Spectrophotometric Determination Of Micro Amounts Research Articles

Trace Determination of Thorium with 6-Chloro-3-hydroxy-2- (2′-furyl)-4H-chromen-4-one as an Analytical Reagent

A simple, rapid, highly sensitive and selective method for the spectrophotometric determination of micro amounts of thorium(IV) has been worked out using 6-chloro-3-hydroxy-2-(2′-furyl)-4H-chromen-4-one (CHFC) as a complexing agents in a acidified (CH3COOH, pH 3.5) medium. The yellow complex shows a maximum absorbance at 425-435 nm. The method obeys Beer′s law upto 3.5 μg Th cm-2. As many as 31 cations and 11 anions and/or complexing agents do not interfere. The method has good reproducibility and can be satis-factorily applied to the determination of thorium in samples corresponding to Australian monazite in composition.

Triphenyltetrazolium chloride as a new analytical reagent for molybdenum(VI): Application to plant analysis

Solvent extraction of molybdenum(VI) ion associate with triphenyltetrazolium chloride (TTC) has been studied. TTC was proposed as reagent for the spectrophotometric determination of micro amounts of molybdenum(VI) at λmax 250 nm. The optimum conditions for extraction of molybdenum(VI) as an ionassociation complex with TTC has been determined. Beer’s law is obeyed in the range of 0.5–10 μg/mL molybdenum(VI). The molar absorptivity of the ion-pair is 1 × 106 L/mol cm. The sensitivity of the method is 9.6 × 10−5 μg/cm2. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: distribution constant KD = 32.64, extraction constant Kex = 2.19 × 1010 association constant β = 6.71 × 108. The interferences of different cations, anions on molybdenum(VI) determination were also investigated. A sensitive and selective method for the determination of microquantities of molybdenum(VI) has been developed. The determination was carried out without preliminary separation of molybdenum. A novel procedure of molybdenum(VI) extraction and spectrophotometric determination in different plant samples was examined.

A highly sensitive spectrophotometric determination of micro amounts of vanadium(V) in environmental and alloy samples by using 3,4-dihydroxybenzaldehydeisonicotinoylhydrazone (3,4-DHBINH)

3, 4-Dihydroxybenzaldehydeisonicotinoylhydrazone was prepared, characterized with spectral analyses and used for developing a new method for the simple, sensitive and rapid spectrophotometric determination of vanadium(V) which gives maximum absorbance at wave length 360 nm. The metal ion gives a yellow colored complex with 3, 4-DHBINH in acetate buffer of pH 5.5 with 1:1 (metal:ligand) composition. The method obeys Beer's law in the range 0.5-5.3 microg mL(-1) of vanadium(V). The molar absorptivity and Sandell's sensitivity were found to be 1.29 x 10(4) L mol(-1) cm(-1) and 0.003949 microg cm(-2) respectively. The correlation co-efficient of the V(V)-3, 4-DHBINH complex was 0.992 which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) as 0.424% (n = 5), and its detection limit 0.01677 microg mL(-1) of vanadium(V). The instability constant of the method was calculated by Asmus' method as 4.1666 x 10(-3). The interfering effect of various cations and anions were also studied. The proposed method was successfully applied to the determination of vanadium(V) in environmental samples (water and soil) tobacco leaves and alloy samples. The validity of the method was tested by comparing the results with those obtained using an atomic absorption spectrophotometer.

Selective and sensitive extractive spectrophotometric determination of micro amounts of palladium(II) in spiked samples: using a new reagent N-ethyl-3-carbazolecarbaxaledehydethiosemicarbazone

N-Ethyl-3-cabazolecarboxaldehydethiosemicarbazone (ECCT) is proposed as a new, sensitive and selective complexing reagent for the separation and extractive spectrophotometric determination of palladium(II) at pH: 4.0 to form a yellowish orange colored 1:1 chelate complex, which is very well extracted in to n-butanol. The absorbance was measured at a maximum wavelength, 410 nm. This method obeys Beer's law in the concentration range 0.0-6.6 microg mL(-1) and the correlation coefficient of Pd(II)-ECCT complex is 0.998, which indicates an excellent linearity between the two variables with good molar absorptivity and Sandell's sensitivity, 1.647 x 10(4) l mol(-1)cm(-1), 6.49 x 10(-3) microg cm(-2), respectively. The instability constant of complex calculated from Edmond's method, 2.724 x 10(-5) was in good agreement with the value calculated from Asmus' method 2.624 x 10(-5), at room temperature. The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.839. Edmond's method was observed to be a more selective method in the presence of EDTA, oxalate and phosphate ions. The method was successfully applied for the determination of Pd(II) in water samples, synthetic mixtures and hydrogenation catalysts, employing an atomic absorption spectrometer for comparing these results.

