Spectrofluorimetric flow-injection determination of cerium in carbon and low alloy steels

Cerium can be determined spectrofluorimetrically (_em 350 nm, _ex 260 nm) based on the relatively intense native fluorescence of the cerium(III) aquo-ion. The main potential interference in the analysis of steel from iron(III), cerium(IV) and chromium(VI) are removed by use of a carrier solution containing 2.5% w/v hydroxylammonium chloride. The slight residual interference from iron(II) can be corrected by a matrix matching factor linearly related to the amount of iron present. The calibration graphs are linear over the range 0–7 g ml^–1 based on 250 l injection volumes. The sampling rate was 30 h^–1. The relative standard deviation was 2.0% (n=5) at 3 g ml^–1 cerium. The system has been applied to the determination of cerium in carbon or low alloy steels.     

Extractive spectrophotometric determination of dioxouranium(VI) with the sodium salt of hexamethyleneiminecarbodithioate

The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml^–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×10³ l mol^–1 cm^–1 with Sandell's sensitivity of 0.04 g cm^–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955.     

Simultaneous determination of neodymium and erbium in rare earth mixture with 5,7-dibromo-8-hydroxyquinoline and TX-100 by third-derivative spectrophotometry

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 5,7-dibromo-8-hydroxyquinoline in the presence of octylphenol poly(ethyleneglycol)ether have been studied by normal and third-derivative spectrophotometry. The proposed method is free of interference of other rare earths. The calibration graphs were linear up to 18 g/ml of neodymium and 21 g/ml of erbium (in the final solution). The derivative molar absorptivities are 395 l.mol^–1.cm^–1 for neodymium and 3421.mol^–1.cm^–1 for erbium. The corresponding values of Sandell's sensitivity were 0.36 and 0.49 g.cm^–1, respectively. The relative standard deviations evaluated from ten independent determinations of 2.5 g/ml of neodymium and erbium are 1.5 and 3.8% for neodymium and 1.8 and 4.1% for erbium in absence and presence of 70 g of lanthanum, respectively. The detection limits (signal to noise ratio=2) are 0.23 g/ml for neodymium and 0.30 g/ml for erbium. The method has been used for the determination of neodymium and erbium in mixed rare earths with satisfactory results.     

Simultaneous determination of arsenic and selenium in biological samples by HG-AFS

A new method is proposed for simultaneous determination of traces of arsenic (As) and selenium (Se) in biological samples by hydride-generation double-channel non-dispersive atomic-fluorescence spectrometry (HG-AFS) from tartaric acid media. The effects of analytical conditions on fluorescence signal intensity were investigated and optimized. Interferences from coexisting ions were evaluated. Under optimum conditions linear response ranges above 20 g L^–1 for As and 32 g L^–1 for Se were obtained with detection limits of 0.13 and 0.12 g L^–1, respectively. The precision for elevenfold determination of As at the 4 g L^–1 level and of Se at the 8 g L^–1 level were 2.7 and 1.9% (RSD), respectively. Recoveries of 92.5–95.5% for As and 101.2–108.4% for Se were obtained for four biological samples and two certified biological reference materials. The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for simultaneous determination of As and Se in biological samples.     

Simultaneous determination of cobalt,nickel and iron by multi-wavelength spectrophotometry

A method for the simultaneous spectrophotometric determination of cobalt, nickel and iron based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 390–510 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra, which therefore makes the simultaneous determination of these metallic ions possible without tedious pretreatment. The detection limits afforded by the proposed method range from 0.05 g/ml for Fe and Ni to 0.1 g/ml for Co. Root-mean-squared errors of prediction of 0.085 g/ml for Co, 0.048 g/ml for Ni and 0.1172 g/ml for Fe were obtained using the wavelength range 400–510 nm and 0.147 g/ml for Co, 0.107 g/ml for Ni and 0.127 g/ml for Fe using the wavelength range 420–434 nm. The effect of interferences is studied and the proposed method is applied to analysis for the above elements in synthetic samples and real samples, such as biological materials and alloys.     

