Spectrophotometric determination of copper(II) in natural waters, vitamins and certified steel scrap samples using acetophenone-p-chlorophenylthiosemicarbazone

A very simple, highly sensitive and selective spectrophotometric procedure was developed for the determination of copper(II). It is based on the reaction at pH 4–9 between the synthesized acetophenone-p-chlorophenylthiosemicarbazone (A-p-ClPT) and Cu(II) forming a green complex, Cu(II):A-p-ClPT (1:2), that floats quantitatively with oleic acid (HOL) surfactant. It exhibits a constant and maximum absorbance at 600 nm in both aqueous and surfactant layers. Beer’s law is obeyed over the concentration range 0.25–6.35 mg l^?1 with a detection limit of 0.021 mg l^?1 for a standard aqueous solution of Cu(II) with a concentration of 3.82 mg l^?1 (calculated on the basis of 3σ) and molar absorptivities of 5.5 × 10³ and 1.3 × 10⁴ mol l^?1 cm^?1 in aqueous and surfactant layers, respectively. Sandell’s sensitivity was calculated to be 0.244 μg cm^?2 and the relative standard deviation (n = 9) was 0.19%. The different analytical parameters affecting the flotation and determination processes were examined. The proposed procedure has been successfully applied to the analysis of Cu(II) in natural waters, certified scrap steel samples and vitamin samples. The results obtained agree well with those samples analyzed by atomic absorption spectrometry (AAS). Moreover, the flotation mechanism is suggested based on some physical and chemical studies on the solid complexes isolated from aqueous and surfactant layers.     

Polymer membrane sensors for sildenafil citrate (Viagra) determination in pharmaceutical preparations

The construction and performance characteristics of ion selective membrane electrodes for sildenafil citrate (SC) drug (the active component of Viagra) are described. The proposed sensors are based on the formation of the complex ion associates of SC with sodium tetraphenylborate (SC-TPB) and phosphomolybdic acid (SC-PMA) as ionophores in poly vinyl chloride membrane (PVC). Both electrodes SC-PMA and SC-TPB showed a linear and stable potential response with near-Nernstian slope of 55.5±0.35 and 53.5±0.3 mV per decade over a wide range of concentration 10⁻² to 10⁻⁵ M sildenafil with good reproducibility, respectively. The electrodes showed a fast response time of 30 and 40 s. and were used over a wide range of pH 3-6. The selectivity coefficients indicated good selectivity for SC drug over a large number of nitrogenous compounds and some inorganic cations. The proposed sensors are tested for the analysis of SC in pure form, pharmaceutical preparations and blood serum. An average recovery of 98.9-99.5±0.6% and correlation to the existing methods of 0.998 were achieved.     

Flow-injection extraction-spectrophotometric determination of permanganate with the triphenylsulphonium cation

Summary Permanganate can be determined spectrophotometrically at 548 nm after flow-injection extraction into chloroform of the ion-associate triphenylsulphonium permanganate. The carrier stream was a pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream was 0.10% (w/v) triphenylsulphonium chloride. The injection rate was 20 h^–1. The calibration graph is linear up to 40 g ml^–1 and the detection limit is 1.10 g ml^–1 Mn(VII), based on injection volumes of 250 l. The system has been applied to the determination of manganese in steels and a cupro-nickel alloy.     

Sensitive detection and semiquantitative determination of mercury(II) and lead(II) in aqueous media using polyurethane foam immobilized 1,5-di-(2-fluorophenyl)-3-mercaptoformazan

1,5-Di-(2-fluorophenyl)-3-mercaptoformazan (F(2)H(2)Dz) immobilized and plasticized with tri-n-butylphosphate (TBP) polyurethane foam (PUF) were found suitable for the detection of mercury(II) and lead(II) in extremely dilute aqueous solutions. In batch mode of extraction with immobilized F(2)H(2)Dz-foam as low as 0.05 and 0.15 mug ml(-1) of mercury(II) and lead(II), respectively were detected and the colored chelates were found more stable over 72 h. Lower concentrations of these metal ions (相似文献   

Retention profiles of some commercial pesticides, pyrethroid and acaricide residues and their application to tomato and parsley plants

This work deals with the preconcentration of some water soluble pesticides, pyrethroids and acaricides by polyurethane foams. The retention profiles of the tested species were found quickly and reached equilibrium in a few min. Various parameters — e.g. pH, extraction media, shaking time, salt effect, temperature and sample volume — affecting the preconcentration of the tested species by the unloaded foams and tri-n-octylamine and tri-n-methylphosphate treated foams were optimized. The unloaded foams were employed in a column mode to study the quantitative retention and recovery of the tested species. The sorption efficiency and recovery of the compounds by the unloaded foam column were found to be up to 99.5%±2.1. The height equivalent of a theoretical plate for the unloaded foam column was found to be in the range 1.9–2±0.2 mm. The sorption mechanisms of the tested compounds by the foams are discussed. Analysis of N, P, Na, K, Cu, Zn, Mn, Fe, humidity, wet and dry mass of tomato and parsley untreated and sprayed for different time intervals — i.e. 24, 72 and 120 h — with Chlorpyrifos, was carried out.     

