Column chromatographic pre-concentration of iron(III) in alloys and biological samples with 1-nitroso-2-naphthol-3,6-disulphonate and benzyldimethyltetradecylammonium-perchlorate adsorbent supported on naphthalene using atomic absorption spectrometry

The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples.     

Atomic absorption spectrometric determination of trace zinc in alloys and biological samples after preconcentration with [1-(2-pyridylazo)-2-naphthol] on microcrystalline naphthalene

An atomic absorption spectrometric method for the determination of trace amounts of zinc after adsorption of its [1-(2-pyridylazo)-2-naphthol] complex on microcrystalline naphthalene has been developed. This complex is adsorbed on microcrystalline naphthalene in the pH range 3.5-7.5 from large volumes of aqueous solutions of various alloys and biological samples with a preconcentration factor of 40. After filtration, the solid mass consisting of the zinc complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Zinc can alternatively be quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. About 0.5 ng of zinc can be concentrated in a column from 200 ml of aqueous sample, where its concentration is as low as 2.5 pg ml-1. The calibration curve is linear in the range 0.1-6.5 ng ml-1 in dimethylformamide solution. Eight replicate determinations of 2 ng ml-1 of zinc gave a mean absorbance of 0.145 with a relative standard deviation of 1.5%. The sensitivity for 1% absorption was 0.061 ng ml-1. Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of zinc, have been studied in detail to optimize the conditions for the determination of zinc in various standard complex materials.     

Preconcentration of trace cobalt with the ion pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and tetraphenylborate onto microcrystalline naphthalene or column method and its determination by derivative spectrophotometry

Cobalt-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-tetraphenylborate ion associated complex is quantitatively adsorbed on microcrystalline naphthalene in the pH range 3.5-9.5 from a fairly large volume of the aqueous samples (preconcentration factor ~30). After filtration, the solid mass consisting of the cobalt complex and naphthalene was dissolved with 5 ml of dimethylformamide (DMF) and the metal determined by first-derivative spectrophotometry. The cobalt-5-Br-PADAP complex can alternatively be quantitatively retained on ammonium tetraphenylborate-naphthalene adsorbent filled in a column (preconcentration factor 120) in the same pH range and determined similarly. The detection limit is 30 ppb (signal-to-noise ratio=2) and the calibration curve is linear over 0.3-8.0 mug of cobalt in 5 ml of the final DMF solution. Eight replicate determinations of 1.0 mug of cobalt gave a mean peak height of 0.208 (at 611.5 nm) with a relative standard deviation of 1.2%. The sensitivity of the method is 1.04 (dA/dnm) ml mug(-1) found from the slope of the calibration curve. The interference of a large number of anions and cations on the determination of cobalt has been studied and the optimized conditions developed were utilized for its trace determination in various standard alloys and biological samples.     

Column preconcentration of titanium in aluminium and zinc alloys with oxalic acid-ascorbic acid and the ion-pair of sodium 1,2-dihydroxybenzene-3,5-disulphonic acid and tetradecyldimethylbenzylammonium chloride supported on naphthalene using spectrometry

A solid ion-pair compound produced from sodium 1,2-dihydroxybenzene-3,5-disulphonic acid (Tiron) and tetradecyldimethylbenzylammonium chloride(TDBA) supported on naphthalene in a simple glass-tipped funnel tube provides a simple adsorbent system for preconcentrating titanium from some alloys. Titanium reacts with Tiron to form a water-soluble coloured chelate anion which in turn forms a water-insoluble stable titanium/Tiron/TDBA complex with the ion-pair on the surface of naphthalene packed in a column. Titanium is quantitatively retained on the naphthalene in the presence of L-ascorbic acid and oxalic acid in the pH range 3.0-4.5 and at a flow-rate of 1 mil/min. The metal complex and naphthalene were dissolved from the column with 5 ml of dimethylformamide(DMF), and the absorbance of the solution was measured at 398 nm. A calibration graph was linear over the range 1-18 mug of titanium in 5 ml of the final DMF solution. The complex has a molar absorptivity of 1.39 x 10(4) l.mole(-1).cm(-1) and a sensitivity of 3.44 x 10(-3) mug/cm(2) for 0.001 absorbance. Eight replicate determinations for a sample containing 12 mug of titanium gave a mean absorbance of 0.697 with a relative standard deviation of 0.82%. The interference of various ions was studied and optimum conditions were developed for the determination of titanium in various aluminium and zinc alloys.     