Application of artificial neural networks in multivariable optimization of an on-line microwave FIA system for catalytic kinetic determination of iridium(III).

A new rapid, selective and sensitive on-line microwave flow injection-kinetic method was developed for spectrophotometric determination of micro amounts of Ir(III), based on its catalytic effect on the m-acetylchlorophosphonazo (CPA-mA) and KIO(4) reaction in NaOH media. An on-line microwave oven was employed to accelerate the reaction. The reaction was followed spectrophotometrically by measuring the decrease of the absorbance of CPA-mA at 580 nm. The effect of five variables for the determination of Ir(III) was optimized by means of a multilayer artificial neural network using extended delta-bar-delta (EDBD) algorithms. Under the optimum experimental conditions, Ir(III) could be determined in the range 0.060-0.60 micro gZZZ;mL(-1) with detection limit of 0.02 micro gZZZ;mL(-1) and the sampling frequency of 34 h(-1). The proposed method was applied to the determination of micro amounts of Ir(III) in refined ore and secondary alloy with the recoveries from 91.4% to 109%.

Spectrophotometric determination of cobalt, nickel, palladium, copper, ruthenium and molybdenum after extraction of their isoamyl xanthate complexes into molten naphthalene

A method has been developed for the spectrophotometric determination of microamounts of Co(II), Ni(II), Cu(II), Pd(II), Ru(III) and Mo(VI) after extraction of their isoamyl xanthate complexes into molten naphthalene. The method has been applied to the determination of these metal ions in various alloys and in environmental samples (fly ash).

A Highly Sensitive and Selective Spectrophotometric Determination of Vanadium(V) Using 6-Chloro-3-hydroxy-7-methyl-2-(2-thienyl)-4H-chromen-4-one.

A simple, rapid, highly sensitive and selective method for the extractive spectrophotometric determination of micro amounts of vanadium(V) has been worked out using 6-chloro-3-hydroxy-7-methyl-2-(2-thienyl)-4H-chromen-4-one (CHMTC) as a complexing agent in a weakly acidified (HCl, pH 0.84–1.09) medium. The greenish-yellow complex is quantitatively extractable into carbon tetrachloride, and shows maximum absorbance at 417–425 nm. The method obeys Beer’s law up to 0.9 m g V ml–1, having molar absorptivity and Sandell’s sensitivity of 8.26×104 dm3 mol–1 cm–1 and 0.0006 m g V cm–2, respectively. As many as 39 cations and 14 anions and/or complexing agents do not interfere. The method has good reproducibility and can be satisfactorily applied to the determination of vanadium in steels, reverberato-ry flue dust and water samples.

Study on the spectrophotometric determination of micro amounts of selenium(IV) with 2,3-diaminonaphthalene in the presence of sodium dodecylsulphate

A method for the spectrophotometric determination of micro amounts of selenium(IV) in aqueous phase has been developed. A time-consuming extraction process is not required due to the use of sodium dodecylsulphate (SDS). Over the range of 0–40 μg/10 ml the calibration curve is linear with Sandell's sensitivity being 0.0029 μg.cm–2. As compared with the toluene-extraction spectrophotometry, the present method is simple, rapid and sensitive. It has satisfactorily been used for the determination of Se(IV) in human hair.

Spectrophotometric Determination of Trace Amounts of Palladium with Molybdate and Rhodamine B in the Presence of PVA

Abstract A new spectrophotometric method for the determination of palladium has been developed, based on the reaction of palladium (II) with molybdate and rhodamine B(RB) to form an ion-association complex in the presence of poly (vinyl alcohol). The molar absorptivity at 585 nm is 4. 06 × 105 1 mol−1 cm−1. Beer's law is obeyed over the range 0∼4 μg of palladium per 25 ml. The molar ratio of Pd to RB in the complex is established to be 1:4. Over 30 foreign ions were tested. The method can be applied to the spectrophotometric determination of microamounts of palladium in samples of aluminium based and active carbon catalysts.

Spectrophotometric determination of microamounts of yttrium with 1-amino-4-hydroxyanthraquinone

1-amino-4-hydroxyanthraquinone (AMHA) is proposed as a spectrophotometric reagent for the determination of yttrium. The solution equilibria ofAMHA complexes with Y(III) have been studied spectrophotometrically in 50% (v/v) ethanol at 25°C and an ionic strength ofI=0.1 mol·dm−3 (NaClO4). The complexation reactions were investigated and characterized using graphical logarithmic analysis of the absorbance graphs. The composition, molar absorptivities, and stability constants of the chelates ofAMHA with Y(III) have been determined spectrophotometrically. A simple, rapid, selective, and sensitive method for the spectrophotometric determination of microamounts of Y(III) is developed based on the formation of the violet YLH+ complex with λmax=580nm atpH 6.2(e=0.98×104l·mol−1·cm−1). Interferences and their elimination have been studied. Many foreign ions are tolerated in considerable amounts; 45–60 fold amounts of rare earths do not interfere with the determination of yttrium. In the determination of yttrium in synthetic polymetallic samples the relative error and relative standard deviation of the method were found to be better than 1 and 0.5%, respectively.

