Determination of Cadmium and Lead in Tap Water by Graphite-Furnace Atomic Absorption Spectrometry after Preconcentration on a Finely Divided Ion-Exchange Resin as the Pyrrolidinedithiocarbamate Complexes

Abstract

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 ...

Determination of Phenol in Tap Water and River Water Samples by Solid-Phase Spectrophotometry

“…An anion-exchange resin suspension (ARS) was prepared from a macroreticular type Diaion WA30 (Mitsubishi Kagaku, Tokyo, Japan) according to the reported method. 27 The exchange capacity of the resin suspension was 15.7 µeq cm -3 .…”

Determination of Tin by Resin-Suspension Electrothermal Atomic Absorption Spectrometry after Enrichment as the Complex with Ammonium Pyrrolidinedithiocarbamate

“…An anion exchange resin suspension (ARS) was prepared from a Diaion PA316 (Mitsubishi Kagaku, Tokyo, Japan) according to the reported method. 13 The exchange capacity of the resin suspension was 10.2 μeq ml −1 .…”

“…Solid analysis by ETAAS, in which a solid sample is placed directly in a furnace or a sample prepared as a slurry or a suspension is injected to a furnace, has been widely used, as summarized in the monograph 1 and the reviews. 2,3 The methods have substantially been applied for the determination of trace elements in solid samples, such as soil, sediment and sludge, however, they have also been applied to water samples after preconcentration of the desired trace element in the precipitate 4,5 or on fine particles such as chelating resins, [6][7][8] activated carbon, 9,10 ion-exchange resins, [11][12][13][14][15] and cobalt(III) oxide. 16,17 So far, a solid sampling procedure was applied to the determination of tin in natural water, 5 in which the tin was preconcentrated by coprecipitation with a Ni-APDC complex and a part of the precipitate was packed in a miniature cup for ETAAS analysis.…”

PRECONCENTRATION OF Cd2+ IN DIFFERENT SAMPLES BY CHEMICALLY MODIFIED SIO2-DHAQ NANOPARTICLES

“…preconcentration is usually necessary prior to the determination of the metals. [2][3] Nowadays, liquid-liquid extraction [4][5][6] , ion-exchange resins 7 and solid-phase extraction [8][9] are used for the preconcentration of different metal ions. Of all these methods, solid phase extraction has been widely used since it is simple, rapid and inexpensive, less polluting to the environment and can be easily automated.…”