Tetradecyldimethylbenzylammonium thiocyanate adsorbent supported on naphthalene for the preconcentration and determination of cobalt in aluminium alloys and steels using atomic absorption spectrometry

A solid ion-pair material produced from tetradecyldimethylbenzylammonium chloride (TDBA) and ammonium thiocyanate on naphthalene provides a simple, rapid and selective technique of preconcentrating cobalt from up to 200 ml of aqueous solution. Cobalt reacts with sodium 1-nitroso-2-naphthol-3,6-disulphonate (nitroso-R salt) to form a brown, water-soluble chelate anion. The chelate anion forms a water-insoluble Co-nitroso-R salt-TDBA complex on naphthalene packed in a column and trace cobalt is quantitatively retained on the naphthalene in the pH range 2.7–11.0 at a flow-rate of 2 ml min^?1. The solid mass is stripped from the column with 5 ml of dimethylformamide (DMF) and cobalt is measured by atomic absorption spectrometry (AAS) at 241 nm. The calibration graph is linear over the concentration range 0.5–15μg Co in 5 ml of dimethylformamide solution. Seven replicate determinations of 9 μg of cobalt gave a mean absorbance of 0.095 with a relative standard deviation of 1.7%. The sensitivity for 1% absorption was 0.0834μg ml^?1 (0.240 μg ml^?1 for direct AAS on the aqueous solution). The proposed method was utilized for the determination of cobalt in standard aluminium alloys and steel samples.     

Derivative spectrophotometric determination of iridium after preconcentration of its 1-(2-pyridylazo)-2-naphthol complex on microcrystalline naphthalene

Iridium is preconcentrated from the large volume of its aqueous solution using 1-(2-pyridylazo-2-naphthol) (PAN) on microcrystalline naphthalene in the pH range of 4.5-6.0. The solid mass after filtration is dissolved with 5 ml of dimethylformamide (DMF) and the metal determined by first derivative spectrophotometry. The detection limit is 20 ppb (signal to noise ratio = 2) and the calibration curve is linear over the concentration range 0.25-75.0 mug in 5 ml of the final DMF solution with a correlation coefficient of 0.9996 and relative standard deviation of +/- 1.1%. Various parameters such as the effect of pH, volume of aqueous phase, choice of solvent, reagent and naphthalene concentration, shaking time and interference of a number of metal ions on the determination of trace amount of iridium have been studied in detail to optimize the conditions for its determination in synthetic samples corresponding to various standard alloys and environmental samples.     

Flame atomic absorption spectrometric determination of trace amounts of manganese in alloys and biological samples after preconcentration with the ion pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and ammonium tetraphenylborate on microcrystalline naphthalene or by column method.

Manganese is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 7.5-10.5 from large volumes of aqueous solutions of various samples. After filtration, each solid mass consisting of the manganese complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Manganese complex can alternatively be quantitatively adsorbed on ammonium tetraphenylborate-naphthalene adsorbent packed in a column and determined similarly. About 0.1 microgram of manganese can be concentrated in a column from 500 ml of aqueous sample, where its concentration is as low as 0.2 ppb. Eight replicate determinations of 1.0 ppm of manganese gave a mean absorbance of 0.224 with a relative standard deviation of 1.8%. The sensitivity for 1% absorption was 19 ppb. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of manganese in various standard samples.     

