Spectrophotometric determination of microamounts of mercury(II) and sulfide ions in aqueous solution

Ammonium (2′,3′-dihydroxy pyridyl-4′-azo)benzene-4-arsonate (DHP-4A) provides a simple, rapid, and sensitive spectrophotometric microdetermination of mercury(II) in aqueous solution. The magenta colored 1:2 metal to ligand complex formed has a molecular extinction coefficient 6.25 × 10⁴ liters mol^?1 cm^?1 at the maximum absorption of 535 nm in highly alkaline medium. Beer's law is obeyed up to 3.8 ppm and Sandell's sensitivity (for an absorbance of 0.001) is 0.0032 μg of mercury(II)/cm². The mercury(II) complexed with DHP-4A has also been used in microdetermination of sulfide ions using ligand exchange reaction. The optimum concentration range of sulfide ions which can reproducibly be determined is 0.16-5.05 μg/10 ml and sensitivity of sulfide ions determination (for an absorbance 0.001) is 7.3 × 10^?4 μg/cm².     

Color Reaction Between 4-(2-Pyridylazo)Resorcinol and Mercury (II) in the Presence of Surfactant,and Improved Spectrophotometric Determinations of Mercury(II) and Cyanide Ion with its Coloring

Abstract

The reactions among 4-(2-pyridylazo)resorcinol (PAR), mercury(II) and/or cyanide ion in the presence of water soluble surfactants alone or combination were systematically investigated at about pH 9. The spectrophotometric determinations of mercury(II) and cyanide ion were investigated by using the PAR-mercury(II)-HPC complex (3:2:2 molar ratio) in the presence of N-hexadecylpyridinium chloride (HPC) alone; calibration graphs were rectilinear in the ranges of 0 – 40 μg mercury(II) and 0 –10 μg cyanide ion in a final 10 ml with the apparent molar absorptivities of 5.9 × 10⁴ for mercury(II) and 2.5 × 10⁴ 1 mol^?1 cm^?1 for cyanide ion at 590 nm. The proposed method had advantages—rapidity, simplicity without solvent extraction, and sensitivity in comparison with reported solvent extraction methods. The interference of foreign ions decreased 1/2–l//4-fold compared with that in the presence of non-ionic surfactant alone.     

Differential Pulse Polarographic Determination of Cd(II) and Pb(II) in Milk Samples after Solid‐Phase Extraction Using Amberlite XAD‐2 Resin Modified with 2,2′‐DPED3P

In the present paper novel column solid phase extraction procedure was developed for the determination of Cd(II) and Pb(II) in cows', goats', ewes', buffalos' and humans' milk samples using newly synthesized reagent 2,2′‐DPED₃P (2,2′‐{[1,2‐diphenylethane‐1,2‐diylidene]dinitrilo}diphenol) for preconcentration and separation prior to differential pulse polarography using amberlite XAD‐2 in the ranges of pH 4.0–5.0. The sorbed elements were subsequently eluted with 10 mL of 2 M HCl elutes were analysed by differential pulse polarography (DPP). The interference of foreign ions has also been studied. Effects of various instrumental parameters are investigated and received conditions are optimized. The total metal concentration of the milk samples in the study area were in the following ranges 0.030–0.090 μg L^?1 of Cd(II), 0.009–0.026 μg L^?1 of Pb(II) respectively. The limits of detections were found to be 0.020 and 0.024 μg L^?1 for Cd(II) and Pb(II) respectively by applying a preconcentration factor ～40. The proposed enrichment method was applied successfully for the determination of metal ions in cows', goats', ewes', buffalos' and humans' milk samples.     

Determination of technetium based on quenching of the fluorescence of some organic compounds,with application to vegetation

Technetium is an effective quencher of the fluorescence produced by 2,5-diphenyloxazole (PPO), 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (POPOP) and 2,2′-pyridil [1,2-dioxo-1,2-bis(2-pyridyl)ethane]. Spectrofluorimetric procedures for 0.01–12 μg Tc ml^?1 with PPO and 0.1–12 μg ml^?1 with 2,2′-pyridil, and a spectrophotometric method for 1–15 μg ml^?1 are described. The distribution of technetium in vegetation is measured by applying the PPO method.     

