4-(N,N-diethylamino) benzaldehyde thiosemicarbazone in the spectrophotometric determination of palladium

4-(N,N-diethylamino)benzaldehyde thiosemicarbazone(DEABT) is proposed as a sensitive and selective analytical reagent for the spectrophotometric determination of palladium(II). The reagent reacts with palladium (II) in a potassium hydrogen phthalate-hydrochloric acid buffer of pH 3.0, to form a yellow complex. Beer's law is obeyed in the concentration range up to 3.60 microgmL(-1). The optimum concentration range for minimum photometric error as determined by Ringbom plot method is 0.36 - 3.24 microg mL(-1). The yellow Pd(II)-DEABT complex shows a maximum absorbance at 408 nm, with molar absorptivity of 3.33 x 10(4) dm3 mol(-1) cm(-1) and Sandell's sensitivity of the complex from Beer's data, for D = 0.001, is 0.0032 microg cm(-2). The composition of the Pd(II)-DEABT complex is found to be 1:2 (M:L). The interference of various cations and anions in the method were studied. The proposed method was successfully used for the determination of Pd(II) in alloys, catalysts, complexes and model mixtures with a fair degree of accuracy.     

Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

Determination of nickel with 2-(2-quinolylazo)-5-diethylaminoaniline as a chromogenic reagent.

A sensitive, selective and rapid method for the determination of nickel based on a rapid reaction of nickel(II) with 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) has been developed. In the presence of pH = 6.0 ammonia-ammonium chloride buffer solution and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with nickel to form a violet complex having a molar ratio of 1:2 (nickel to QADEAA). The molar absorptivity of the complex is 1.38 x 10(5) l mol(-1) cm(-1) at 595 nm. Beer's law is obeyed in the range of 0.01-0.4 microg/ml. This method had been applied to the determination of nickel with good results.     

Selective determination of cobalt using polyurethane foam and 2-(2-benzothiazolylazo)-2-p-cresol as a spectrophotometric reagent

The present work describes a selective, rapid and economical method for the determination of cobalt using the 2-(2-benzothiazolylazo)-p-cresol (BTAC) as a spectrophotometric reagent associated with a solid extraction on polyurethane foam. The BTAC reacts with Co(II) in the presence of Triton-X100 surfactant forming a green complex with maximum absorption at 615 nm. The reaction is used for cobalt determination within a pH range of 6.50-7.50, with an apparent molar absorptivity of 1.62 x 10(4) L mol(-1) cm(-1). Beer's Law is obeyed for a concentration of at least 1.60 microg ml(-1). A selective procedure is proposed for cobalt determination in the presence of Fe(II), Hg(II), Zn(II) and Cu(II) up to milligram levels using masking agents. Polyurethane foam is used for the preconcentration and separation of cobalt from thiocyanate media and this procedure is applied to its determination in nickel salts and steel alloys.     

Spectrophotometric determination of nickel with p-acetylarsenazo

A spectrophotometric method for the determination of trace amounts of nickel is described. At pH 6, nickel reacts with p-acetylarsenazo to form a 1:2 coloured complex with an absorption maximum at 630 nm. The apparent molar absorptivity is 6.5 x 10(4) l.mol(-1) . cm(-1) . Beer's law is obeyed over the concentration range of 0-0.8 microg/ml. The proposed method is selective, sensitive and can be applied to the determination of nickel in aluminum alloy.     

o-Amino heterocyclic azo-dyes as analytical reagents-II Spectrophotometric determination of cobalt with 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine

Cobalt(II) and 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine (5-Cl-PADAPy) in slightly acid, neutral or alkaline media form a blue complex which is very stable even in the presence of mineral acids. The complex has two absorption maxima, at 575 and 620 nm. in 1.2M hydrochlororic acid. The system conforms to Beer's law; the optimal range for a 1-cm cell is 0.2-1.2 ppm cobalt. Milligram amounts of common anions and cations do not interfere. The molar absorptivity is 3.69 x 10(4) 1.mole(-1).cm(-1) at 620 nm.     

Study of 2-(2-quinolinylazo)-5-dimethylaminobenzoic acid as a new chromogenic reagent for the spectrophotometric determination of cobalt

2-(2-Quinolinylazo)-5-dimethylaminobenzoic acid (QADMAB) is proposed as a new sensitive and selective chromogenic reagent for spectrophotometric determination of cobalt. The QADMAB reacts with cobalt in the presence of cetyl trimethylammonium bromide (CTMAB) medium to form a violet complex of molar ratio 1:2 (cobalt to QADMAB) in the pH range 3.2-5.2. The molar absorptivity of the complex is 1.28x10(5) L mol(-1) cm(-1) at 625 nm. Beer's law is obeyed in range 0.01-0.32 micro g mL(-1). The relative standard deviation for eleven replicate samples of 0.2 micro g mL(-1) is 0.76%. This method was applied to the determination of cobalt in biological samples, Vitamin B(12), alloys and water with good results.     