Ammonium tetraphenylborate-naphthalene adsorbent for the preconcentration and trace determination of iron in alloys and biological samples using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol by third derivative spectrophotometry

A solid ion-pair material produced from ammonium tetraphenylborate on naphthalene (ATPB-naphthalene) provides a simple, rapid, economical and selective technique for preconcentrating iron from approximately 500 ml of aqueous solution of standard alloys and biological samples. Iron reacts with 2-(5-bromo-2-pryidlazo)-5-diethylaminophenol (5-Br-PADAP) to form a water-soluble cationic complex. When the aqueous solution of this cationic species in the pH range 3.2-8.5 is passed over the adsorbent ATPB-naphthalene at a flow rate of 1 ml min(-1), it is quantitatively retained on naphthalene as an uncharged ion-associated complex. The solid mass from the column was dissolved out with 5 ml of dimethylformamide (DMF) and iron is determined by third derivative spectrophotometry by measuring the signal d(3)A/ dlambda(3) between lambda(2)(773 nm) and lambda(3)(737 nm). The calibration curve is linear over the concentration range 0.10-25.0 mug of iron in 5 ml of DMF solution. Eight replicate determinations of 5 mug of iron gave a mean intensity (peak-to-peak signal between lambda(2) and lambda(3)) of 1.534 with a relative standard deviation of 0.90%. The sensitivity of the method is 0.307 (d(3)A/dnm(3) )/mug found from the slope of the calibration curve. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of iron in various standard alloys and biological samples.     

Spectrophotometric determination of copper in environmental samples by solid-liquid extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene

A fairly selective and sensitive spectrophotometric method has been developed for determination of copper after extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene in the pH range of 6.1-8.4. At room temperature, the solid naphthalene containing the metal complex is separated by filtration, dissolved in dimethylformamide (DMF) and the absorbance measured at 470 nm against the reagent blank. Beer's law is obeyed in the concentration range, 0.0-9.6 micrograms of copper in 10ml of DMF. The molar absorptivity and sensitivity are 6.30 X 10(4) 1 mol-1 cm-1 and 0.001 micrograms cm-2, respectively. The interference of various ions has been studied and the method has been applied for the determination of copper in various standard reference materials, beers, wines, human hair and environmental samples.     

A simple flow injection spectrophotometric determination of nitrite based on its reaction with thiourea.

A simple flow injection spectrophotometric method for the determination of nitrite is described. Nitrite injected into the flow system reacts with thiourea in acidic medium and the generated thiocyanate ion reacts with Fe(III) in the reagent solution to produce a highly colored product. The influences of chemical and physical parameters including reagent concentrations, sample volume injected, flow rates of the carrier and reagent solutions, reaction coil length and reaction temperature, were studied and optimum values of these parameters were established. Under the optimum conditions, the calibration curve for nitrite was linear over the concentration range 0.36 - 90 microg ml(-1) without preconcentration and over the range 3.8 - 500 ng ml(-1) with a simple online preconcentration step using an anion exchange column. The corresponding detection limits were 0.36 micro ml(-1) and 3.8 ng ml(-1), respectively. Up to 25 samples can be analyzed per hour, with an average relative standard deviation of < or = 1.2%. Interferences by various foreign ions were studied and the method was applied to the determination of nitrite in water and spiked water samples.     

Determination of manganese by flame atomic absorption spectrometry after its adsorption onto naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN)

A system for determination of manganese, after preconcentration with 3% (w/w) 1-(2-pyridylazo)-2-naphthol (PAN), adsorbed on microcrystalline naphthalene is proposed. An amount of 200 mg of this complexing mixture is placed in a glass column and conditioned with a NH₄Cl/NH₄OH buffer solution (pH 9.5). The aqueous sample, containing manganese, is treated with an ammonium tartrate solution, then with a hydroxylammonium chloride solution and, finally, with a buffer solution. The resulting solution is passed through the column containing microcrystalline naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN) where Mn(II) is retained. The column is first washed with deionized water and then with 10.0 ml of dimethylformamide to dissolve the Mn(II)-PAN/naphthalene complex. Manganese is determined by air-acetylene flame atomic absorption spectrometry. About 1 μg of manganese can be concentrated from 200 ml of aqueous sample, allowing a preconcentration factor of 20, a limit of quantification of 5 ng ml⁻¹ and R.S.D. of 3.8%. The accuracy was ascertained using certified reference materials, including samples of urine and glass. Water samples were also analysed and the results are in good agreement with those obtained by graphite furnace atomic absorption spectrometry.     

