact a member of our Technical Team for more information.

Regulated Submissions

The general methodology is suitable for the analysis of regulated samples.  The method is considered validated to a reference substance, but not to the sample matrix unless a formal validation is conducted.  Click here to see more information on Method Validation.