Simultaneous Analysis of Carbonic ion and Seven Common Anions

Carbonate ion is contained in almost all aqueous samples and plays an important role for the ion balance. Therefore, simultaneous analysis of seven common anions (F^-,Cl^-, NO₂^-, Br^-, NO₃^-,PO₄^3-, SO₄^2-) together with carbonate ion can be considered as an important target for deveolpment. Previously there have been examples of analysis including a suppressed IC method using NaOH eluent and a non-suppressed IC method using, a polymethacrylate column, but they were not satisfactory enough in peak shape, peak separation and detection sensitivity. The present method uses IC SI-90 4E and allows the baseline separation of seven common anions together with carbonate ion by non-suppressed IC using the eluent, p-hydroxybenzoic acid, pH 8.2.

Sample :

		Standards	River ater(Water)
1.	F^-	2mg/L	0.066mg/L
2.	HCO₃^-	20mg/L	47mg/L
3.	Cl^-	3mg/L	9.6mg/L
4.	NO₂^-	5mg/L	-
5.	Br^-	10mg/L	-
6.	NO₃^-	10mg/L	9mg/L
7.	PO₄^3-	10mg/L	-
8.	SO₄^2-	10mg/L	12.4mg/L

Column       : Shodex IC SI-90 4E (4.0mmID*250mm)
Eluent       : ^*5mM p-hydroxbenzoic acid(pH8.2 ajusted by N,N-diethylethanolamine)
Flow rate    : 1.5mL/min
Detector     : Non-suppressed Conductivity
Column temp. : 25°C(room temp.)

*Add 0.69g of p-hydroxybenzoic acid in 1L messflask and fill pure water to approximately 90 mL. Add 720micro-L of N,N-diethylethanolamine followed by supesonification to complete dissolution. Fill water to 1L and use as the eluent after filtration.