Determination Of Zinc In Sea Water Research Articles

Direct determination of zinc in seawater by graphite furnace atomic absorption spectrometry

Zinc in seawater was determined directly by graphite furnace atomic absorption spectrometry (GFAAS), using a stabilized temperature platform furnace (STPF) technique, and Zeeman background correction. Zinc in seawater was determined directly without modifier; the detection limit was 0.11 μg/1. Unpolluted seawater can be analyzed by this simple method generating results with high accuracy and precision. Significantly improved sensitivity and precision of the atomic signal were achieved when zinc in seawater was atomized from a graphite surface pretreated with vanadium (NH 4VO 3). With vanadium as modifier, the detection limit is decreased to 0.024 μg/l. The method of standard additions was used. The accuracy and precision of the developed methods were confirmed by analysis of certified reference saline waters.

Determination of Zinc in Seawater Using Flow Injection Analysis with Fluorometric Detection

A sensitive technique for the shipboard determination of zinc in seawater has been developed. The technique couples flow injection analysis with fluorometric detection (FIA-FL). A cation exchange column was used to separate zinc from interering alkali and alkaline earth ions and to concentrate Zn from seawarer. The organic indicator ligan, p-tosyl-8-aminoquinoline, was used to form a complex with zinc, the fluorescence of which was determined with a flow-through fluorometer. The deterction limit (defined as three times the standard deviation of the blank, n=4) was 0.1 nM for a 4.4-mL sample

Direct determination of zinc in sea-water using electrothermal atomic absorption spectrometry with Zeeman-effect background correction: effects of chemical and spectral interferences

The determination of zinc in sea-water using an electrothermal atomic absorption spectrometry system with Zeeman-effect background correction is presented. The influence of various chloride and nitrate salts on the atomization signal of zinc was examined. In chloride medium particularly, the interference effect induced through losses of zinc chloride, by the thermohydrolysis of magnesium chloride and simultaneous generation of HCl during the pyrolysis step is noted. In nitrate medium, zinc is more stabilized by Mg > Ca > Na > NH+4. The effect of various inorganic and organic acids, used as chemical modifiers, on the atomization of zinc and background absorption signals in sea-water were examined. In unmodified sea-water, a Zeeman interference effect related to the vaporization of the chloride matrix leading to a systematic under-compensation and consequently to erroneous zinc concentration values was observed. In sea-water, modified with 1 mol l–1 nitric acid, a spectral Zeeman interference effect induced by the Zeeman splitting of the absorption bands of NO molecules generated during the decomposition–reduction of nitrate was observed; the induced over-compensation is eliminated by selective pyrolysis at about 850 °C. The chemical interference effect (25%) is related to the simultaneous vaporization of zinc and sodium oxides; the detection limit (3σ) being about 80 ng l–1 for a 10 µl injected volume of sea-water. In sea-water modified with 0.7 mol l–1 oxalic acid, there is no significant interference effect and the detection limit in this medium is about 60 ng l–1 for a 10 µl injected volume of sea-water.

Rapid determination of zinc in seawater by column preconcentration/AAS.

Atomic absorption spectrometry with on-line chelating-resin column preconcentration has been applied to rapid determination of zinc in seawater. Filtered coastal seawater samples adjusted to pH 2.2 by adding 1 ml of conc. nitric acid against to 1 l of seawater was pumped at 6.0 ml min-1 and mixed with a stream of ammonium acetate buffer (pH 7) at 0.5 ml min-1. The sample was then passed through a microcolumn (3.2 mm i.d. 16 mm long) packed with Chelex-100 for 1 min. The column was washed with distilled water for 30 s and sequentially chelated zinc was eluted with about 160 μl of 2 M nitric acid at 3.0 ml min-1 for AAS determination. This method gave enhanced sensitivityof zinc by over 19 times better than that of a conventional AAS. The detection limit of the present method was 0.5 ppb (S/N=2). Precision of this method was 2.7% (R.S.D.) at the 10 ppb level of zinc aqueous standard. About 30 samples could be analyzed for 1 h. The present method was successfully applied to the rapid determination of zinc in seawater of Beppu Bay.

Selective spectrofluorimetric determination of zinc with benzyl 2-pyridyl ketone 2-quinolylhydrazone and its application to sea-water analyses

A method is described for the fluorimetric determination of zinc at the nanogram level, with benzyl 2-pyridyl ketone 2-quinolyl-hydrazone as fluorogenic complexing reagent. The reaction is done at pH 10.5–13.5, in aqueous ethanol medium (80% v/v ethanol). Of 43 foreign ions tested, only cadmium interferes seriously. The method has been applied to the determination of zinc in sea-water, after 25-fold concentration of the sample water.

Determination of zinc in sea-water by anodic stripping voltammetry

The horizontal distribution of zinc in surface waters from Guanabara Bay has been studied by use of optimized voltammetric techniques and ultraclean working procedures. The non-linearity observed between the peak current for zinc and the electrolysis time, as well as the appearance of a peak at −1.16 V, are discussed. The values found for total zinc in the samples range between 0.3 and 22 μg/l.

Direct determination of zinc in seawater by atomic absorption spectrophotometry

A direct atomic absorption spectrophotometric technique for the determination of total zinc in marine waters is described. The detection limit in a seawater matrix by this method is 2·10 -4 μg zinc, and 0.25-ml samples may be analysed without any pre-analysis preparation. Contamination problems are shown to be severe for zinc and initial attempts to evaluate the various chemical and physical forms present in natural water samples have had limited success.