Fluorimetric Determination of Europium Based on the Co-Fluorescence System Eu-Y-Sparfloxacin-SDS

A new room temperature fluorescence enhancement system based on complex formation between europium and sparfloxacin in the presence of yttrium in sodium dodecyl sulfate micelle solution has been discovered. The characteristic fluorescence spectra and the effect factors of the fluorescence intensity of the system have been studied in detail. The study results show that the binary complex formed by europium with sparfloxacin in sodium dodecyl sulfate micelle solution can emit intrinsic fluorescence of the lanthanide ion. In the presence of yttrium, the fluorescence intensity of this system was enhanced about 5-fold compared with that of the system without Y³⁺. Under the optimum conditions selected, the fluorescence intensity is a linear function of the concentration of europium in the range of 5.0×10^–11–5.0×10^–7molL^–1, and the detection limit of europium is 1.0×10^–13molL^–1. The system was used for the determination of trace amounts of europium in rare earth samples with satisfactory results.     

Nuclear interferences of uranium and thorium in a reactor neutron activation analysis determination of cerium using the radionuclides141Ce and143Ce

The interference contributions of uranium and thorium to the determination of cerium based on radionuclides¹⁴¹Ce and¹⁴³Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for¹⁴¹Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10^–3 g Ce/g Th, and for¹⁴³Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10^–3 g Ce/g Th.     

Inductively coupled plasma atomic emission spectrometric determination of arsenic in mussel products

Summary A precise, accurate procedure is proposed for the determination of arsenic in mussel products by inductively coupled plasma atomic emission spectrometry. Organic matter is destroyed by dry ashing. Experimental conditions for the determination of arsenic were selected and an interference study was carried out. The methodology developed has a detection limit of 0.1 g g^–1, a relative standard deviation of 3%, and a recovery percentage of 98±2%. The accuracy of the method was checked by analysis of a certified sample of NIST oyster tissue (certified 14.0±1.2 g g^–1; found 14.1±1.1 g g^–1). The proposed procedure was used to analyze real samples of mussel products.     

Spectrophotometric determination of zirconium using robinetin

Summary The complex formation between zirconium and robinetin has been spectrophotometrically investigated and made use of in the determination of zirconium. The complex has been found to contain zirconium and the flavonol in the molar ratio of 12. It obeys Beer's law up to 3.0 ppm of Zr and its stability constant has been calculated to be l.5×10⁹. The reaction is quite sensitive and selective at high concentrations of hydrochloric acid (sensitivity 0.0045 g/cm²).

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Zusammenfassung Zur spektrophotometrischen Bestimmung von Zirkonium wird als Reagens Robinetin empfohlen, das mit Zr einen Komplex im Verhältnis 12 (ZrRobinetin) bildet. Die Stabilitätskonstante wurde zu 1,5 · 10⁹ bestimmt. Das Beersche Gesetz wird bis zu 3,0 ppm Zr befolgt. In stark Salzsauren Lösungen ist die Reaktion empfindlich und selektiv (Empfindlichkeit: 0,0045 g Zr/cm²).

     

Spectrophotometric determination of chromium(III) with 4-(2-thiazolylazo)-resorcinol

Summary The red complex formed between chromium(III) and 4-(2-thiazolylazo)-resorcinol (1 2) at pH 5.0, on heating the reactants to 90° for 45 minutes, is used for Spectrophotometric determination of chromium, the absorbance being measured at 525 nm. Beer's law is obeyed for chromium concentration of 0.06 to 1.1g per ml. Molar absorptivity is 4.98×10⁴ and Sandell sensitivity 0.001g cm^–2. This method has been applied to the determination of chromium content in steel samples.

