The results presents the method validation. The method’s parameters determine for the validation were: selectivity, linearity, limit of detection, limit of quantification, precision and accuracy. The chromatographic columns plays an important role in the separation of chemical compounds. For this purpose, an IonPac AS-18 was chosen. This column have been described as being suitable for determination of low molecular weight organic acids like formic and acetic acids. IonPac AS Columns had been characterized in literature as having good results in separating formic and acetic acids and being able to determine this compounds in air samplers[8]. Along with the chromatographic column, the eluent concentration can make the difference between a good or an incomplete separation of the compound’s peaks. We started by testing different eluent concentrations on KOH, from 23mM to 2mM. In Figure 1 is presented the two carboxylic acids with eluent concentration of 23mM KOH. In this case, the resolution between the peaks is lower than 2 and, as can be seen, the peaks are not completely separated at the base.