Diformylhydrazine as analytical reagent for spectrophotometric determination of iron(II) and iron(III)

The bidentate ligand diformylhydrazine (OHC-HN-NH-CHO), DFH, combines with iron(II) and iron(III) in alkaline media in the pH range 7.3-9.3 to form an intensely colored red-purple iron(III) complex with an absorption maximum at 470 nm. Beer's law is obeyed for iron concentrations from 0.25 to 13 microg mL(-1). The molar absorptivity was in the range 0.3258x10(4)-0.3351x10(4) L mol(-1) cm(-1) and Sandell's sensitivity was found to be 0.0168 microg cm(-2). The method has been applied to the determination of iron in industrial waste, ground water, and pharmaceutical samples.     

Rapid and selective spectrophotometric determination of manganese in steels and alloys using resacetophenone oxime

A sensitive spectrophotometric method is developed for the determination of manganese in aqueous medium. The metal ion forms a yellowish brown coloured complex with resacetophenone oxime (RPO) in ammonium chloride and ammonium hydroxide buffer of pH 10.5. The 1:1 complex shows maximum absorbance at 380 nm with a Beer's law range of 0.09-1.7 ppm. The molar absorptivity and the Sandell sensitivity are found as 2.5 x 10(4) l.mole(-1).cm(-1) and 0.002 mug/cm(2), respectively. The stability constant of the complex calculated by Job's method is 7.5 x 10(5). The interfering effects of various cations and anions are studied. The present method is applied to the determination of manganese in some steel and alloy samples.     

Highly sensitive extractive spectrophotometric determination of palladium(II) in synthetic mixtures and hydrogenation catalysts using benzildithiosemicarbazone.

A simple and highly sensitive method was developed for the extractive-spectrophotometric determination of palladium with benzilidithiosemicarbazone. The metal ion formed a reddish brown complex with benzildithiosemicarbazone in a potassium chloride-hydrochloric acid buffer of pH 2.5, which was easily extractable into methyl isobutyl ketone. The 1:1 complex showed the maximum absorbance at 395 nm with a Beer's law range of 0.25-3.5 ppm. The molar absorptivity and Sandell's sensitivity were found to be 3.018 x 10(4) dm3 mol(-1) cm(-1) and 0.0035 microg cm(-2), respectively. The correlation coefficient of the Pd(II)-BDTSC complex was 0.998, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) (n = 10), which was 0.46%. The instability constant of the complex calculated from Edmond and Birnbaum's method was 2.41 x 10(-5), that of Asmus' method is 2.53 x 10(-5) at room temperature. The interfering effects of various cations and anions were studied. The proposed method was successfully applied to the determination of palladium(II) in synthetic mixtures and hydrogenation catalysts. The validity of the method was tested by comparing the results with those obtained using an atomic absorption spectrophotometer.     

Extractive-spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone

The optimum conditions for the extractive-spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone have been established. Iron(II) reacts with this reagent at pH 2.0-7.5 to form an uncharged 1:2 (metal-to-ligand) complex, which can be extracted with toluene. Beer's law is obeyed over the range up to 0.84 mug/ml of iron(II) at 505 nm. The molar absorptivity of the extracted species is 5.83 x 10(4) 1.mole(-1).cm(-1). The proposed method is extremely sensitive and reproducible, and has been satisfactorily applied to the determination of total iron in freshwater samples by adding ascorbic acid to reduce iron(III).     

Rapid spectrophotometric determination of ruthenium with diethazine hydrochloride

Diethazine hydrochloride reacts with ruthenium(III) instantaneously at high acidity (sulphuric or hydrochloric acid) to form a red 1:1 complex with absorbance maximum at 515nm. A tenfold molar excess of reagent is necessary for complete complexation. Beer's law is obeyed for 1.0-10.4 ppm of ruthenium(III), with optimum concentration range 2-9 ppm. The molar absorptivity is 5.35 x 10(3) 1.mol(-1) .cm(-1).     

6-Chloro-3-hydroxy-2-(5'-methylfuryl)-4H-chromene-4-one as an analytical reagent for micro determination of molybdenum(VI).

6-Chloro-3-hydroxy-2-(5'-methylfuryl)-4H-chromene-4-one (CHMFC) has been used as an analytical reagent for the spectrophotometric determination of molybdenum. Molybdenum(VI) in the presence of several cations, anions and complexing agents forms a yellow 1:2 complex with CHMFC. The complex is quantitatively extractable into 1,2-dichloroethane from 1 mol dm(-3) acetic acid medium and is stable for more than 6 h. The complex shows an absorption maximum at 438 nm with a molar absorptivity of 5.36 x 10(4) dm3 mol(-1) cm(-1) and Sandell's sensitivity equal to 0.0017 microg Mo cm(-2). The method obeys Beer's law up to 1.9 microg Mo ml(-1). The relative standard deviations are 0.2% for solutions and 0.5-1.5% for solid samples. The method is simple, selective, precise and rapid, and has been satisfactorily applied to the micro determination of molybdenum in various synthetic and standard samples.     