Preconcentration of trace nickel with the ion pair of disodium 1-nitroso-2-naphthol-3,6-disulfonate and tetradecyldimethylbenzylammonium chloride on microcrystalline naphthalene or by the column method and determination by third derivative spectrophotometry

Nickel is quantitatively retained by disodium 1-nitroso-2-naphthol-3,6-disulfonate (nitroso-R salt) and tetradecyldimethylbenzylammonium chloride (TDBA(+)Cl(-)) on microcrystalline naphthalene in the pH range 5.4-12.1 from large volumes of aqueous solutions of various alloys and biological samples. After filtration, the solid mass consisting of the nickel complex and naphthalene was dissolved with 5 ml of dimethylformamide (DMF) and the metal was determined by third derivative spectrophotometry. Nickel complex can alternatively be quantitatively adsorbed on tetradecyldimethylbenzylammonium-naphthalene adsorbent packed in a column and determined similarly. The detection limit is 10 ppb (signal to noise ratio 2) and the calibration curve is linear from 30 to 5.4x10(3) ppb in dimethylformamide solution with a correlation coefficient of 0.9997 by measuring the distance d(3)A/dlambda(3) between lambda(1) (537 nm) and lambda(2) (507 nm). Eight replicated determinations of 2.5 mug of nickel in 5 ml of dimethylformamide solution gave a mean intensity (peak-to-peak signal between lambda(1) and lambda(2)) of 0.339 with a relative standard deviation of +/-0.87%. The sensitivity of the method is 0.677 ml/mug found from the slope (d(3)A/dnm(3)) of the calibration curve. Various parameters such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of nickel has been studied in detail to optimize the conditions for nickel determination in various alloys and biological samples.     

High-performance liquid chromatographic determination of cefonicid in human plasma and urine

A high-performance liquid chromatographic assay for determination of cefonicid concentrations in human plasma and urine samples has been developed using cefazolin as an internal standard. For the analysis of plasma samples two calibration curves were utilized covering the cefonicid concentration ranges of 0.05-1.0 microgram/ml and 1.0-50.0 micrograms/ml, respectively. Coefficients of variation of 7.4% or less were obtained for cefonicid concentrations of 0.05-50.0 micrograms/ml. Mean bias was +6.0% at 0.05 micrograms/ml cefonicid and between -2.1% and +1.6% for 1.0-50.0 micrograms/ml cefonicid. Plasma samples containing 30 ng/ml cefonicid could be well distinguished from blank plasma samples. Urine samples were analysed by using a calibration curve for cefonicid concentrations between 1.0 and 50.0 micrograms/ml. ranged from 8.6% at a cefonicid concentration of 1.0 microgram/ml to 0.5% at 50.0 micrograms/ml with a mean bias between -3.0% and +0.3%.     

Column Preconcentration of Aluminum and Copper(II) in Alloys, Biological Samples, and Environmental Samples with Alizarin Red S and Cetyltrimethylammonium-Perchlorate Adsorbent Supported on Naphthalene Using Spectrometry

A column method has been established for the preconcentration of aluminum and copper(II) with Alizarin Red S and a cetyltrimethylammonium-perchlorate ion pair supported on naphthalene, using a simple glass-tipped tube. Aluminum and copper(II) react with Alizarin Red S to form water-soluble colored chelate anions. These chelate anions form water-insoluble ternary complexes with the adsorbent on the inactive surface of naphthalene packed into a column. They are quantitatively retained in the pH ranges of 4.7-5.2 for aluminum and 5.0-10.0 for copper. The solid mass is dissolved out from the column with 5 ml of dimethylformamide (DMF) for aluminum and 5 ml of ethanol for copper and the absorbance was measured with a spectrometer at 525 nm for aluminum and at 529 nm for copper. The calibration curves were linear over the concentration ranges of 0.25-5.0 μg of aluminum in 5 ml of DMF solution and 0.50-12.0 μg of copper in 5 ml of ethanol solution. The molar absorptivities and Sandell′s sensitivities were respectively calculated to be 2.8 × 10⁴ liter · mol⁻¹ · cm⁻¹ and 9.62 × 10⁻⁴ μg · cm⁻² for aluminum and 2.5 × 10⁴ liter · mol⁻¹ · cm⁻¹ and 2.5 × 10⁻³ μg · cm⁻² for copper. Seven replicate determinations of sample solutions containing 2.5 μg of aluminum and 6.0 μg of copper gave mean absorbances of 0.520 and 0.480 with relative standard deviations of 1.67 and 0.33%, respectively. Interference due to various foreign ions has been studied and the method has been applied to the determination of aluminum in standard alloys, tea leaves, vehicle particulates, copper in coal fly ash, and commercial salt samples.     

