Extraction-spectrophotometric determination of traces of palladium by reaction between zinc(II) dibenzyldithiocarbamate and palladium(II)/2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

The simple and highly sensitive determination of palladium is based on the reaction between Pd(II)/5-Br-PADAP and Zn(II) DBDTC complexes in 1,2-dichloroethane or toluene at pH 9.7. At 530 nm, the molar absorptivity is about 0.8 × 10⁵ l mol ^?1 cm ^?1. Beer's law is obeyed in the concentration range 0.1–1.2 μg ml ^?1 Pd. Relative standard deviations are 2–5%. Metal ions reacting with either of the organic reagents interfere.     

Spectrophotometric determination of cadmium(II) using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

The complex of cadmium with the reagent 2-(-5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) has been studied. The composition, stability constant, and free energy change of formation of the complex have been determined. A sensitive spectrophotometric method for the determination of cadmium has been developed and applied for a range of concentration of 0.4–4.0 μg/ml cadmium using the complex Cd-5-Br-PADAP. The optimum conditions for maximum sensitivity of determination such as standing time, pH, wavelength, and order of addition have been determined. The effect of foreign ions on this method has been also studied.     

Sensitive spectrophotometric determination of nickel(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

A simple, selective and highly sensitive procedure for spectrophotometric determination of nickel has been developed. At pH 5.5, nickel reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in water-ethanol medium to form a red-violet complex which has two absorption maxima, at 520 and 56Onm. The molar absorptivity at 56Onm is 1.26 x 10(5) l.mole(-1).cm(-1). Beer's law is obeyed for 0-15 mug of nickel. Nickel in aluminium alloys and electroplating waste-water has been determined by this method.     

A study of the spectrophotometric determination of traces of cadmium(II) and copper(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of polyglycol octylphenyl ether

A spectrophotometric study of the Cd(II) and Cu(II) complex of a new reagent, 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol (5-Br-PADAP) in the presence of polyglycol octylphenyl ether (OP) is presented. A reddish binary complex is formed at pH 9 and shows maximal absorbance at 560 nm with molar absorptivity of 1.16 × 10⁵ · mol⁻¹ · cm⁻¹ liter (Cd), 1.5 × 10⁵ mol⁻¹ · cm⁻¹ · liter (Cu). Beer's law is followed over the range 0.0 to 20 μg cadmium(II) and 0.0–18 μg copper(II). The continuous variation method and molar ratio method showed that the metal ligand ratio is 1:2; ordinarily, most ions do not interfere with the determination and the method can be applied for direct spectrophotometric determination of cadmium(II) and copper(II) in actual samples and the results obtained are satisfactory.     

Adsorption voltammetry of the copper(II) 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex

The voltammetric determination of copper(II), based on adsorptive accumulation of the Cu(II)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (S-Br-PADAP) complex on a hanging mercury drop electrode, is reported. The complex can be accumulated at the electrode at constant potential in 0.1M ammonium nitrate/ammonia buffer solution, and its reduction wave observed by scanning the potential in the negative direction, in the differential pulse mode. The calibration graph for copper is linear over the range 0.05-0.5muM, with accumulation for 5 min at -0.20 V. The adsorption of the complex is discussed and compared with that of copper complexes with several other pyridylazo derivatives.     

Rapid spectrophotometric determination of zirconium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

Zirconium reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the pH range 3.8-5.8 to form a red chelate that is soluble in methanol-water mixtures. The absorbance of the 1:3 complex obeys Beer's law over the zirconium concentration range 0.02-0.44 mug/ml and has a molar absorptivity of 1.54 x 10(5) 1.mole(-1). cm(-1) at 585 nm. The formation constant is log beta(3) = 16.15. Of 59 species studied, only EDTA, Ga, In, Ti, Hf and V(V) interfere seriously.     

Simultaneous derivative spectrophotometric determination of zinc and cadmium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride.

A selective and sensitive derivative photometric method has been developed for the determination of trace amounts of Zn2+ with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant. The molar-absorption coefficient and analytical sensitivity of the 1:2 complex at 554 nm are 1.19 x 10(5) L mol(-1) cm(-1) and 0.56 ng mL(-1), respectively. The detection limit is 1.96 x 10(-2) ng mL(-1) and Beer's law is valid in the 0.02-0.66 microg mL(-1) range of Zn2+. The developed derivative procedure, using the zero-crossing measurement approach, is applied for the rapid and selective simultaneous determination of Zn2+ and Cd2+ in the range of 0.06-0.66 and 0.20-1.60 microg mL(-1), respectively. Complex matrices, including reference materials, environmental and biological samples and synthetic mixtures, have been successfully analyzed for trace amounts of the two metal ions.     

