Separation, preconcentration, and determination of cadmium in drinking waters.

A fast method for separation, preconcentration and determination of cadmium in drinking (source, well, tap) and water for irrigation is described. Iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)3, has the role of colloid precipitate flotation collector. The determination of cadmium in final water solutions preconcentrated by flotation can be performed by flame (FAAS) or electrothermal atomic absorption spectrometry (ETAAS). The method applied, either FAAS or ETAAS, depends of the concentration level of analyte in the water sample investigating. The AAS results are compared with inductively coupled plasma-atomic emission spectrometric measurements (ICP-AES) as an independent method. The ETAAS detection limit of cadmium is 0.002 microgram/L.

Preconcentration and separation of cadmium by use of cobalt(III) hexamethylenedithiocarbamate as a collector prior to its determination by atomic absorption spectrometry.

Co(III) hexamethylenedithiocarbamate has been applied as a collector in colloid flotation preconcentration of Cd from water prior to electrothermal atomic absorption spectrometry (ETAAS). All experimental parameters necessary for successful flotation have been studied and optimized. The ETAAS results were compared with those obtained by inductive coupled plasma-atomic emission spectrometry (ICP-AES). The ETAAS detection limit was found to be 0.003 microg L(-1) Cd.

Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation.

A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a colloid precipitate collector. The liquid-liquid extraction of Co, Cu, Pb and Ni is carried out by sodium diethyldithiocarbamate, NaDDTC, as complexing reagent into methylisobutyl ketone, MIBK. The electrothermal atomic absorption spectrometry (ETAAS) is used for determination of analytes. The detection limits of ETAAS followed by flotation are: 7.8 ng.g(-1) for Co, 17.1 ng.g(-1) for Cu, 7.2 ng.g(-1) for Pb and 9.0 mug.g(-1) for Ni. The detection limits of ETAAS followed by extraction are found to be: 12.0 ng.g(-1) for Co, 51.0 ng.g(-1) for Cu, 24.0 ng.g(-1) for Pb and 21.0 ng.g(-1) for Ni.

Determination of total thallium in fresh water by electrothermal atomic absorption spectrometry after colloid precipitate flotation.

Tl(I) and Tl(III) are preconcentrated simultaneously from aqueous solutions by colloid precipitate flotation using two collectors: hydrated iron(III) oxide (Fe(2)O(3).xH(2)O) and iron(III) tetramethylenedithiocarbamate (Fe(TMDTC)(3)). After the coprecipitation step and the addition of foaming agents, Tl(I) and Tl(III) were separated from the water by a stream of air bubbles. Various factors affecting Tl(I) and Tl(III) recoveries during the separation from water, including the collector mass, the nature of the supporting electrolyte, pH, zeta potential of the collector particle surfaces, type of tenside, etc., were investigated. Within the optimal pH range (6-6.5), establishing by a recommended procedure, Tl(I) and Tl(III) were separated quantitatively (94.9-100.0%) with 30 mg Fe(III). Both Tl ions were simultaneously separated without any previous conversion of one type of Tl ion to the other. Total Tl determination was performed by electrothermal atomic absorption spectrometry by previous matrix modification of the concentrated samples. The determination limit of Tl by this method is 0.108 mug l(-1).

Flame atomic absorption spectrometric determination of zinc after colloid precipitate flotation with hydrated iron(III) oxide and iron(III) tetramethylenedithiocarbamate as collectors.

Colloid flotation of zinc from fresh water with a combination of two collectors, hydrated iron(III) oxide (Fe(2)O(3).xH(2)O) and iron(III) tetramethylenedithiocarbamate (Fe(TMDTC)(3)), permits rapid separation of the precipitate before its atomic absorption spectrometric (AAS) analysis. All important parameters necessary for the successful flotation like optimal mass of collectors, pH of the medium, electrokinetic potential of the collector particle surfaces, type of tenside, induction time etc., were checked. At the optimal pH value of medium (5.5) establishing by recommended procedure, zinc was separated quantitatively (97.4-98.8%) with 5 mg Fe(III) as constitutive element of the two collectors used. The content of zinc was determined by flame atomic absorption spectrometry (FAAS). These results were compared with the results obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The FAAS detection limit for zinc is 9.4 mug 1(-1). The proposed method is simple, rapid and applicable to the zinc separation at mug 1(-1) levels from a large volume of water.