Determination of trace levels of manganese in various biological and environmental samples by atomic absorption spectrometry after solid-liquid extraction and preconcentration with the ion pair formed by the nitroso-S anion and the tetradecyldimethylbenzylammonium cation.

Manganese is quantitatively retained by 2-nitroso-1-naphthol-4-sulfonic acid (nitroso-S) and tetradecyldimethylbenzylammonium (TDBA) chloride on microcrystalline naphthalene in the pH range 9.5-10.6 from large volumes of aqueous solutions of various samples. After filtration, the solid mass consisting of the manganese complex and naphthalene is dissolved in 5 mL dimethylformamide and the metal is determined by flame atomic absorption spectrometry. Alternatively, the manganese complex can be quantitatively adsorbed on TDBA-naphthalene adsorbent packed in a column and determined similarly. About 0.2 microg manganese can be concentrated in a column from 400 mL aqueous sample with a concentration as low as 0.5 ng/mL. Eight replicate determinations of manganese at 0.8 microg/mL gave a mean absorbance of 0.156 for the final solution with a relative standard deviation of 1.4%. The sensitivity for 1% absorption was 23 ng/mL. The interference of a large number of anions and cations was studied, and the optimized conditions developed were used for trace determinations of manganese in various alloys, and in biological and environmental samples.     

Ammonium tetraphenylborate-naphthalene adsorbent for the preconcentration and trace determination of uranium in standard alloys and synthetic samples using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol by fourth-derivative spectrophotometry

A solid ion-pair material produced from ammonium tetraphenylborate (ATPB) and naphthalene has been used for the preconcentration of uranium from the large volume of its aqueous complex samples. Uranium reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) to form a water insoluble, coloured complex. This complex is quantitatively retained on the ATPB-naphthalene adsorbent filled in a column in the pH range 7.0–9.5 and at a flow rate of 2 ml/min. The solid mass from the column is dissolved with 5 ml of dimethylformamide (DMF) and uranium is determined by fourth-derivative spectrophotometry. The calibration curve is linear over the concentration range of 0.13–15.0 g of uranium in 5 ml of the final DMF solution. Seven replicate determinations of 6 g of uranium gave a mean peak height (peak-to-peak signal between 592 nm and 582 nm) of 1.02 with a relative standard deviation of 0.95%. The sensitivity is 0.8419 (d⁴A/d⁴)/(g ml^–1) found from the slope of the calibration curve. The interference of a large number of anions and cations on the estimation of uranium has been studied and the method applied for the determination of uranium in coal fly ash, Zr-base alloy and some synthetic samples corresponding to standard alloys.     

Column Chromatographic Preconcentration of Copper in Alloys and Complex Materials Using 9,10 Phenanthrenequinone Monoxime Supported on Naphthalene

Abstract

A solid chelating compound phenanthrenequinone monoxime PQM) supported on naphthalene provides a rapid and economical means of preconcentration and separation of copper from the aqueous samples. Copper forms a complex with PC:: supported on naphthalene in the column at pH 6.1–8.4 with a flow rate of 1 ml/min. The metal complex and naphthalene are dissolved out from the column with 5 ml of DMF and the absorbance is measured at 470 nm against reacent blank. Beer's law is obeyed in the concentration range 0.6 9.6 μg of copper in 5 ml of DMF. The molar absorptivity and sensitivity are 6.3×10⁴ L mol^?1 cm^?1 and 0.001 μg cm^?2 respectively.     

