IC with suppressed conductivity is often the method of choice
Organic acids are organic compounds that possess acidic properties. They do not fully dissolve in water, which makes them weak acids. Various industries use organic acids for corrosion treatment and prevention because they are minimally reactive to mineral acids. Juice and wine industries use organic acids to enhance flavor, color, and aroma, as well as for stability and microbiological control.
Organic acid analysis
Many organic acids lack sufficient sensitivity for detection. In addition, other components commonly present in these types of samples have a high UV absorption, which can interfere with the detection of target analytes. Most carboxylic acids ionize sufficiently, making ion chromatography with suppressed conductivity detection the technique of choice to separate a large variety of organic acids with inorganic anions and detect them with high sensitivity while minimizing the sugar interferences.
Partial list of organic acids
- Acetic acid
- Benzoic acid
- Butyric acid
- Caproic acid
- Carbonic acid
- Citric acid
- Formic acid
- Lactic acid
- Malic acid
- Oxalic acid
- Propionic acid
- Tartaric acid
- Valeric acid
Some organic acids are more highly regulated than others. See below for examples from various regulatory bodies.
- WHO: Suggests a provisional tolerable intake of benzoic acid of 5mg/kg body weight per day.
- Health Canada: Established a maximum level of benzoic acid of 1,000 ppm in fruit juice, jams, and packaged fish and meat products.
- FDA: Established a maximum level of acetic acid of 0.25% for baked goods, 0.8% for cheeses, 9.0% for condiments and relishes, 0.5% for fats and oils, 3.0% for gravies and sauces, 0.6% for meat products, and 0.15% or less for all other food categories.
Example application notes
|Application Notes||Sample||MDL||IC Column|
|Determination of Organic Acids in Fruit Juices and Wines by High-Pressure IC (AN 1068)||Fruit juice, wine||0.036–0.069mg/L||Dionex IonPac AS-11-HC Columns|
|Determination of Tartaric Acid in Tolterodine Tartrate Drug Products by IC with Suppressed Conductivity Detection (AN 1002)||Tolterodine tartrate||n/a||Dionex IonPac AS20 Columns|
|Determination of Organic Acids in Wastewater Using Ion-Exclusion Chromatography and On-Line Carbonate Removal (AN 291)||Wastewater||n/a||Dionex IonPac ICE-AS1 Columns|
|Determination of Oxalate and Other Anions in Bayer Liquor Using Ion Chromatography (AN 206)||Bayer liquor||n/a||Dionex IonPac AS17 Columns|
|Citric acid determination in mixed beer beverages||Citric acid||n/a||n/a|