Extractive spectrophotometric determination of trace amounts of iron(III) with benzyltriethylammonium chloride

The ion-association complex formed between a thiocyanato-iron(III) ion and a benzyltriethylammonium ion is extracted into 1,2-dichloroethane, and its absorbance at 476 nm is used for determination of the iron. Beer's law is obeyed up to about 4 mug/ml iron concentration in the final solution. The molar absorptivity is 2.79 x 10(4) l.mole(-1).cm(-1).     

Capillary electrophoresis and circular dichroism study of trichosanthin and its mutants

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver (I) with QADEAA has been developed. In the presence of sodium citrate-sodium hydroxide buffer solution (pH 6.5) and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with silver to form a violet complex of molar ratio 1:2 (silver to QADEAA). The molar absorptivity of the complex is 1.39x10(5) l mol(-1) cm(-1) at 580 nm. Beer's law is obeyed in the range of 0.01-0.6 mug ml(-1). The relative standard deviation for 11 replicate samples of 0.2 mug ml(-1) is 1.67%. This method can be applied to the determination of silver in water with satisfactory results.     

Spectrophotometric determination of gallium(III) with phenylfluorone in the presence of hexadecylpyridinium bromide and pyridine

Phenylfluorone reacts with gallium in the presence of hexadecylpyridinium bromide and pyridine to form a water-soluble chelate with an absorption maximum at 570 nm and constant absorbance in the pH range 4.0-5.5. At this wavelength, Beer's law is obeyed up to 4.3 x 10(-6)M gallium. The sensitivity is very high and the molar absorptivity is 1.48 x 10(5) 1.mole(-1).cm(-1). The chelate has been utilized in the determination of gallium at the mug level. The ratio of gallium to phenylfluorone in the complex is 1:2.     

Spectrophotometric determination of samarium(III) with chrome azurol S in the presence of cetylpyridinium chloride

A sensitive, simple method for the determination of trace amounts of samarium by spectrophotometry is described based on the formation of the samarium-chrome azurol S (CAS) complex in micellar medium. The molar absorptivities of the complexes at pH 7.5 at 505 nm were 3.6x10(4) and 1.4x10(5) l mol(-1) cm(-1) for water media and cetylpyridinium chloride (CPC), respectively. Beer's law is obeyed from 0.05-2 mg l(-1) of samarium at 505 nm as Sm-CAS-CPC complex. Optimal conditions such as reagent amounts, and pH for the samarium determination were reported. The effects of foreign ions were also investigated. The proposed method was successfully applied to the determination of samarium contents in synthetic samples.     

Spectrophotometric determination of paracetamol with microwave assisted alkaline hydrolysis

A novel and rapid spectrophotometric method for the determination of paracetamol is proposed in this paper. The proposed method is based on the microwave assisted alkaline hydrolysis of paracetamol to p-aminophenol that reacts with S2- in the presence of Fe3+ as oxidant to produce a methylene blue-like dye having an absorptivity maximum at 540 nm. The experiment showed that paracetamol could be hydrolysed quantitatively to p-aminophenol in only 1.5 min under radiation power 640 W using a microwave in NaOH medium. The system obeys Beer's law in the range of 0-3.0 x 10(-4) mol l(-1) paracetamol. The molar absorptivity and Sandell's sensitivity were found to be 3.2 x 10(-3) l mol(-1) cm(-1) and 0.047 microg cm(-2), respectively. The relative standard deviation (n=11) was 1.7% for 8.0 x 10(-5) mol l(-1) paracetamol. The method has been applied successfully to analysis of paracetamol in pharmaceutical preparation.     

Colour reaction of platinum(II) with 5-(4-nitrophenylazo)-8-(p-toluenesulphonamido)-quinoline and its analytical applications

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of platinum. 5-(4-Nitrophenylazo)-8-(p-toluenesulphonamido)quinoline (NPTSQ) reacts with platinum(II) almost instantaneously in alkaline solution to form a violet-red 1:2 complex with an absorption maximum at 640 nm. Beer's law is obeyed over the concentration range 0-1 mug/ml platinum. The molar absorptivity is 1.37 x 10(5) 1.mole(-1).cm(-1). The method has been used for the determination of microamounts of platinum in catalysts and anode slime.     

Spectrophotometric determination of trace copper in water samples with thiomichlersketone

A simple and sensitive spectrophotometric method for determination of trace copper in water samples is proposed. In the presence of pH 4.6 HAc-NaAc buffer solution and surfactant polyethylene octyl phenyl ether (OP) medium, copper reacts with thiomichlersketone (TMK) to form a stable 1:4 complex. The complex Cu(II)-TMK-OP shows maximum absorbance at 500 nm with a molar absorptivity value of 5.7x10(4) l mol-1 cm-1. Beer's law is obeyed for copper concentrations in the range of 0-15 microg/25 ml. The average recovery of copper is between 95.8 and 106%. The method has been applied for determination of trace copper in different water samples with satisfactory results.