The problems in the anaysis using IC YK-421 is that the analysis of very small amount of NH₄⁺ in a sample which contains large amount of Na⁺ is difficult. Addition of 1.5 mM 18-Crown 6-ether in 5 mM Tartaric acid + 1 mM Dipicolinic acid + 1.5 g/L Boric acid eluent can solve the problem. Addition of crown 6-ether can adjust the elution volume of the cations. Especially, the elution volume of K⁺ is largely affected by the additon and elute after Mg²⁺.


Sample :
1. Li⁺
2. Na⁺
3. NH₄⁺
4. Ca²⁺
5. Mg²⁺
6. K⁺

Column       : Shodex IC YK-421 (4.6 mm I.D. x 125 mm)
Eluent       : 5 mM Tartaric acid + 1 mM Dipicolinic acid + 1.5 g/L Boric acid
               + 1.5 mM 18-Crown 6-ether aq.
Flow rate    : 1.0 mL/min
Detector     : Non-suppressed coductivity
Column temp. : 40 °C