Ion-chromatographic quantitation of fluoride and acetate - Statistical comparison of calibration curves from two similar eluents

Using a Dionex AS14 column and tightly controlled concentration ranges [center point+/-10 relative % (where the term 'relative %' refers to the quantity 'true minus predicted', divided by the true and multiplied by 100)], various calibration curves for hydrofluoric acid and acetic acid are generated and examined statistically. The curves are constructed for two Na2CO3-NaHCO3 mobile phases: (1)2.5 mM Na2CO3-3.4 mM NaHCO3, and (2) 0.1 mM Na2CO3-0.1 mM NaHCO3. With the former eluent, the two peaks an retained out of the void volume, but do not show baseline separation. Nearly complete resolution can be achieved with the weaker solution. However, peak shapes suffer and retention times lengthen. The overall goal is not to provide a completely validated method; rather, the aim is to provide the necessary statistical data for evaluating a calibration curve's acceptability. A Dionex DX 500 ion chromatograph and JMP statistical software were utilized for the study. (C) 1998 Elsevier Science B.V.