Spectrophotometric Determination of Palladium(II) with n-Hydroxy-N,N-Diphenylbenzamidine and 1 -(2-Pyridylazo)-2-Naphthol

A spectrophotometric method to determine palladium(II) at trace levels is based on the extraction of palladium(II) as a binary complex with N-hydroxy-N,N′-diphenylbenzamidine (HDPBA) in chloroform at pH 5.0 ± 0.2. The complex shows maximum absorbance at 400 nm with molar absorptivity 6.4 × 10³ L mol^?1 cm^?1. The sensitivity of the Pd(II)-HDPBA complex was enhanced by the addition of l-(2-pyridylazo)-2-naphthol (PAN). The green coloured complex shows maximum absorbance at 620 nm with molar absorptivity 1.58 × 10⁴ L mol^?1 cm^?1. Sandell's sensitivity and the detection limit of the method are 0.0067 μg cm^?2and 0.1 μg Pd(II) mL^?1, respectively. Most common metal ions associated with palladium metal do not interfere. The effects of various analytical parameters on the extraction of the metal are discussed.     

Simultaneous Determination of Nickel(II) and Copper(II) by Second‐Derivative Spectrophotometric Method in Micellar Media

A second‐derivative spectrophotometric method based on zero‐crossing over technique is developed in simultaneous determination of copper(II) and nickel(II) ions. Methylthymol blue (MTB) as a chromogenic reagent and cetyltrimethylammonium bromide as a surfactant were used, and measurements were carried out in buffered solution at pH 6 and at a temperature of 25 °C. The amplitude of derivative spectra was measured at wavelengths of 631.9 and 587.7 nm for the simultaneous determination of Ni²⁺ and Cu²⁺, respectively. Linearity was obtained in the range of 0.5–5.0 μg mL^?1 for both ions in the presence of 0.0–5.0 μg mL^?1 of the other ion as an interfering ion. IUPAC detection limits for Cu²⁺ and Ni²⁺ ions were obtained at 0.48 and 0.43 μg mL^?1, respectively. The proposed procedure has been applied successfully for the simultaneous determination of copper and nickel in synthetic binary mixtures and real samples.     

Trace Detection of Mercury(II) Using Gold Ultra‐Microelectrode Arrays

The electroanalytical detection of trace mercury(II) at gold ultra‐microelectrode arrays is reported. The arrays consist of 256 gold microelectrodes of 5 μm in diameter in cubic arrangements which are separated from their nearest neighbor by 100 μm. The array was utilized in nitric acid using linear sweep voltammetry where a linear response from mercury additions over the range 10 μg L^?1?200 μg L^?1 (10^?8?10^?6 M) was observed with a sensitivity and detection limit of 0.11 nC/μg L^?1 and 3.2 μg L^?1 (16 nM) respectively from using a deposition time of 30 s at ?0.2 V (vs. SCE). This methodology was explored in 0.1 and 1 M chloride media over the mercury range 10 μg L^?1?200 μg L^?1 (5×10^?8?10^?6 M) where similar sensitivities of 0.087 nC/μg L^?1 and 0.078 nC/μg L^?1 were observed with an identical detection limit. The protocol is demonstrated to be useful for the determination of mercury for analysis of environmental water samples.     

