Tap Water (1) (YK-421)

Cations in tap water were analyzed using IC YK-421. At present, ion chromatogaraphy is not used for in Japanese regulations for tap water. However, ion chromatography is very useful method for the simultaneous analysis of monovalent and divalent cations such as Na⁺, K⁺ and Mg²⁺.

Sample : 15micro-L

No.	Cations	std.	Tap water (Water)
1	Li⁺	2mg/L	-
2	Na⁺	10mg/L	11.70mg/L
3	NH₄⁺	10mg/L	-
4	K⁺	20mg/L	1.76mg/L
5	Ca²⁺	20mg/L	16.40mg/L
6	Mg²⁺	10mg/L	4.80mg/L

Cations	Current regulation	Analyses by Shodex IC YK-421
		Detection limit (S/N=3)	Reproducibility(N=5)
		Detection limit (S/N=3)	Mean value	CV(%)
Na⁺	less than 200mg/L (Flameless atomic adsorption spectrophptometory or ICP)	Na⁺ 1.5 micro-g/L	11.3mg/L	1.2
Ca²⁺	less than 300mg/L (Titration method)	Ca²⁺ 3.0 micro-g/L	15.2mg/L	0.95
Mg²⁺	less than 300mg/L (Titration method)	Mg²⁺ 1.5 micro-g/L	4.9mg/L	1.5

Column       : Shodex IC YK-421 (4.6mmID*125mm)
Eluent       : 5mM Tartaric acid + 1mM Dipicolinic acid + 1.5g/L Boric acid aq.
Flow rate    : 1.0mL/min
Detector     : Shodex CD
Column temp. : 40°C