Question

8. In reference to ion chromatography, indicate if the following statements are true (T) or false (F): A. Retention times are typically increased for large, multiply charged ions, due to increased ion-pairing interactions with the stationary phase. B. Following the adsorption of analytes to the stationary phase, the mobile phase is typically modulated from weak (OM NaCl) to strong (IM NaCl) elute compounds in order of their ion-pair interactions formed. C. The mobile phase has no role in altering or tuing separation selectivity.

Answer 1

Ion chromatography works based on the principle of physical adsorption of charged ionic compounds to the stationary phase of the column through ion-pairing interactions. Larger the concentration of ions and size stronger the physical adsorption and higher the retention of the ionic compound.

So,

A. Ture.

After the ionic adsorption of the analyte onto the stationary phase, the ionic strength could be modulated to weaken the electrostatic adsorption and release the analytes and elute from the column.

So,

B. True.

As we just discussed above, mobile phase ionic strength could be used to modulate the separation selectivity. Also, the pH of the mobile phase plays an important role in the separation selectivity.

So,

C. False.