ORGANIC-ACID ANALYSIS BY ION CHROMATOGRAPHY PARTICLE-BEAM MASS-SPECTROMETRY

Ion chromatography-mass spectrometry (IC-MS) has been investigated, us ing the particle beam interface, as an analytical technique for the an alysis of weak organic acids. Ion-exclusion chromatography is a techni que for separating weak acids. Using dilute HCI as the mobile phase, w eak acids are separated on a cation-exchange resin. IC-MS was used to detect and identify weak acids in commercial grape juices and red wine . Analyses were performed using both electron (EI) and chemical ioniza tion (CI). Isobutane CI readily produced protonated molecular ions, an d combined with structural information obtained from EI analyses, iden tification of weak acids was possible. A main advantage of this techni que is that co-eluting acids can be identified, whereas with conductiv ity and UV detection this is difficult. To simplify these analyses, so lid-phase extraction was used to remove sugars from the juice and wine samples.