Iodometric microdetermination of arsenic and antimony in organic compounds by use of amplification reactions

Summary A six-fold iodometric amplification method is described for the determination of arsenic and antimony in organic compounds. It is based on the oxidation of arsenite (antimonite) with periodate and subsequent reaction of arsenate (antimonate) and iodate with iodide. Average recoveries were 99.8 and 99.5%, average standard deviations 0.22 and 0.34% for As and Sb, respectively.     

Detection and semiquantitative determination of nickel with dimethylglyoxime-loaded foam

Rapid, sensitive and selective detection and semiquantitative determination of nickel in aqueous solution can be obtained by using dimethylglyoxime loaded on polyurethane foam, either by batch or column extractions, the detection limits being 0.05 and 0.01 ppm respectively.     

Extractive liquid-liquid spectrophotometric procedure for the determination of thiocyanate ions employing the ion pair reagent amiloride monohydrochloride

The paper describes analytical methods developed for the production date determination of uranium-based nuclear materials by the measurement of 230Th/234U isotope ratio. An improved sample preparation method for the destructive analysis involving extraction chromatographic separation with TEVA resin was applied prior to the measurement by isotope dilution inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The results obtained were compared with the direct, quasi-non-destructive measurement using laser ablation ICP-SFMS technique for age determination. The advantages and limitations of both methods are discussed.     

Separation of Y from Sr by zirconium vanadate gel ion-exchanger sorbent: kinetics and thermodynamic study

A new zirconium vanadate (Zr–V) ion-exchanger was synthesized and characterized for fast and selective separation procedure of ⁹⁰Y from ⁸⁹Sr. The method was based on ⁹⁰Y(III) sorption from aqueous HCl solution containing ⁸⁹Sr(II) onto Zr–V gel exchanger. The kinetics of Y(III) sorption from HCl solution by Zr–V exchanger was subjected to Weber–Morris, Lagergren, Bhattacharya and Venkobachar, and Bt models. Initially, the uptake of Y(III) onto the exchanger was fast followed by kinetically first-order sorption with an overall rate constant, K _Lager = (3.55 ± 0.03) × 10^?4 min^?1. Film and intraparticle transport are the two steps that might influence Y(III) sorption. The negative values of ΔG of ⁹⁰Y retention dictate that, the process is a spontaneous. The negative values of ΔH and ΔS reflect the exothermic nature of ⁹⁰Y(IIsorption and the random uptake of ⁹⁰Y(III) onto Zr–V sorbent. Zr–V exchanger offers unique advantages of ⁹⁰Y(III) retention over conventional solid sorbents in rapid and effective separation of traces of ⁹⁰Y(III) from Sr. The exchanger was successfully packed in column for an effective separation of ⁹⁰Y.     

Retention profile and selective separation of 90Y from 89Sr using zirconium-vanadate gel packed column

A low cost and selective method has been developed for the separation of trace concentrations of ⁹⁰Y³⁺ from its parent ⁸⁹Sr²⁺. The proposed procedure is based upon complete retention of ⁹⁰Y³⁺ onto zirconium-vanadate (Zr-V) gel ion exchanger packed column from aqueous solutions containing HCl (1.0 × 10^?5mol dm^?3). Under these conditions, ⁸⁹Sr²⁺ species were not retained onto Zr-V sorbent. The retained ⁹⁰Y³⁺ species were then recovered with HCl. The performance of Zr-V sorbent packed column was determined via the height equivalent to the theoretical plates (HETP) and the number of plates (N). Validation of the developed method was checked by calculating the radionuclidic purity in terms of purification factor (P _f = A/A₀) and radiochemical purity of the eluted ⁹⁰Y from the column. Zr-V sorbent packed column offers unique advantages of retention and quantitative separation of ⁹⁰Y from retention over conventional solid sorbents in rapid and effective separation of trace concentration of ⁹⁰Y³⁺ from ⁸⁹Sr²⁺ in their aqueous equilibrium media.