Showing posts with label spectrophotometry. Show all posts
Showing posts with label spectrophotometry. Show all posts

Saturday, April 18, 2009

Baseline geochemical data for stream sediment and surface water

[PDF] Baseline analytical data for stream sediment and surface water ... - [ Terjemahkan laman ini ]
Jenis Berkas: PDF/Adobe Acrobat - Versi HTMLspectrophotometry following the method of O'Leary and Meier (1996). ... Co, Cr, Cu, Fe, Ga, Ge, La, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Pd, Pt, Sb, Sc, Sn, Sr, Th, Ti, V, W,. Y, Zn, and Zr. This method is designated ES in Table 2 and in the data ... This is particularly true for the major elements Al, Ca, Fe, K, Mg, ...

INTRODUCTION
During a 3-week period in the summer of 1996, the U.S. Geological Survey conducted a reconnaissance baseline geochemical study in central Idaho. Areas covered include Panther Creek, the Middle Fork of the Salmon River from Boundary Creek to the mouth, and the Main
Salmon River from North Fork to Corn Creek (Fig. 1). Stream sediment samples were collected
at all sample sites. Filtered and unfiltered stream water samples were collected at most sample
sites. The purpose of the baseline study was to establish a “geochemical snapshot” of the area,
as a datum for monitoring future change in the geochemical landscape, whether natural or human-induced. Events that could change the geochemical landscape include, but are not limited to, mining, flood, landslide, wildfire, or resource extraction activities. In the summer of 2000, there were numerous large wildfires in central Idaho. In particular, the Clear Creek (206,000 acres; 83,370 hectares), Little Pistol (74,000 acres; 29,950 hectares), and Shellrock (64,000 acres; 25,900 hectares) fires swept across much of the area that was sampled. Thus, these data represent a pre-fire baseline geochemical dataset. A 2001 post-fire study is planned and will involve re-sampling of the pre-fire baseline sites, to allow for pre- and post-fire comparison. Sampling was conducted from July 8-28, 1996. Weather during this period was warm and precipitation sparse. Only one rain event occurred during the sampling period—a brief rain storm on the evening of July 16, with about ¼” (0.64 cm) of total precipitation. River levels were lower than normal for this time of year because of lower-than-normal precipitation during
the previous winter and spring. The study area lies within the Salmon River Mountains, and much of the area— particularly along the Middle Fork of the Salmon River—lies within the Frank Church-River of No Return Wilderness (Fig. 1). Topographic relief is high. Peaks at the heads of drainages commonly have elevations above 9000 ft (2740 m), while river-level elevations are typically several thousand feet lower, ranging from around 5700 ft (1740 m) at Boundary Creek on the Middle Fork of the Salmon River, to less than 3000 ft (914 m) at Corn Creek on the Main
Salmon River. Terrain ranges from rugged, steep peaks, ridges, and cirques at higher elevations,
through tree-covered mountains and meadows at intermediate elevations, to steep, narrow, heavily vegetated canyons at lower elevations. Climatic conditions vary from warm summer days with frequent thunderstorms to cold winter days with heavy snowfall accumulations. Access to the Panther Creek basin is by U.S. Forest Service gravel roads 030 from North Fork, Idaho, and 055, which runs along Panther Creek. Access to the Main Salmon River from North Fork to Corn Creek is by U.S. Highway 93 and U.S. Forest Service gravel road 030, which runs along the Main Salmon, ending at Corn Creek, and by raft or jet boat. Access to the Middle Fork of the Salmon River is exclusively by oar-powered raft or pack trail.