O. Carboxyphenylhydrazoethylacetoacetate as an Analytical Reagent for the Determination of Cu(II) and Co(II) in Complex Materials

An extraction‐spectrophotometric method for the determination of trace amounts of copper and cobalt based on their extraction into n‐pentanol with 0. carboxyphenylhydrazoethylacetoacetate (O.CPHEAA) was per formed. Copper was extracted from pH 6.0 – 8.0 and ionic strength 0.5 M – KCl. The maximum absorption of the extracted Cu(II) ‐ O.CPHEAA complex (1:1 & 1:2 species) occurs at 415 nm. The proposed method succeeded in as saying a concentration of 3–63 μg per 10 mL of n‐pentanol (? = 1.25 × 10⁴L mol^?1 cm^?1). The method failed to ex tract cobalt ion into various organic sol vents over a pH range of 2–11. The suggested method is highly selective and sensitive according to a wide scheme of interference studied. Copper in some plant samples was accurately estimated using the suggested method. The obtained results and the results of the AAS method were consistent. The reproducibility test shows a relative standard deviation of 1%. Sandell sensitivity for A = 0.001 is 5 × 10^?3 μg cm^?2.     

Solvent extraction and spectrophotometric determination of iron(II) with 2,2′-dipyridyl-2-quinolylhydrazone

2,2′-Dipyridyl-2-quinolylhydrazone (DPQH) was used for the spectrophotometric determination of trace amount of iron(II) after the extraction process. Iron(II) reacts with DPQH at pH 3.4–4.5 to form a water-insoluble 1:2 complex, which can be extracted with many kinds of organic solvent. The extracted species with benzene has absorption maxima at 473, 504, and 644 nm and obeyed Beer's law over the range 0–14 μg of iron at 504 nm and 0–33 μg at 644 nm. The molar absorptivities at 504 and 644 nm are 3.14 × 10⁴ and 1.30 × 10⁴M^?1 cm^?1, respectively. DPQH is one of the most sensitive reagents for iron(II) and trace amount of iron(II) can be determined in the presence of fairly large amounts of other ions. Possible equilibria involved in the extraction process were also studied.     

Phenylmethoxybis(tetrazolium) ion-association complexes with an anionic indium(III) — 4-(2-pyridylazo)resorcinol chelate

Complex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), phenylmethoxybis(tetrazolium) salt (MBT), water and chloroform. The following MBTs, which differ only by the number of -NO₂ groups in their cationic parts, were used: 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis(2,5-diphenyl-2H-tetrazolium chloride) (Blue Tetrazolium chloride, BT), 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (Nitro Blue Tetrazolium chloride, NBT) and 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2,5-di(4-nitrophenyl)-2H-tetrazolium chloride] (Tetranitro Blue Tetrazolium chloride, TNBT). The composition of the formed ternary complexes was determined, In:PAR:MBT=1:2:2, and the optimum conditions for their extraction found: pH, shaking time, concentration of the reagents and the sequence of their addition. Some key constants were estimated: constants of extraction (K_ex), constants of association (β) and constants of distribution (K_D). BT appears to be the best MBT for extraction of the In(III)-PAR species, [In³⁺(OH)₃(PAR)₂]^4?, (Log K_ex=10.9, Log β=9.8, Log K_D=1.12, R%=92.7%). Several additional characteristics concerning its application as extraction-spectrophotometric reagent were calculated: limit of detection (LOD = 0.12 μg cm^?3), limit of quantification (LOD = 0.40 μg cm^?3) and Sandell’s sensitivity (SS =1.58 ng cm^?2); Beer’s law is obeyed for In(III) concentrations up to 3.2 μg mL^?1 with a molar absorptivity coefficient of 7.3×10⁴ L mol^?1 cm^?1 at λ_max=515 nm.      

Application of the reaction between 2,2′-diquinoxalyl and tin(II) or titanium(III) to kinetic determination of copper and iron

The possibility of application was examined of a reaction between 2,2′-diquinoxalyl and tin(II) or titanium(III) to catalytic determination of copper and iron. The reaction parameters, the influence of the hydrogen peroxide concentration, the hydrochloric acid concentration, and the presence of strange ions on oxidation of the reduced form of 2,2′-diquinoxalyl were tested.The usefulness of the established method was proven for the determination of copper(II) and iron(III) ions in the spectrally pure salts, having the concentration range of those ions 10^?4-10^?5%. The sensitivity of the discussed method is of 0.04 μg/ml.     