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Zusammenfassung Der 1 2-Komplex von Chrom(III) mit 4-(2-Thiazolylazo)resorcin bildet sich bei pH 5,0 und 90° C in 45 min. Er eignet sich zur spektrophotometrischen Chrombestimmung. Die Extinktion wird bei 525 nm gemessen. Das Beersche Gesetz ist zwischen 0,06 und 1,1g Cr/ml erfüllt. Die molare Extinktion beträgt 4,98 · 10⁴, die Empfindlichkeit nach Sandell 0,0001g · cm^–2. Die Methode wurde zur Chrombestimmung in Stahlproben angewandt.

     

On-line preconcentration of silver on activated alumina and determination in borehole water by flow injection atomic absorption spectrophotometry

Summary A micro column of activated alumina in the basic form was used in conjunction with flame atomic absorption for the preconcentration and determination of silver in borehole water. The silver was accumulated on the alumina column by pumping sample solution at pH 4 through the column at a rate of 5 cm³ min^-1 for 5 min. By incorporating an injection valve and a simple interfacing device into the system, silver was determined by elution into the nebulizer of an atomic absorption spectrophotometer with 500 l of 2 mol l^-1 nitric acid. Regeneration of the alumina to its basic form was achieved by 0.15 mol l^-1 ammonia solution pumped through the column at 5 ml min^-1 for 2 min. A detection limit of 4 g l^-1 was measured, based on a sample volume of 25 ml. The relative standard deviation was less than ±5% at concentration levels above 10 g l^-1.     

A toxic reagent-free method for normal-phase matrix solid-phase dispersion extraction and reversed-phase liquid chromatographic determination of aldrin,dieldrin, and DDTs in animal fats

A method for the determination of aldrin, dieldrin, DDT, DDE, and DDD contamination in animal fats (beef tallow, lard, and chicken fat) without using toxic reagents is developed, that uses high-performance liquid chromatography after the sample has been prepared by matrix solid-phase dispersion (MSPD) with acidic alumina oxide. A reversed-phase C₁-silica column with a mobile phase of 50% (v/v) ethanol solution (in water) and a photo-diode array detector were used for the determination. Average recoveries of the target compounds (0.2–5.0 g g^–1) ranged from 84–98%, with coefficients of variation of <5%. The limits of quantitation were 0.16 g g^–1 for AD, 0.10 g g^–1 for DD, 0.06 g g^–1 for DDT, 0.07 g g^–1 for DDE, and 0.05 g g^–1 for DDD. No toxic reagents were used at all.     

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.     

Spectrophotometric determination of nitrite in environmental waters using column preconcentration on biphenyl

Column preconcentration methods have been established for the spectrophotometric determination of trace nitrite with sulfanilic acid (SA) orp-aminoacetophenone (AAP) as the diazotizable aromatic amine andN, N-dimethylaniline (DMA) or 1-aminonaphthalene (AN) as the coupling agent, using differention-pairs co-precipitated with biphenyl. Nitrite ion reacts with SA in the pH range 2.0–3.0 and AAP in the pH range 1.7–3.0 in HCl medium to form water-soluble colourless diazonium cations. These cations are subsequently coupled with DMA in the pH range 3.7–6.1 for the SA-DMA system and AN in the pH range 1.7–2.3 for the AAP-AN system to be retained on microcrystalline biphenyl packed in a column. The solid mass is dissolved out from the column with 5 ml of DMF and the absorbance is measured by a spectrophotometer at 420 nm for the SA-DMA system and at 517 nm for the AAP-AN system. The calibration was linear over the concentration ranges 0.3–6.0 g of nitrite in 5 ml of DMF solution (i.e., 0.02–0.40 g/ml in the sample solution) for the SA-DMA system and 0.5–7.0 g of nitrite in 5 ml of DMF solution (i.e., 0.03–0.47 g/ml in the sample solution) for the AAP-AN system. The molar absorptivity and Sandell's sensitivity were respectively 2.63 × 10⁴lmol^–1cm^–1 and 1.75 × 10^–3 g cm^–2 for SA-DMA and 3.28 × 10⁴lmol^–1 cm^–1 and 1.40 × 10^–3 g cm^–2 for AAP-AN. The concentration factors were 4 and 16 for SA-DMA and AAP-AN, respectively. The detection limits were 0.0138 and 0.0175 g/ml NO₂ ^– for SA-DMA and AAP-AN, respectively. Seven replicate determinations of a solution containing 3.5 g of nitrite gave mean absorbances of 0.410 and 0.500 with relative standard deviations of 0.51 and 0.55% for SA-DMA and AAP-AN, respectively. Interference from various foreign ions has been studied and the methods have been applied to the determination of nitrite in environmental samples.     