OVERVIEW OF ENVIRONMENTAL ANALYSIS


A. INTRODUCTION
1. Environmental Analysis
Environmental analysis, as used in these notes, is the chemical (or physical) characterization of some component of the natural or engineered environment. One may speak of four facets to environmental analysis:
1. Analytical Methods
2. Sampling Protocol
3. Quality Control
4. Data Analysis
The first, analytical methods, is what one most commonly associates with chemical analysis of the environment. It is the recipe or set of laboratory procedures one follows in order to obtain a signal that can be related to the concentration of the analyte. Analytical methods are presented in Chapters XV-XXII, and grouped according to the instrument or apparatus used. The second facet, sampling protocol, is sometimes trivial, yet sometimes very important and complex. Sampling is the means by which a subset of the environmental matrix of interest is selected, stored and transported to the laboratory for analysis (Chapter XIII). Then, quality control, is a set of procedures which are intended to warn the analyst when his/her analytical method is not working properly (Chapter XII). Some of these procedures may be implicitly writted into the analytical method. Finally, data analysis, is required to place the analytical results into the framework of a numerical value with uncertainty. Statistical theory plays an important role in this process, and this subject is treated in Chapter XXIII.
2. Analytical Methods

Saturday, March 7, 2009

Organic Reagents in Spectrophotometric Analysis

Sergey B Savvin 1985 Russ. Chem. Rev. 54 1074-1090 doi: 10.1070/RC1985v054n11ABEH003158 Help


PDF (2.45 MB) | References

Abstract.

The spectrophotometric analytical methods using organic reagents in modern chemistry are discussed. Certain new organic reagents, synthesised in recent years, are presented. New methodological procedures in spectrophotometric analysis and the possibilities of the available apparatus are examined. The advances achieved in the development of the theoretical principles of the action of organic reagents are described and a new approach to the explanation of the reactivity of organic compounds is put forward.
The bibliography includes 200 references.

Thursday, March 5, 2009

Spectrophotometric

Beckman Instruments, Inc.: Bulletin 134-D. Fullerton, California. ...... been the basis for many published methods for the determination of ...... ments Ag, Al, B, Ba, Be, Or, Co, Cu, Fe, Mn,. Mo, Ni, Pb, Sn, Sr, Ti, V, Zn, and Zr are deter- ... Al, Ba, Mn, Ni, Cs, Sn,. Sr, Cr, Zn, Pb, Mo and Cd are monitored with ...

Study on color reaction of 2-(2-quinolylazo)-5-dimethylaminoanline with palladium and its application

Abstrasct
A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with QADMAA was developed. In the presence of 0.5-2.5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTMAB) medium, QADMAA reacts with palladium to form a violet complex of a molar ratio 1:2 (palladium to QADMAA). The molar absorptivity of the chelate is 1.35¡Á105 L.mol-1.cm-1 at 600 nm. Beer¡¯s law is obeyed in the range of 0.01~ 0.6 m g/ml. The relative standard deviation for eleven replicate sample of 0.2 m g/ml level is 1.02 %. This method had been applied to the determination of palladium with good results.
Keywords 2-(2-quinolylazo)-5-dimethylaminoaniline; palladium; spectrophotometry

Study on color reaction of 2-(2-quinolylazo)-5-dimethylaminoanline with palladium and its application

Abstrasct

A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with QADMAA was developed. In the presence of 0.5-2.5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTMAB) medium, QADMAA reacts with palladium to form a violet complex of a molar ratio 1:2 (palladium to QADMAA). The molar absorptivity of the chelate is 1.35¡Á105 L.mol-1.cm-1 at 600 nm. Beer¡¯s law is obeyed in the range of 0.01~ 0.6 m g/ml. The relative standard deviation for eleven replicate sample of 0.2 m g/ml level is 1.02 %. This method had been applied to the determination of palladium with good results.

Keywords 2-(2-quinolylazo)-5-dimethylaminoaniline; palladium; spectrophotometry



Supramolecular function of fluorescent probe/cyclodextrincomplex sensors in water