An improved spectrophotometric determination of manganese(II) with 1-(2-quinolylazo)-2,4,5-trihydroxybenzene with applications to medicinal plants and chemical reagents

The effects of organic solvent, time and temperature on the colour-forming reaction are described. For nine solvents tested, the molar absorptivities were in the range 2.0×10⁴?6.7×10⁴ mol^?1 cm^?1; best sensitivity was obtained with a 1:1 water/2-propanol solution after a standing time of 35 min; temperature should be controlled to ±2°C. Beer's law was obeyed for 0–1.45 μg ml^?1 Mn(II). The improved method was applied to determinations of manganese(II) in various herbs and chemical reagents; the values found were in the range 5.4–48.4 μg g^?1 in herbs, and 0.001-0.012% (w/w) in reagents.     

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

Abstract

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml^?1) and palladium(II) (0.08 - 1.8 μg ml^?1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.     

Utility of p-chloranilic Acid and 2,3 Dichloro-5,6-dicyano p-Benzoquinone (DDQ) for the Spectrophotometric Determination of Triamterene

Abstract

Two simple and sensitive spectrophotometric procedures are suggested for analysis of triamterene. The first procedure is based on the reaction of triamterene with p-chloranilic acid (p-CA) in methylene chloride to form a highly stable coloured product, exhibiting maximum absorbance at λ 530 nm. Beer's law is obeyed in the range of 40–220 μg.ml^?1 with a mean percentage accuracy of 99.98 ± 0.446. Limit of determination is 20 μg.ml^?1. In the second procedure, the drug is determined via charge transfer complex formation with 2,3 dichloro-5,6-dicyano p-benzoquinone (DDQ) using methylene chloride as a solvent. Here the reaction product has two well defined maxima at 460 nm and 530 nm where each has been utilized for quantitative determination. Beer's law is obeyed in concentration ranges of 25–125 μg.ml^?1 and 25–150 μg.ml^?1 with mean percentage accuracies of 99.92 ± 0.449 and 100.00 ± 0.511 for both maxima. 460 and 530 nm. respectively. Limit of determination is 12.5 μg.ml^?1 at both maxima. Optimum conditions for each procedure have been studied and the stoichiometry of both reactions was ascertained using Job's method of continuous variation. The validity of the suggested procedures was assessed by applying the standard addition technique using the drug capsules. Both procedures are statistically analyzed as compared with BP method for analysis of triamterene (non aqueous titration) revealing good accuracy and precision as indicated by t and F tests.     

Spectrophotometric determination of chloride in non-polar media by the mercury(II) thiocyanate reaction

A simple, rapid and accurate method for the spectrophotometric determination of chloride in non-polar media is described. The method is based on the well-known reaction of mercury(II) thiocyanate with chloride to release thiocyanate, which then reacts with iron(III). The optimum concentrations of reagents for the determination of chloride in 2,2,4-trimethylpentane (iso-octane) and cyclohexane are reported. The molar absorptivity of the complex at 505 nm is 5120 ± 200 dm³ mol^?1 cm^?1 for iso-octane and 5340 ± 340 dm³ mol^?1 cm^?1 for cyclohexane. Beer's Law is obeyed in the range 2 × 10^?7–2 × 10^?5 mol dm^?3 (0.01–1 mg l^?1) chloride.     

An extraction-spectrophotometric determination of palladium with 4-(2-pyridylazo)resorcinol in the presence of diphenylguanidine

A new, sensitive spectrophotometric determination of palladium has been developed, based on the extraction of the red Pd(II) chelate with 4-(2-pyridylazo)resorcinol in the presence of N,N′-diphenylguanidine into n-butanol; the sensitivity of the method according to Sandell is S = 1.12 μg cm^?2, ?₅₃₀ = 9.4 × 10⁴ liters mol^?1 cm^?1, and palladium can be determined at concentrations from 0.21 to 1.91 μg ml^?1.     

