One-shot flow injection spectrophotometric simultaneous determination of copper, iron and zinc in patients’ sera with newly developed multi-compartment flow cell

Online preconcentration and determination of trace amounts of zinc in nature waters

A simple, sensitive, reliable and flexible flow injection spectrophotometric method is proposed for on-line preconcentration and determination of trace amounts of zinc in water. At the presence of Tween-80 in pH 9.3 buffer solutions, the shade of color of Zn (II)-PAN complex is in a linear relation to the zinc amount at the point of the maximum absorption peak of 560 nm. The optimal experimental conditions, including reaction conditions and preconcentration conditions, had been obtained. The linear range of the proposed method was between 2.0 and 360 mug L(-1) and the detection limit was 0.42 mug L(-1). The relative standard deviation was 3.55% and 2.14% for 5.0 mug L(-1) and 50 mug L(-1) of zinc standard solution (n = 8). The method had been successfully applied to zinc determination in water samples and the analytical results were satisfactory.

High-performance liquid chromatography with sequential injection for online precolumn derivatization of some heavy metals

HPLC was coupled with sequential injection (SI) for simultaneous analyses of some heavy metals, including Co(II), Ni(II), Cu(II), and Fe(II). 2-(5-Nitro-2-pyridylazo)-5-[N-propyl-N-(3-sulfopropyl)amino]phenol (nitro-PAPS) was employed as a derivatizing reagent for sensitive spectrophotometric detection by online precolumn derivatization. The SI system offers an automated handling of sample and reagent, online precolumn derivatization, and propulsion of derivatives to the HPLC injection loop. The metal-nitro-PAPS complexes were separated on a C(18)-muBondapak column (3.9x300 mm(2)). Using the proposed SI-HPLC system, determination of four metal ions by means of nitro-PAPS complexes was achieved within 13 min in which the parallel of derivatization and separation were processed at the same time. Linear calibration graphs were obtained in the ranges of 0.005-0.250 mg/L for Cu(II), 0.007-1.000 mg/L for Co(II), 0.005-0.075 mg/L for Ni(II), and 0.005-0.100 mg/L for Fe(II). The system provides means for automation with good precision and minimizing error in solution handling with the RSD of less than 6%. The detection limits obtained were 2 microg/L for Cu(II) and Co(II), and 1 microg/L for Ni(II) and Fe(II). The method was successfully applied for the determination of metal ions in various samples, including milk powder for infant, mineral supplements, local wines, and drinking water.

Continuous flow analysis combined with a light-absorption ratio variation approach for determination of copper at ng/ml level in natural water

The complexation between Cu(II) and naphthochrome green (NG) is very sensitive at pH 4.09 with the formation of complex ion [Cu(NG)2(H2O)2](2-). It can thus used for the determination of Cu(II) by the light-absorption ratio variation approach (LARVA) with a good selectivity. Both the ordinary detection procedure and continuous flow analysis (CFA) were carried out, where the latter is fit for continuous and rapid analysis of samples. The limit of detection (LOD) of Cu(II) is only 1 ng/ml, which is favorable for direct monitoring of natural water. About 30 samples could be analyzed per hour by CFA. Cu(II) contents in Yangtze River, West Lake, Taihu Lake of China and seawater near Shanghai were determined with satisfactory results. The CFA-LARVA spectrophotometry was the first to be coupled and it will play an important role in the in-situ analysis of natural water quality.