Determination of trace labile copper in environmental waters by magnetic nanoparticle solid phase extraction and high-performance chelation ion chromatography

• Sub-ppb quantitation of dissolved copper in environmental waters.
• Coupling of magnetic nanoparticle extraction and chelation ion chromatography.
• Amenable to analysis of estuarine and coastal seawater samples.

Cobalt magnetic nanoparticles surface functionalised with iminodiacetic acid were evaluated as a nano-particulate solid phase extraction absorbent for copper ions (Cu2+) from environmental water samples. Using an external magnetic field, the collector nanoparticles could be separated from the aqueous phase, and adsorbed ions simply decomplexed using dilute HNO3. Effects of pH, buffer concentration, sample and sorbent volume, extraction equilibrium time, and interfering ion concentration on extraction efficiency were investigated. Optimal conditions were then applied to the extraction of Cu2+ ions from natural water samples, prior to their quantitation using high-performance chelation ion chromatography. The limits of detection (LOD) of the combined extraction and chromatographic method were ~0.1 ng ml−1, based upon a 100-fold preconcentration factor (chromatographic performance; LOD=9.2 ng ml−1 Cu2+), analytical linear range from 20 to 5000 ng mL−1, and relative standard deviations=4.9% (c=1000 ng ml−1, n=7). Accuracy and precision of the combined approach was verified using a certified reference standard estuarine water sample (SLEW-2) and comparison of sample determinations with sector field inductively coupled plasma mass spectrometry. Recoveries from the addition of Cu2+ to impacted estuarine and rain water samples were 103.5% and 108.5%, respectively. Coastal seawater samples, both with and without prior UV irradiation and dissolved organic matter removal were also investigated using the new methodology. The effect of DOM concentration on copper availability was demonstrated.

Cobalt magnetic nanoparticles functionalised with iminodiacetic acid have been used with high-performance chelation ion chromatography for trace copper quantitation in complex environmental waters.Figure optionsDownload as PowerPoint slide