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The use of ion chromatography in food and beverage analyses

Analytical techniques
Foods, beverages and their raw materials, may be chemically tested for a wide variety of constituents. The presence of contaminants such as pesticides, antibiotics, heavy metals and adulterants etc. should also be determined. A wide variety of analytical techniques and instruments may be used for testing at all stages of the food and beverage production process.
These techniques include pH measurements, ion selective electrodes, polarography, differential scanning calorimetry, mass spectrometry and its hyphenated variants, inductively coupled plasma spectroscopy, high performance liquid chromatography (HPLC), ultra high performance liquid chromatography, gas chromatography, ion chromatography (IC) and UV/Visible spectrophotometry, Raman spectroscopy and Fourier transform infra-red spectroscopy etc. All of these techniques each have their merits and application suitabilities.

The merits of IC
This discussion highlights the relevance of IC within food and beverage laboratories. IC is a derivative of HPLC. Here, the use of anion/cation exchange/pair/exclusion chromatography and/or detection of charged species is involved.
IC detection advantages are accuracy, speed, reproducibility, specificity and sensitivity. An IC conductivity detector must provide for low noise, high sensitivities, low drift, a wide range and fast response times.
Another benefit of IC is that it will enable the whole of a group of analytes of interest, to be determined within the same chromatographic run, with little or no sample pre-treatment.
IC is increasingly used for many measurements, such as:

  • Lactic, acetic, citric, malic, phosphoric and other acids in coffees.
  • Citric, ascorbic and acetic acids in other foods and beverages.
  • Heavy metal limits in dairy products.
  • Sucrose, lactose, galactose, and glucose in lactose-free dairy products.
  • Propylene glycol, chloride, sulphites and nitrate, in beers and wines.
  • Fluoride in teas.
  • Sulphates, phosphates, nitrates and chlorides in sugars and sweeteners.
  • Sulphates, phosphates and chlorides in sodium carbonate raw materials.
  • Glucose, fructose, and sucrose traces in alcoholic spirits.
  • Amino acids in specialised nutritional feeds.
  • Fumaric, citric, and propionic acids in animal feeds.
  • Calcium, magnesium, sodium, ammonium and potassium in sugar solutions.
  • Carbonate in sparkling drinking waters.
  • Iron, sodium, ammonium, potassium, calcium, magnesium, strontium, barium chloride, nitrite, bromide, fluoride, nitrate, phosphate and sulphate in mineral waters.
  • Arsenic in rice.
  • Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) contamination in feed waters.
  • Phosphoric acid in cola beverages.

If a laboratory has an existing HPLC system, then that system may be successfully expanded to an IC system by the use of an additional stand-alone conductivity detector.
Flexibility is enhanced by the absolute choice of mobile phase.
If there is no existing HPLC system, then a modular IC system may be used. Some modules, such as UV/Visible, electrochemical, refractive index and fluorescence detectors, autosamplers, pumps and post column reactors, may be added at a later stage, to further expand the IC system’s capabilities and/or to convert the system to an HPLC system.
Modularity ensures that one single system will accommodate a scientist’s current and future requirements.

For further information, please contact:
Ade Kujore, Marketing, Cecil Instruments Ltd, Milton Technical Centre, Cambridge CB24 6AZ, UK.
Tel: +44 (0)1223 420821
Email: ade.kujore@cecilinstruments.com or
info@cecilinstruments.com
Web: www.cecilinstruments.com

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