Monovalent and Divalent Cation Standards (5) (Phosphoric Acid + 18-Crown 
    6-Ether Eluent)
With using IC 
YK-421, when Na
+ 
is contained so much in a sample, analysis of very small quantity of NH
4+ 
is difficult. Separation of Na
+ and NH
4+ 
is improved by adding 18-Crown 6-etherb in phosphate acid aqueous as eluent.

Sample : 20micro-L
1. 2mg/L 
Li+
2. 10mg/L 
Na+
3. 10mg/L 
NH4+
4. 20mg/L 
Ca2+
5. 10mg/L 
Mg2+
6. 20mg/L 
K+
Column       : Shodex IC YK-421 (4.6mmID*125mm)
Eluent       : (above); 4mM H3PO4 + 0.8mM 18-Crown 6-ether aq.
               (below); 4mM H3PO4 + 0.15mM 18-Crown 6-ether aq.
Flow rate    : 1.0mL/min
Detector     : Non-suppressed conductivity
Column temp. : 25deg-C