Spectrophotometric determination of microamounts of thorium with disodium salt of 2-(2-hydroxy-3,6-disulfo-1-naphthylazo)-benzenearsonic acid (Thorin) as a chromogenic reagent

A sensitive spectrophotometric method has been developed for the determination of microamounts of thorium using 0.05% thorin in a 3M perchloric acid solution as a chromogenic reagent and measuring the absorbance at 544 nm. The complex of thorium thus formed, is stable for more than two months with a constant absorbance of ±0.55%. Beer's law is obeyed from 0 to 25 μg g−1 of thorium in a solution with a molar absorptivity (ɛ544 nm) = 1.69×104 M−1 cm−1 at 26±1 °C. Among the anions tested, only phosphate, acetate and cyanide at >200-fold excess of thorium interfere in the determination, whereas cations like Zn(II), Al(III), Na(I), Mg(II), and Ca(II) do not effect the absorbance. Thorium can be determined in the presence of oxalate, nitrate, tartrate, sulfate, thiosulfate, citrate, and ascorbate. The accuracy of the method has been checked by measuring the known concentration of thorium in the range of 100 μg-5 mg g−1 and found to be in the range of 7.7–0.9%. The method has been applied successfully to determine thorium at μg g−1 level in local ore samples with a precision of ±0.3%. The sensitivity of the method on Sandell's scale is 0.082±0.002 μg g−1 cm−1.

Flow-Injection Spectrophotometric Determination of Micro Amounts of Sulfate Ion in Surface- and Sea-Water Samples with a Barium Chromate Reaction Column

A rapid and simple flow-injection method using a reaction column packed with barium chromate powder is described for the determination of micro amounts of sulfate ion in surface- and sea-water samples. An aqueous solution containing 4.5mM sodium acetate and 4% ethanol was used as a carrier solution at a flow rate of 0.8ml/min. The absorbance of the chromate ion (which corresponds to the sulfate ion concentration) in the carrier solution from the reaction column was measured using a photometric detector at 370nm. Interference from some cations was eliminated by the use of a cation-exchange resin column installed in front of the reaction column; interference from some anions was reduced by using the carrier solution mentioned above. The concentration range from 0.5 to 5ppm of the sulfate ion in practical water samples can be determined by the proposed method with good reproducibility.

Sensitive spectrophotometric determination of micro amounts of d-penicillamine using an indirect redox technique

A spectrophotometric method for the determination of micro amounts of d-penicillamine (PNCL) is described, based on the oxidation of the PNCL by Fe(III) in the presence of o-phenanthroline, with which the Fe(II) resulted forms a ferroin complex. The latter exhibits an absorption maximum at 510 nm with an apparent molar absorptivity of 1.01 × 10 4 l mol −1 cm −1 and a Sandell sensitivity of 14.7 ng cm −2 (for log I 0/ I = 10 −3), both referred to the drug analysed. The optimum concentration range is 2.0–15.0 μg ml −1 of PNCL. The regression equation is A = 7.46 × 10 −2 C-3.70 × 10 −2 with a correlation coefficient of 0.9997 ( n = 28). Statistical analysis indicated that there was no significant difference between the results obtained by the described method and those of the official USP XXII method.

Spectrophotometric determination of micro amounts of beryllium in waste water with chromeazurol S (CAS) and cetylpyridinium chloride (CPC) after separation by dynamic adsorption on activated carbon

A spectrophotometric method for the determination of microamounts of beryllium in waste water has been developed using CAS and CPC. The interference of foreign ions can be eliminated by separation with dynamic adsorption on activated carbon. Beer's law is obeyed for 0 to 0.7 μg of Be in 25 ml of solution. The apparent molar absorptivity is 7.9×104 l mol−1 cm−1 at 605 nm. The method has been used to determine beryllium in several industrial waste waters.

