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 eluent 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 interfering peaks.
(Pretreatment with the cartridges packing Na+ type cation exchange resin)
1. Rinse the cartridge with 3mL of methanol and 3mL of H2O separately.
2. Load 3mL of the sample onto the cartridge.
3. Waste 1mL of the first elution.
4. Collect 2mL of following elution.
Sample : Mineral water, 100μL
Column : Shodex IC SI-90 4E (4.0mmI.D. x 250mm) Eluent : 5mM p-Hydroxybenzoic acid + 5.3mM N,N-Diethylethanolamine aq. Flow rate : 1.5mL/min Detector : Non-suppressed conductivity Column temp. : 25°C