This paper reviewed the supramolecular function of fluorescent probe/cyclodextrin (CyD) complexes for ion and molecule recognition in water. Benzo-15-crown-5 fluoroionophores, Cn-15C5 (n=1, 3, 5), with different alkyl spacer lengths were first examined to develop supramolecular Cn-15C5/γ-CyD complex sensors for alkali metal-ion recognition in water. In organic solutions, C3-15C5 shows moderate Na+selectivity based on 1:1 complex formation. However, the C3-15C5/γ-CyD complex is found to selectively respond to K+ion in water and to exhibit pyrene dimer emission. An equilibrium analysis of the γ-CyD inclusion complexes in water reveals that the major component for the dimer emission is a 2:1:1 complex of C3-15C5 with K+and γ-CyD. Although the K+sensitivity of the C5-15C5/γ-CyD complex is comparable to that of the C3-15C5/γ-CyD complex, it also responds to Na+. The fluoroionophore C1-15C5, which has the shortest methylene spacer, exhibits no response to alkali metal cations in the presence of γ-CyD. Thus, the response function is strongly affected by the alkyl spacer length of Cn-15C5, and the highest K+selectivity in water is obtained for the C3-15C5/γ-CyD complex. The boronic acid fluoroionophore C4-PB/β-CyD complex binds sugars and produces increased fluorescence emission in water. A pH-fluorescence profile for the C4-PB/β-CyD complex reveals that the fluorescence intensity increases upon the formation of the boronate conjugate base. Upon the addition of fructose, the apparent pKa decreases to a lower pH, resulting in increased fluorescence at neutral pH. The fluorescence emission response of the C4-PB/β-CyD complex upon sugar binding appears to be due to suppression of the photoinduced electron transfer (PET) from the pyrene donor to the trigonal arylboronic acid acceptor.

SOIL GENESIS ON PERALKALINE FELSICS IN BIG BEND NATIONAL PARK, TEXAS


Abstract
Soil genesis involving felsic rocks frequently involves understanding the roles of climate and time on the transformations of the primary minerals into secondary products. This study focuses on the weathering of peralkaline felsics in a semiarid climate. Soils and fresh parent materials were collected from different microclimate regimes in the Chisos Mountains of Big Bend National Park, Texas. Soils in the Chisos mountains generally have either a mollic-argillic-rock or a mollic-rock horizon sequence, whereas other sites at lower and drier locations have an ochric-rock horizon sequence. Atmospheric deposition of Ca and Sr and wind deflation of clay are important attributes of soil genesis. Elemental loss rates of Si, Al, K, Na, and other elements are appreciable, suggesting that leaching has been important to the soil formation. Iron oxide formation, which is related to the moisture regime, is greater in soils having wetter microclimates. Solution chemistry suggests that Mg concentrations are appropriate for smectite synthesis and maintenance, potassium concentrations reflect the presence of feldspar, sodium concentrations reflect their loss rates because of leaching, and calcium reflects the presence of calcite. The rare earth elements similarly demonstrate loss rates consistent with chemical weathering. In general, chemical weathering of feldspars, atmospheric deposition of Ca and Sr, and wind deflation are important pedogenic processes.

Concentration Methods for the Determination of Trace Elements

Yurii A Zolotov 1980 Russ. Chem. Rev. 49 683-694 doi: 10.1070/RC1980v049n07ABEH002497

PDF (1.71 MB) References Articles citing this article
Yurii A Zolotov
Abstract. Methods of concentrating trace constituents are discussed, and the quantitative parameters used to describe them are defined. The main methods of concentration (extraction, sorption, coprecipitation, evaporation, etc.) are examined and compared. Rational combinations of methods of concentration and methods of determination of trace elements are recommended, and successful examples of such combinations are quoted. Special aspects of concentration methods applicable to the analysis of high-purity materials and of natural waters are discussed. 114 references.

Wednesday, March 4, 2009

Rapid Spectrophotometric Determination of Zirconium(IV)