Sensitive spectrophotometric determination of bismuth(III) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

The complex of the reagent 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) with Bi(III) has been studied. The composition and stability of this complex have been determined. An analytical method for the spectrophotometric determination of Bi(III) using its complex with 5-Br-PADAP has been developed. Variables influencing the method such as pH, wavelength, and time have been studied. The limitations of this method and the effect of interfering ions have been investigated. Comparison of this method with other methods cited in the literature for the determination of Bi(III) is also included.     

Spectrophotometric determination of gadolinium(III) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)

Reaction between gadolinium(III) and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5- Br-PADAP) was studied for delineating optimal conditions for complexation. This reagent can be used for the spectrophotometric determination of Gd(III) in concentrations ranging from 0.04 to 1.2 ppm (a = 1.76(+/- 0.03) x 10(5) (1.(-1) mole(-1). cm). The reaction takes place at a pH between 9.2 and 11.6. In the presence of Triton X-100 this complex is soluble in water. In order to overcome difficulties caused by the presence of other lanthanides, an ion exchange chromatographic technique was used.     

Spectrophotometric determination of uranium(VI) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in a flow-injection system

The direct determination of uranium(VI) by a flow-injection procedure is based on spectrophotometric measurement with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the present of fluoride. The interfering effects of many commonly occuring elements were studied. The calibration curve was linear over the range 0.5–20 mg 1^?1 uranium(VI). The relative standard deviation obtained on a leach liquor containing 10 mg 1^?1 uranium(VI) was 1.9%. The procedure is rapid and convenient, and up to 40 samples can be analysed per hour.     

Atmospheric pressure chemical ionization mass spectrometric and visible spectrophotometric studies of copper(I) and copper(II) complexes with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol.

Complexes of copper(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) formed in aqueous methanol in a wide range of pH (from acidic to alkaline) as well as copper(I)-5-Br-PADAP species formed in methanolic solutions were investigated by spectrophotometry and mass spectrometry. Pseudomolecular and fragment ions created in the atmospheric pressure chemical ionization (APCI) source confirmed the molecular masses of the complexes existing in the solvents and their structures. The structure of the Cu(II) complex with 5-Br-PADAP formed in acidic medium was proposed as CuR(R - H) (where R is the undissociated molecule of the reagent). The binding sites of the two bound reagent molecules were different: in one of them the oxygen atom of the dissociated phenolic group and the nitrogen atom from the azo (-N=N-) group took part in complex formation, whereas in the other only nitrogen atoms from the pyridyl ring and azo group were involved. The complex was stable and could not be reduced to Cu(I) species by use of standard reducing agents (ascorbic acid, hydroxylamine). In alkaline solutions the complex tended to polymerize and precipitated in media containing less than 80% of methanol. The copper(I)-5-Br-PADAP complex was extremely unstable and could be obtained (as a mixture with Cu(II) species) in media free of water or oxygen. For this complex, CuR(2) was proposed as the most probable structure. According to this proposal copper(I) reacted exclusively with nitrogen-containing binding sites and the undissociated phenolic group was not engaged in complex formation. In this system Cu(I)/Cu(II) electron transfer is very rapid, accelerated by a polar environment, e.g. in the presence of water molecules or dissolved oxygen.     

Spectrophotometric procedure for the determination of uranium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol at a nuclear reprocessing facility

A simple method for the determination of uranium in process- and waste-stream samples at a nuclear fuel reprocessing facility that can be applied entirely in a remote environment is described. The method is both sensitive and selective enough to be applicable for almost any uranium determination. Uranium in aqueous samples is extracted as a nitrate complex into 4-methylpentan-2-one (hexone) from an acid-deficient aluminium nitrate salting solution. An aliquot of the hexone extract is then mixed with a solution containing methanol, pyridine and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP). The absorbance of the U(VI)-Br- PADAP complex is measured at 580 nm. The detection limit for uranium is 0.8 μg with the linear range extending to 80 μg. Interference studies, modifications for organic samples and solid-containing samples and process laboratory data are presented.     

