Since the hydride generation (HG) method was first introduced by Holak 1 to atomic absorption spectrometry, HG-AAS has been widely used for the determination of arsenic in biological and environmental samples.2,3 As the HG-AAS method is based on the evolution and transport of arsine, careful optimization of experimental parameters and minimization of interferences are required for obtaining reliable results. 2 In the hydride generation procedure using tetrahydroborate(III), control of pH of the reduction solution was used to the differential determination of As(III) and As(V) 4-7 , based on the fact that As(III) can react with tetrahydroborate(III) at higher pH than As(V). Solvent extraction of As(III) followed by back-extraction procedure was also used before hydride generation. 8 Arsenic speciation procedures in environmental and biological samples by hydride generation followed by AAS, ICP-AAS and ICP-MS have been summarized in a review. 9 Many methods have also been reported for the determination of arsenic without hydride generation, such as neutron activation analysis 2,10 , voltammmetry 2,11 , spectrophotometry 12 , graphite-furnace atomic absorption spectrometry (GFAAS). 2,13-17 GFAAS is one of the most reliable techniques; in it, the loss of arsenic during the charing cycle of the graphite atomizer is prevented by matrix modification with salts of nickel or palladium. 2 The GFAAS procedure for the determination of trace amounts of arsenic was based on the solvent extraction followed by direct determination or determination after back extraction to an aqueous solution. Ammonium pyrrolidinedithiocarbamate (APDC) 13,15 , sbutyl dithiophosphate 14 and potassium iodide 16 were used for the selective extraction of As(III). Total arsenic(III,V) was then extracted after reduction of As(V) to As(III). The preconcentration of As(V) on a membrane filter as an ion associate of arsenomolybdate and tetraphenylphosphonium ions was also proposed; 17 in this, total As(III,V) was extracted after oxidation of As(III) to As(V).In a previous work we reported a solid phase extraction method using a finely divided ion-exchange resin and APDC for the GFAAS determination of trace amounts of cadmium and lead in water. 18 The advantages of the fine resin particles are: 1) they have hydrophilic properties and can be dispersed throughout the bulk solution in a short time; 2) they have a large surface area of hydrophobic properties and can rapidly extract the species of hydrophobic properties, regardless of the ionic strength of the bulk solution; 3) they can be collected on a membrane filter from the bulk solution by filtration and dispersed in a small volume of solution to make a suspension which is directly subjected to the GFAAS. In this work, a combination of finely divided ion-exchange resin and APDC was applied to preconcentration and GFAAS determination of trace amounts of arsenic in water. Department of Materials Science and Technology, Faculty of Science and Technology, Hirosaki University, Hirosaki 036, JapanA preconcent...

Graphite-furnace atomic absorption spectrometry (GFAAS) is one of the most widely used techniques for the determination of trace elements in water. However, its sensitivity for cadmium and lead is not sufficient for a direct determination of these elements in drinking water. So far, many techniques have been used for the enrichment of trace elements in water samples. One of the most important conditions of the enrichment techniques is simple connection to the subsequent determination techniques. When the desired trace elements can be quantitatively extracted on a small amount of fine particles, a method based on the collection of particles by filtration, the preparation of a suspension in a small volume and the determination by suspensionintroduction GFAAS is favorable. Chelating ionexchange resins 1-7 and ion-exchange resins 8 and activated carbon 9-12 with complexing agents have been used for this purpose. Another technique was recently reported in which a part of the resin thin layer was cut and inserted in a cuvette for the determination by electrothermal AAS. 13The aim of this work was to develop a simple preconcentration method for the determination of cadmium and lead in tap water with the combined use of a finely divided ion-exchange resin and APDC. Fine resin particles are well suited for the rapid collection of the desired trace elements from a large sample of aliquots. 8 Since the ion-exchange resin particles have both hydrophilic and hydrophobic properties, they can act as a hydrophilic organic solid in the bulk solution, and can extract species with hydrophobic properties. APDC was selected for the simultaneous extraction of cadmium and lead on the resin particles. The proposed method was applied to the determination of cadmium and lead in tap water supplied to our laboratory. Experimental ApparatusA Hitachi Zeeman-effect GFAAS (Model Z-8270) equipped with an auto-sampler (Model SSC-300) was used for measuring the atomic absorption of cadmium and lead. The instrumental operating conditions are summarized in Tables 1 and 2. A Toyo KG-25 filter holder with a membrane filter of cellulose nitrate (0.45 mm pore size, 25 mm in diameter) was used for collecting the resin particles by filtration under suction. A Branson Ultrasonic Cleaner B-42 was used for preparing the resin suspension. ReagentsAll reagents used were of analytical grade. A Yamato Model WAR-30 and a WB-21 Auto-Still were employed to purify the water used; the water was first passed through a reverse-osmosis membrane and then A rapid and simple preconcentration method based on the combined use of ammonium pyrrolidinedithiocarbamate (APDC) and a finely divided anion-exchange resin has been described for the determination of trace amounts of cadmium and lead by graphite-furnace atomic absorption spectrometry (GFAAS). Cadmium-and lead-APDC complexes were extracted simultaneously on the resin at pH 6. The resin particles holding the cadmium-and lead-APDC complexes were separated by filtration and dispersed in 1.0 ml of 0.1 mol l -1 hydrochloric ...

The enrichment of trace amounts of copper as complexes with various chelating agents was examined with the use of finely divided anion-and cation-exchange resins of the macroreticular type. Of the 16 chelating agents studied, bathocuproinedisulphonate (BCS) combined with the use of a finely divided anion-exchange resin was the most effective for the rapid enrichment of copper from large sample volumes. The resin particles holding the copper(1) -BCS complex were collected on a membrane filter and subsequently suspended in a small volume of 0.1 M hydrochloric acid. The resin suspension was then subjected to electrothermal atomisation atomic absorption spectrometry. The method was applied to the determination of copper in sea and river water samples and the results were compared with those obtained by densitometric measurement of the solid-state absorbance of the copper(1) -BCS complex in the resin phase.

It is well known that the vanadium compounds have the effects of lowering the elevated blood glucose, cholesterol and triglycerides in diabetic rats, 1 and that some marine organisms such as ascidians and fan worm accumulate vanadium in high concentrations. 2,3 Therefore, the development of the selective determination techniques for V(IV) and V(V) in natural water samples was an attractive topic for many researchers because vanadium is supposed to exist in quadrivalent or pentavalent state. [4][5][6][7][8][9][10][11] The conditions of sample storage are the critical points of the trace analysis. The loss of a desired element resulting from the adsorption on a container wall may occur when the sample solution was stored in the wrong conditions. Generally, the storage of the acidified sample solution (

No abstract