Rapid Spectrophotometric Determination of Zirconium(IV) with 2,2,3,4-tetrahydroxy–3 -sulpho–5-chloroazobenzene in Alloys
A. Ali HÜSEYİNLİ,1†Fitnat KÖSEOĞLU,2 and Ülkü Dilek UYSAL1
1† Anadolu University, Faculty of Sciences, Department of Chemistry, 26470, Eskişehir, Turkey (E-mail: ahuseyin@anadolu.edu.tr)
2 Gazi University, Gazi Education Faculty, Teknikokullar, 06500, Ankara, Turkey
New o,o/–monoazo reagents have been synthesized using pyrogallol and 2-aminophenol-6-sulphonic acid or its derivatives. Spectrophotometric properties of the complexes formed by the reaction of synthesized monoazo reagents with Zr4+ have been investigated. According to the results it is found that the most sensitive and selective ligand for the Zr4+ is 2,2/,3,4-tetrahydroxy–3/-sulpho–5/-chloroazobenzene (tetrahydroxyazon SCl) and it was used for the direct spectrophotometric determination of Zr4+ion. Tetrahydroxyazon SCl reagent forms a red complex with Zr4+ ion in acidic media up to pH 6. The complex formation is fast and its absorbance reaches to a level immediately where remains constant for more than three days. The metal (M):ligand (L) ratio of the formed complex is 1:1 and the optimal wavelength of the
complex is 496 nm. Under optimum conditions Zr4+ ion acts in accordance with the Beer law at an ion concentration range of 0.08-3.20 μg/mL. The molar absorptivity was found as 34500 Lmol-1cm-1. The determination of Zr4+ was not interfered by Cu2+, Cd2+, Pb2+, Ni2+, Cr3+, Zn2+, Bi3+, U6+, Th4+, Al3+, Be2+, Co2+, Mn2+, Hg2+, halides, phosphates, sulfates, thiocyanides, urea, tartrate, ascorbic acid etc. This method is highly sensitive, selective, very rapid and a simple technique. It has been successfully applied to the determination of Zr4+ ion in an aluminum based certified alloys.

Monday, March 2, 2009

Extractive Spectrophotometric Determination of Tungsten(VI) Using 3-Hydroxy-2-(2'-Thienyl)-4-OXO-4H-1- Benzopyran

Abstract
A simple, rapid, highly sensitive and selective spectrophotometric method for the determination of tungsten(VI) in trace amounts is developed using 3- hydroxy-2-(2'-thienyl)-4-oxo-4H-1-benzopyran (HTB) as a reagent for the complexation of metal ion and extracting the 1:2 (metal:ligand) complex into dichloromethane from 0.2 M HCl solution. It obeys Beer's law in the range 0-2.8 g Wml-1 with molar absorptivity and Sandell's sensitivity at 415 nm as 6.45 x 104 L mol-1cm-1 and 0.0029 g W(VI) cm-2, respectively. The method is free from the interference of a large number (39) of elements and handles satisfactorily the analysis of various samples of varying complexity.


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Saturday, February 28, 2009

Study on Solid Phase Extraction and Spectrophotometric Determinationof Vanadium with 2-(2-Quinolylazo)-5-Diethylaminophenol


A sensitive, selective and rapid method has been developed for the determination μg/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with C18 cartridge. The QADEAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH = 3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1 : 2 (V(V) to QADEAP). This chelate was enriched by solid phase extraction with C18 cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is 1.28 × 105 L mol−1 cm−1 at 590 nm in the measured solution. Beer’s law is obeyed in the range of 0.01-0.6 μg/mL. The detection limit is 0.04 μg/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results.
Key Words : 2-(2-Quinolylazo)-5-diethylaminophenol, Vanadium, Spectrophotometry, Solid phase extraction

Tuesday, February 24, 2009

Membrane solubilization technique for spectrophotometric determination of trace formaldehyde in rainwater.

Anal Sci. 2008;24(11):1455-9.
Related Articles,
Links
Membrane solubilization technique for spectrophotometric determination of trace formaldehyde in rainwater.
Graduate School of Science and Engineering (Science Div.), University of Toyama, Toyama 930-8555, Japan.A simple and sensitive spectrophotometry for formaldehyde in water by membrane solubilization technique was proposed. Formaldehyde was converted into a blue cationic dye with 3-methyl-2-benzothiazolinone hydrazone, and the dye was retained on a membrane filter as an ion-associate with tetraphenylborate anion. The filter retaining the blue dye was dissolved in 2-methoxyethanol containing sulfuric acid, and the absorbance of the solution was measured at 670 nm against the reagent blank. The formaldehyde from 0.007 to 0.2 mg L(-1) was determined with an RSD of less than 5%, and the detection limit was 0.002 mg L(-1). The proposed method was very simple and rapid. Twenty minutes was sufficient for the entire analytical procedure. When the method was applied to rainwater, the analytical results were in good agreement with those obtained by GC/MS.
Publication Types:
Evaluation Studies
PMID: 18997375 [PubMed - indexed for MEDLINE]

Thursday, February 19, 2009

Spectrophotometric determination of tiopronin using its catalytic reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion.

