Pre-concentration technique of zinc and copper in water employing dithizone functionalized strong anionic exchange SPE cartridges

Background: A simple, selective and rapid method for determining trace amounts of Cu and Zn in water samples using flame atomic absorption spectrophotometry (FAAS) was investigated.

Objective: The objective of this study was to evaluate the efficiency of dithizone functionalized strong anionic exchange (SAX) pre-packed SPE cartridges for pre-concentration of Znand Cu in water samples, prior to analysis by Flame Atomic Absorption Spectrophotometry (FAAS). This is by focusing on the optimization of recoveries of Zn and Cuin water at varied conditions of pH, volume of sample and eluting solvent.

Materials and Methods: Pre-concentration of metals was by Solid Phase Extraction (SPE) employing dithizone functionalized strong anionic exchange pre-packed cartridges (SAX SPE). Recoveries on SPE were optimized by varying several parameters including pH, volume of sample, volumes of HCl used as eluting solvent and effect of co-retained metal ions.

Results: Recoveries for the unmodified SAX SPE cartridge were 11.41% and 12.90% for Cu and Zn at pH 7.4, when the sample and eluting volumes were 100 mL and 15 mL respectively. The dithizone functionalized SPE when compared to unmodified SPE had improved recoveries for Cu (31.60%) and Zn (29.00%) at optimized conditions of pH 7.4, sample volume, 100 ml, while the eluent volume (HCl) was 20 and 25 mL respectively. The technique of functionalizing SAX pre-parked SPE with dithizone resulted in improved recoveries.

Conclusion: This method could be of great potential for determination of Cu and Zn in water samples, hence warrants further investigation.