Determination of beta-lactams and their biosynthetic intermediates in fermentation media by pre-column derivatisation followed by fluorescence detection

This paper describes a novel and sensitive pre-column derivatisation method for the detection and quantitation of beta-lactams and their biosynthetic precursors at trace levels in fermentation media. Filtered broths from fermentations of strains of Penicillium chrysogenum and Cephalosporium acremonium, after deproteination and centrifugation, were incubated with 9-fluorenylmethylchloroformate for 5 min at 20 degrees C in 0.2 M borate buffer at pH 7.7. Following two-fold pentane extraction of the reagent hydrolysis product, the aqueous layer was injected directly onto a C18 reversed-phase column, and products were detected spectrofluorimetrically with excitation and emission wavelengths of 260 and 313 nm, respectively. Detection limits of 0.01 and 0.05 micrograms ml-1 were achieved for both 6-aminopenicillanic acid (6-APA) and isopenicillin N in borate buffer and filtered fermentation broths, respectively, using a 10-microliter injection volume. A linear calibration for 6-APA in fermentation broth was obtained for a very wide concentration range (0.05-100 micrograms ml-1). Detection limits for solutions of cephalosporin C, deacetylcephalosporin C and deacetoxycephalosporin C in broth were all 0.25 micrograms ml-1. The detection limit for the beta-lactam precursor delta-(L-aminoadipyl)-L-alpha-cysteinyl-D-valine (ACV) dimer in borate buffer was 0.5 microgram ml-1. The cephalosporins and ACV dimer gave linear plots in the ranges 3-25 and 1-100 micrograms ml-1, respectively. Repeated analysis of 6-APA at a concentration of 10 micrograms ml-1 in filtered broth gave a mean peak area of 2.5.10(6) with a standard deviation of 2.6.10(5) using a 10-microliter injection volume. Ampicillin spiked into deproteinated blood serum gave a linear calibration in the concentration range 2-100 micrograms ml-1.     

Column Preconcentration of Palladium Using Phenanthrenequinonedioxime Supported on Naphthalene by Atomic Absorption Spectroscopy

Abstract

A solid chelating compound, phenanthrenequinonedioxime(PQDO) supported on naphthalene provides a rapid and economical means of preconcentration of palladium from the aqueous samples. Palladium forms a complex with PQDO supported on naphthalene in the column at pH 1.2～2.7. The metal complex and naphthalene are dissolved out from the column with 5 ml of dimethylformamide-nitric acid (100+4) and the absorbance is measured atomic absorption spectrometer at 244.7 nm. A calibration curve is linear over the concentration range 1～24 μg of palladium in 5 ml of the final solution. The sensitivity for 1% absorption is 0.126 μg/ml (0.153 μg/ml for the direct AAS method from the aqueous medium). The method has been used for the determination of palladium in various synthetic samples and can be safely applied to the environmental samples too.     

Column preconcentration and FAAS determination of copper,iron, nickel and zinc using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol-tetraphenylborate-naphthalene adsorbent

A solid co-precipitated material obtained from an ion-pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) and tetraphenylborate (TPB), and microcrystals of naphthalene has been tried as an adsorbent for the column preconcentration of copper(I), iron(II), nickel(II) and Zn(II). The retention of the metal ions was found to be maximum and constant in the pH range 3.0-8.0 for Cu, 3.8-7.5 for Fe, 4.5-7.5 for Ni and 8.5-11.0 for Zn. The elements were determined by FAAS after dissolving the metal along with the adsorbent in an organic solvent (10 mL of DMF). The characteristic concentration for 1% absorption was found to be 0.0332, 0.0536, 0.0537 and 0.0142 (aqueous medium 0.0512, 0.0638, 0.1294 and 0.0216) microg mL(-1) for Cu, Fe, Ni and Zn, respectively. The calibration plot was linear in the range 1.5-20.0, 2.0-38.0, 2.5-25.0 and 0.5-15.0 micro g in the final 10 mL of DMF solution for Cu, Fe, Ni and Zn, respectively. Various parameters such as pH, volume of buffer, amount of adsorbent, flow rate, preconcentration factor and effect of diverse salts and cations were studied. The optimised conditions were utilized for the determination of Cu, Fe, Ni and Zn in various water, beverage and human hair samples.