Spectrophotometric determination of micro amounts of tetrathionate via its oxidation with permanganate

The reaction conditions of tetrathionate with permanganate were investigated by varying reaction time, temperature and amounts of sulphuric acid and permanganate. Under the optimal conditions for the reaction of tetrathionate with permanganate, both penta- and hexathionate were also oxidised; each one mol of polythionates (S x O 6 2− ∶x=4, 5 and 6) reacts with (x−1.5) mol of permanganate. The proposed method is based on the reaction of tetrathionate with a given excess amount of permanganate in a sulphuric acid medium and on the spectrophotometric measurement of the iodine as triiodide formed by the oxidation of iodide with the excess of permanganate. This method could be successfully applied to the determinations of tetrathionate (4 × 10−7 to 2 × 10−5 M), pentathionate (3 × 10−7 to 1.43 × 10−5 M) and hexathionate (2 × 10−7 to 1.11 × 10−5 M), and gave a higher sensitivity than any previous methods without solvent extraction.

Extractive Spectrophotometric Determination of Micro Amounts of Palladium with N,N′-Diphenylpropanedithioamide (DPDTA) and Equilibria and Kinetics of Extraction of Palladium with DPDTA

N, N′-Diphenylpropanedithioamide (DPDTA) forms a stable 1:2 (metal:ligand) complex with palladium(II), which is quantitatively extracted from aqueous solutions of pH 1.5-5.8 into toluene, the extract having an absorption maximum at 357nm. Beer′s law is obeyed over the range 0.1-2.0μg ml-1 of palladium. The apparent molar absorptivity is 4.76×104M-1 cm-1. A sensitive and selective extraction-spectrophotometric method for the determination of micro amounts of palladium has been proposed. Further, the equilibria and kinetics of the extraction of palladium(II) with toluene solutions of DPDTA have been studied. The partition coefficient of DPDTA and the extraction constant of its palladium(II) complex between an aqueous and a toluene phase were determined to be 103, 13 and 107.56, respectively. The reaction orders of the rate of the complexation reaction of palladium(II) with DPDTA in the extraction were +1, 0 and +1 with respect to the concentrations of palladium(II), hydrogen ion and DPDTA, respectively. Kinetic data and activation parameters for the reaction have also been determined.

Indirect spectrophotometric determination of micro-amounts of tin(II) in the presence of tin(IV) and in dental gels

A method for determining microgram amounts of tin(II) in synthetic samples containing tin(IV) and in dental gels has been developed. The procedure involves the oxidation of tin(II) with iron(III) in hydrochloric acid and spectrophotometric determination of the resulting iron(II) as a FerroZine complex.

Spectrophotometric Determination of Micro Amounts of Sulfide, Sulfite and Thiosulfate

The present method is based on the spectrophotometric measurement of an excess amount of iodine for the reaction of iodine with sulfide, sulfite and thiosulfate in a mixture after proper chemical treatments; it consists of three Procedures: I, II and III. The absorbance obtained by Procedure I corresponds to the sum of the thiosulfate and twice the sulfide and sulfite in the mixture. The absorbance obtained by Procedure II, where sulfite was masked by formaldehyde, corresponds to the sum of the thiosulfate and twice the sulfide. The absorbance obtained by Procedure III corresponds to only the amount of thiosulfate, because sulfite was masked by formaldehyde and sulfide was eliminated with the suspension of zinc carbonate hydroxide. The conditions under which all the three sulfur species in a mixture can be stable and react stoichiometrically with iodine were established. The method is applicable to the determination of sulfur species in amounts more than 0.05μmol and gave a relative standard deviation of 3% at 0.4μmol level. It has been applied to the determination of sulfide, sulfite and thiosulfate in various amounts in several fumarolic condensate samples.

Spectrophotometric determination of micro amounts of hexathionate via permanganate reaction.

Spectrophotometric determination of micro amounts of hexathionate via permanganate reaction.

Enzyme method for the spectrophotometric determination of micro-amounts of cyanide.

An enzyme method is described for the determination of micro-amounts of cyanide in aqueous and serum samples. The method was based on measurement of the absorbance at 460 nm of the iron(III) thiocyanate complex formed from thiocyanate produced in the enzyme-catalysed reaction. The enzyme rhodanese (E.C. 2.8.1.1) catalysed the reaction between the cyanide ion and thiosulphate with stoicheiometric formation of thiocyanate. Only a small concentration of enzyme was required. Linear calibration graphs were obtained in the range 0–20 mg l–1 of cyanide in both aqueous and serum samples, with a detection limit of 0.1 mg l–1. The precision of the method is better than 2.5% relative standard deviation at 5 mg l–1 of cyanide. Because there was almost no incubation period required for the enzyme reaction, the method is very rapid and has potential for automation for the routine analysis of environmental and clinical samples. Ten-fold concentrations of acetate, ascorbate, citrate and iodide were found to interfere with the determination of cyanide concentrations <1 mg l–1.