Determination of organic acids in industrial streams by ion chromatography after solid-phase extraction

Organic acids are frequently found in various industrial streams. Historically, ion-exclusion chromatography has been the method of choice for organic acid analyses. However, because of the gel-type packings used and the large column diameter required, ion-exclusion chromatographic methods are usually associated with relatively low column efficiency and moderate detection sensitivity. Furthermore, due to the separation mechanism, gradient elution is not practical in ion-exclusion chromatography. Hence, simultaneous separation of a wide range of organic acids by ion-exclusion chromatography becomes difficult. Ion-exchange chromatography based on high-performance column packings, on the other hand, offers excellent column efficiency, high detection sensitivity and wide separation capacity. In this work, we report a gradient method using an anion-exchange column. Using this method, mono-, di- and tricarboxylic acids, aromatic acids and inorganic anions can be routinely separated in a single run. To avoid interferences from a variety of organic matrices, a sample preparation procedure based on solid-phase extraction has been devised in conjunction with this method.