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol as a stationary phase in extraction chromatography. Preconcentration of copper,zinc and cadmium ions

The complexes of Cu, Zn and Cd with 2-(5-bromo-2-pyridylazo)-5-diethylamniphenol, formed on PTFE, were re-extracted with isoamyl alcohol followed by a direct spectrophotometric determination. The collection of Cu(II), Zn(II) and Cd(II) from aqueous solutions was found to be quantitative in alkaline medium at pH 8.0–10.0 (Zn), 7.5–9.2 (Cd) and 9.2 (Cu). Concentration factors up to 120 (Cu) and 50 (Zn, Cd) were achieved.     

A study of the direct spectrophotometric determination of uranium(VI) in trialkylamine extracts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

A straightforward spectrophotometric method is described for the determination of uranium(VI) in trialkylamine sulphate extracts in kerosene diluent; 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) is used for colour formation without resort to backextraction into an aqueous phase. The method provides good tolerance to sulphate ion and rapid colour development and appears to be free from interference when applied to extracts from uranium sulphate leach liquors.     

2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚与铕(Ⅲ)络合平衡的双系列线性回归法研究

2- ( 5 -溴 - 2 -吡啶偶氮 ) - 5 -二乙氨基酚 ( 5 - Br- PADAP)是一种灵敏的光度试剂 ,该试剂与铕 ( )的络合比及其稳定常数的研究尚未见报道。本文用双系列线性回归法研究了铕 ( )与 5 - Br- PADAP的络合反应 ,测得铕 ( )与 5 - Br- PADAP形成 1∶ 3的络合物 ,条件稳定常数 ( 1 gβn)为 1 6.5 2 ,最大吸收波长为60 5 nm,摩尔吸光系数为 4.67× 1 0 4 L· mol- 1· cm- 1。     

Selective spectrophotometric determination of thorium(IV) with 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol

A spectrophotometric study of the Th(IV) complex of a new reagent 2-(5-Bromo-2- pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is presented. A reddish brown complex is formed at pH 4.86, and shows maximal absorbance at 580 nm with molar absorptivity of 1.66 × 10⁵ mol⁻¹ cm⁻¹ liter. Beer's law is obeyed over the range 0.0 to 15 μg of thorium. Rare earths ions like La³⁺, Ce³⁺, and Y³⁺ do not interfere because they form complexes with 5-Br-PADAP at higher pH's (>9.94) (1). A new method for determining trace amounts of thorium is proposed, which possesses the advantages of high sensitivity and selectivity.     

Simultaneous determination of gallium and indium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in cationic micellar medium using derivative spectrophotometry.

A new derivative spectrophotometric method for rapid and selective trace analysis of Ga3+ and In3+ and for their simultaneous determination using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in a cationic micellar medium is reported. Molar absorptivity and Sandell's sensitivity of 1:1 Ga+ and In3+ complexes at their lambda(max) 553 nm and 558 nm are: 7.22 x 10(4) l mol(-1) cm(-1) and 5.85 x 10(4) l mol(-1) cm(-1), and 0.96 ng cm(-2) and 1.96 ng cm(-2), respectively. Linearity is observed in the concentration range 0.023-0.700 microg ml(-1) for gallium and 0.076-1.52 microg ml(-1) for indium; IUPAC detection limit is 0.012 and 0.035 ng ml(-1), respectively. These metal ions interfere with the determination of each other. However, 0.07-0.70 microg ml(-1) Ga3+ and 0.115-1.150 microg ml(-1) In3+ could be determined simultaneously when present together by the derivative method without any prior separation. The proposed procedures have been successfully applied for the individual and simultaneous determination of gallium and indium in synthetic binary mixtures, standard reference materials and environmental samples.     

Spectrophotometric determination of zinc with 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol in the presence of anionic surfactant

A sensitive spectrophotometric method for zinc has been established by reacting zinc with 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol (3,5-diBr-PADAP) in the presence of an anionic surfactant, sodium lauryl sulphate. The molar absorptivity is 1.3 x 10(5) l.mole(-1).cm(-1) at 570 nm. The molar ratio of zinc to 3,5-diBr-PADAP is 1:2. Beer's law is obeyed up to 0.7 ppm of zinc. With preseparation of zinc by extraction of its thiocyanate complex, the method has been applied to the determination of zinc in waste water.