Spectrophotometric determination of tiopronin using its catalytic reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion.
College of Chemistry and Environmental Science, Henan Normal University, The Key Laboratory of Environmental Pollution Control Technology of Henan Province, USA. mercury6068@hotmail.comA novel and simple spectrophotometric method for the determination of tiopronin with sodium 1,2-naphthoquinone-4-sulfonate (NQS) is established in this paper. The detailed mechanism is proposed and discussed. It is based on the fact that tiopronin can catalyze the reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in a buffer solution of pH 13.00 at the maximal absorption wavelength of 445 nm. When tetradecyl benzyl dimethyl ammonium chloride (Zeph) is added to the solution, the sensitivity of the reaction is improved. Beer's law is obeyed in a range of 0.39 - 15.67 microg mL(-1). The equation of linear regression is A = 0.11749 + 0.05914C (microg mL(-1)), with a linear correlation coefficient of 0.9973. The detection limit is 0.2 microg mL(-1), RSD is 0.88% and the recovery rate is in the range of 96.6 - 103.9%. Furthermore, the method has been validated and successfully applied to the determination of tiopronin in pharmaceutical samples.PMID: 19139579 [PubMed - indexed for MEDLINE]

Spectrophotometric determination of quinolone antibiotics by an association complex formation with aluminum(III) and erythrosin.

Spectrophotometric determination of quinolone antibiotics by an association complex formation with aluminum(III) and erythrosin.Yamaguchi T, Nakao M, Nakahara R, Nishioka Y, Ikeda C, Fujita Y.Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan.A simple and sensitive spectrophotometric method for the determination of quinolone antibiotics was established based on an association complex formation with aluminum(III) and erythrosin. In the determination of ofloxacin as a quinolone antibiotic, Beer's law is obeyed in the range of 0.1 - 3.2 microg ml(-1), with an effective molar absorptivity at 555 nm and the relative standard deviation being 1.2 x 10(5) L mol(-1) cm(-1) and 0.9% (n = 6). This method was successfully applied to the assay of quinolone antibiotics in pharmaceutical preparations.Publication Types:
Evaluation Studies
Research Support, Non-U.S. Gov'tPMID: 19139586 [PubMed - indexed for MEDLINE]

Monday, February 16, 2009

Solid phase extraction and spectrophotometric determination ofpalladium with 2-(2-quinolylazo)-5-diethylaminobenzoic acid


Abstract: Asensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with 2-(2-quinolylazo)-5-diethylaminobenzoic acid (QADEAB) and the solid phase extraction of the Pd(II) –QADEAB chelate with a reversed phase polymer-based C18 cartridge was developed. In the presence of 0.05 – 0. 5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTAB) medium, QADEAB reacts with palladium(II) to form a violet complex with a mole ratio 1:2 (palladium to QADEAB). The chelate was enriched by solid phase extraction with a reversed phase polymer-based C18 cartridge.
An enrichment factor of 200 was obtained by elution of the chelate form the cartridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43  105 L mol-1 cm-1 at 628 nm. Beer’s law was obeyed in the range of 0.01 – 1.2 g/mL. The relative standard deviation for eleven replicate samples at the 0.2 g/L level was 2.18 %. The attained detection limit amounted to 0.02 g/L in the original samples. This method was applied to the determination of palladium in environmental samples with good results.
Keywords: 2-(2-quinolylazo)-5-diethylaminobenzoic acid, palladium, spectrophotometry, solid phase extraction.

