Abstract
Analytical potentialities of a chip‐based CE in determination of ammonium in wastewaters were investigated. CZE with the electric field and/or ITP sample stacking was performed on a column‐coupling (CC) chip with integrated conductivity detectors. Acetate background electrolytes (pH ∼3) including 18‐crown‐6‐ether (18‐crown‐6) and tartaric acid were developed to reach rapid (in 7–8 min) CZE and ITP‐CZE resolutions of ammonium from other cations (sodium, potassium, calcium and magnesium) present in wastewater samples. Under preferred working conditions (suppressed hydrodynamic flow (HDF) and EOF on the column‐coupling chip), both the employed methods did provide very good repeatabilities of the migration (RSD of 0.2–0.8% for the migration time) and quantitative (RSD of 0.3–4.9% for the peak area) parameters in the model and wastewater samples. Using a 900‐nL sample injection volume, LOD for ammonium were obtained at 20 and 40 μg/L concentrations in CZE and ITP‐CZE separations, respectively. Very good agreements of the CZE and ITP‐CZE determinations of ammonium in six untreated wastewater samples (only filtration and dilution) with the results obtained by a reference spectrometric method indicate a very good accuracy of both the CE methods presented.