A rapid method for the spectrophotometric determination of palladium(II) and osmium(VIII)

Propionyl promazine phosphate is proposed as a new reagent for the rapid spectrophotometric determination of microgram amounts of Pd(II) and Os(VII). PPP instantaneously forms an orange-red 1:1 complex with Pd(II) in sodium acetate-hydrochloric acid buffer of pH 0.8 to 4.0 at room temperature. The reagent also forms an orange-red radical cation with Os(VIII) in 0.5 to 2.0 M hydrochloric acid. The Pd-PPP complex exhibits an absorption maximum at 490–500 nm with molar absorptivity of 7.1 × 10³ liter mol^?1 cm^?1. The Os-PPP radical cation has an absorption maximum at 505–515 nm with molar absorptivity of 2.21 × 10⁴ liters mol^?1 cm^?1. The Sandell sensitivity is 0.022 μg/cm² (Pd) and 0.008 μg/ cm² (Os). Beer's law is valid over the concentration range 0.2 to 21 ppm (Pd) and 0.2 to 4.2 ppm (Os). The proposed method offers the advantages of simplicity, rapidity, and without the need for heating or extraction. The reagent is used for the determination of Pd in the synthetic mixtures corresponding to Pd alloys used in jewelery and Os in osmiridium alloy.     

Copper(II)-lanthanoid(III)-copper(II) trinuclear complexes with N,N′-bis(2-aminopropyl)-oxamido ligand

Six novel μ-oxamido trinuclear complexes, namely Cu₂(oxap)₂Ln(ClO₄)₃ (Ln: La, Pr, Nd, Gd, Yb, Ho), where oxap is N,N′-bis(2-aminopropyl)oxamido, have been synthesized. The complex Cu₂(oxap)₂Gd(ClO₄)₃ was characterized with variable temperature magnetic susceptibility (4—300 K). The exchange integrals J (Cu—Gd) and J′ (Cu–Cu) were found to be 0.83 cm^?1 and ?1.62 cm^?1, indicating that very weakly ferromagnetic spin-exchange interaction operates between Cu(II) and Gd (III) ions.     

Construction of a New Perbromate-Selective Electrode. Kinetic Study of the Iron(II)- Perbromate Reaction and Microdetermination of Iron

Abstract

A perbromate- selective membrane electrode with a liquid membrane of crystal violet-perbromate dissolved in chlorobenzene is described, The liquid membrane electrode exhibits rapid and near Nernstian response to perbromate activity from 10^?5 to 10^?2 M. The response is unaffected by pH in the range 2–10, Major interferences are periodate and perchlorate. A kinetic study of the iron(II)- perbromate reaction was carried out with the perbromate electrode, A potentiometric method is described for the determination of 50–500 μg of iron (II) with relative errors and standard deviations of 1–2%.     

Simultaneous Determination of Cd(II), Cu(II), Pb(II) and Zn(II) in Human Plasma by Potentiometric Stripping Analysis

In this paper, Potentiometric Stripping Analysis (PSA) was simultaneously used to determine the concentrations of trace metals (Zn, Cd, Pb and Cu) in human plasma. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. The selection of the experimental conditions was made by using the experimental‐designed methodology. The optimum conditions of the method includes a 0.2 M HAc‐NaAc buffer mixture (pH 4.5) as supporting electrolyte, and an electrolysis potential of‐1220 mV. The limits of detection (LOD) were obtained 1 μg L^?1 for Zn(II) and Pb(II), 0.5 μg L^?1 for Cu(II) and 2 μg L^?1 for Cd(II) in the studied medium. The good recoveries were obtained for the analysis in human plasma. The method was applied to blood samples, using the method of standard additions and the results were compared with Inductively Coupled Plasma‐Atomic Emission Spectrometry (ICP‐AES) as reference method. Furthermore, a simple digestion protocol of samples is investigated compared to the conventional digestion method.