Highly Selective Derivative SpectrophotometricDetermination of Tin (II) in Alloy Samples in the Presenceof Cetylpyridinium Chloride


Abstract
A simple, selective and sensitive spectrophotometric method has been developed for thedetermination of tin(II) using a newly synthesised reagent diacetylmonoxime p-hydroxybenzoylhydrazone in cationic micellar medium. The molar absorptivity and Sandell’s sensitivity of the coloured species are 3.20×104 L mol-1 cm-1 and 3.6 ng cm-2 respectively. Beer’s law is obeyed between 0.25-2.76 μg mL-1 of Sn(II)) at 430 nm. The stoichiometry of the complex was found to be 1:2 (metal: ligand). A highly selective first order derivative spectrophotometric method for the determination of tin is also reported. The developed procedure has been successfully applied for the determination of tin in various alloy samples and synthetic mixtures of some low melting alloys.
Key words: tin, diacetylmonoxime p-hydroxybenzoylhydrazone, micellar medium, derivative spectrophotometry


Highly Selective Derivative SpectrophotometricDetermination of Tin (II) in Alloy Samples in the Presenceof Cetylpyridinium Chloride


Abstract
A simple, selective and sensitive spectrophotometric method has been developed for thedetermination of tin(II) using a newly synthesised reagent diacetylmonoxime p-hydroxybenzoylhydrazone in cationic micellar medium. The molar absorptivity and Sandell’s sensitivity of the coloured species are 3.20×104 L mol-1 cm-1 and 3.6 ng cm-2 respectively. Beer’s law is obeyed between 0.25-2.76 μg mL-1 of Sn(II)) at 430 nm. The stoichiometry of the complex was found to be 1:2 (metal: ligand). A highly selective first order derivative spectrophotometric method for the determination of tin is also reported. The developed procedure has been successfully applied for the determination of tin in various alloy samples and synthetic mixtures of some low melting alloys.
Key words: tin, diacetylmonoxime p-hydroxybenzoylhydrazone, micellar medium, derivative spectrophotometry

Solid Phase Extraction and Spectrophotometric Determination of Mercury in Tobacco andTobacco Additives with 5-(p-Aminobenzylidene)-Thiothiorhodanine

Abstract
A highly sensitive, selective and rapid method for the determination of mercury based on the rapid reaction of mercury(II) with 5-(p-aminobenzylidene)-thiorhodanine (ABTR) and the solid phase extraction of the colored chelate with C18 disks has been developed. At pH 3.5 and in the presence of emulsifier-OP medium, ABTR reacts with mercury(II) to form a red chelate of a 1:2
(mercury to ABTR) molar ratio. This chelate was enriched by solid phase extraction with C18 disks and the retained chelate eluted form the disks with dimethyl formamide (DMF). An enrichment factor of 50 was achieved. In the DMF medium, the molar absorptivity of the chelate is 1.21×105 L mol-1 cm-1 at 545 nm, and Beer’s law is obeyed in the 0.01~3 μg mL-1 range in the measured solution. The relative standard deviation for eleven sample replicate measurements at the 0.01 μg mL-1 level is 1.7%. This method was applied to the determination of mercury in tobacco and tobacco additives and good preconcentration was found between proposed and comparative methods results.
Keywords: mercury, solid phase extraction, spectrophotometry, 5-(p-aminobenzylidene)- thiothiorhodanine

Derivative Spectrophotometric Determination of Cobalt in Alloys

Abstract
Cobalt was 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 3.6 - 8.2 from large volumes of aqueous solutions of various alloys and biological samples. After filtration, a solid mass consisting of the cobalt complex and naphthalene was dissolved with 5 ml of dimethylformamide (DMF), and the metal was determined by third-derivative spectrophotometry. The cobalt complex could alternatively be quantitatively adsorbed on tetradecyldimethylbenzylammonium-naphthalene adsorbent packed in a column and determined similarly. The detection limit was 30 ppb (signal to noise ratio = 2) and the calibration curve was linear for 0.1 - 11 ppm in dimethylformamide solution with a correlation coefficient of 0.9996 by measuring the distance, d3A/d λ3, between λ1 (612 nm) and λ2 (579 nm). Eight replicated determinations of 2 ppm of cobalt in dimethylformamide solution gave a mean intensity (peak to peak signal between λ1 and λ2) of 0.436 with a relative standard deviation of ±0.91%. The sensitivity of the method was 0.215 (d3A/dnm3) ml/µg, which was found from the slope of the calibration curve. Various parameters, such as the effect of the pH, the volume of the aqueous phase and the interference of a number of metal ions on the determination of cobalt has been studied in detail to optimize the conditions for the determination cobalt in various alloys and biological samples.

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