Chapter 5 Ion Measurement (F-53,55)5.3 Measurement Using Standard Addition Method68 HORIBAGeneral Cautions for Standard Addition MethodIn order to obtain more accurate and reliable data, pay attention to the following points:No ion of small coexisting tolerance limit." Effect of coexisting substance" page 230No interfering ions with a high selective coefficient should coexist.In the STANDARD ADDITION 2 and SAMPLE ADDITION 2 mode, the target ionconcentration in the sample and the electric potential slope of the ion electrodeare obtained with approximation formulas. Therefore, it is not necessary to per-form calibration or check the electric potential slope before measurement. How-ever, if the linearity of the ion electrode used is low, if the electric potential slopeis greatly different from the theoretical value (Nernst coefficient), or if a decreasein the concentration after addition is specified, then accurate measurementresults may not be obtained.5.3.1 Measuring Ion Concentration in Standard Addition 1 ModeThis mode is used to obtain the concentration of the ion species under measurement by addinga small amount of the target ions to the sample solution once, thus increasing the ionconcentration of the target component, and then measuring the change in electric potential atthat time.Setting the measurement mode1. In ION Measurement screen, pressF1 (ION SETUP).The ION SETUP screen appears.2. In the measurement item, pressor key, select the additionmethod, and then press theENTER key.3. Press F4 (RETURN).The ION Measurement screen (for theIon addition measurement) appears.4. Press or key to select (1)SINGLE of the known additionmethod, and press the ENTERkey.In performing the measurement by theaddition method, no setup for suchparameters, as Ion type, Electrode model,Electrode lot, and/or alarms.
