Evaluation of Select Variables in the Ion Chromatographic Determination of F−, Cl−, Br−, NO3−, SO4−2, and PO4−3 in Serum Samples

A full experimental design at two levels is applied for the estimation of the significance of select factors that may influence the ion chromatography (IC) determination of F−, Cl−, Br−, NO3−, SO4−2, and PO4−3 in serum samples. The factors studied are various sample deproteinization procedures, eluent composition, and flow rates. Deproteinization using either acetonitrile-NaOH or ultrafiltration can be used in order to obtain a significant protein removal before IC analysis; however, the former is recommended because it is less time-consuming and cheaper. Better resolution is obtained when a sodium hydroxide solution is used as the eluent. There is no influence of the sample's deproteinization procedures on the chromatographic resolution.