Effect of Pretreatment in The Analysis of Mineral Water

Samples containing more than 10mg/L of Mg²⁺ and/or 20mg/L of Ca²⁺ must be pretreated, because those divalent cations form complexes with the eleuent and give rise to broad peaks which interfere with the analysis. For pretreatment,samples are passed through a pretreatment cartridge packed Na⁺ type cation exchange resin. This replaces the divalent cations in samples by Na⁺ and removes the interferring peaks.


Sample : Mineral water (Water)
1. HCO₃^-
2. 6.7mg/L Cl^-
3. 4.4mg/L NO₃^-
4. 12mg/L SO₄^2-

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. : 25deg-C(Room temp.)

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