Katalytischer Nachweis und Bestimmung von Jodspuren mit Hilfe der 3,3′-Dimethylnaphthidin-Hydrogenperoxid-Reaktion

Zusammenfassung Die 3,3-Dimethylnaphthidin-Wasserstoffperoxid-Redoxreaktion wird von Jodid sehr stark katalysiert. Damit kann man bei Anwesenheit von Ameisensäure Jodid selbst in einer Grenzkonzentration von 0,002g/ml nachweisen bzw bestimmen. Dazu eignet sich die Simultankomparationsmethode. Im Konzentrationsbereich von 0,1 bis 0,01g J^–/5 ml beträgt der relative Fehler 3%. Ag⁺, Hg²⁺ oder Bi³⁺ dürfen nicht anwesend sein; andere störende Ionen können mit ÄDTA bzw. Weinsäure maskiert werden.

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Catalytic detection and determination of traces of iodine by means of the 3,3-dimethylnaphthidine-hydragen peroxide reaction

Summary The 3,3-dimethylnaphthidine-hydrogen peroxide redox reaction is strongly catalysed by iodide. Therefore, if formic acid is present, iodide itself may be detected or determined in a limiting concentration of 0.002g/ml. The simultaneous comparation method is appropriate here. In the concentration region from 0.1 to 0.01g I^–/5 ml, the relative error is 3%. Ag⁺, Hg²⁺ or Bi³⁺ may not be present. Other interfering ions can be masked with EDTA or tartaric acid.

     

Studies on the feasibility of production of57Co by alpha bombardment of Mn and Ni targets

We have studied the feasibility of producing⁵⁷Co (271.3 d) via the⁵⁵Mn(, 2n)⁵⁷Co reaction (⁵⁵Mn–100%). The thick target yield of⁵⁷Co in the 28 to 18 MeV energy region was measured as 3.87 Ci/Ah. However, the proximity and overlap of the excitation functions for (, n), (, 2n) and (, 3n) reactions on⁵⁵Mn are such that the production of pure⁵⁷Co in high yields free of⁵⁸Co (70.8 d) and⁵⁶Co (78.8 d) has not been feasible. We have also studied a new method for ancillary production of⁵⁷Co via the reactions⁵⁸Ni(, p)⁵⁷Co and during the course of producing⁶²Zn by⁶⁰Ni(, 2n)⁶²Zn reaction. In this case the yield of⁵⁷Co of reasonable purity has been up to 1 Ci/Ah.     

Photometric determination of palladium with chrome azurol S

Summary Chrome Azurol S permits a simple colorimetric determination of palladium with a sensitivity of 0.4g/cm² (practical) or 0.04g/cm² (Sandell), respectively. Conditions and interferences are described in detail.

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Zusammenfassung Palladium läßt sich mit Hilfe von Chromazurol S auf einfache Weise kolorimetrisch bestimmen. Die praktische Empfindlichkeit der Methode beträgt 0,4g/cm² bzw. 0,04g/cm² nachSandell. Die Arbeitsbedingungen und die durch Fremdionen verursachten Störungen werden angegeben.

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Résumé Le chromazurol S permet un dosage colorimétrique simple du palladium, avec une sensibilité de 0,4g/cm² (en pratique) ou 0,04g/cm² (Sandell) respectivement. On décrit en détail les conditions opératoires et les interférences.

     

Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins

Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL^–1 for bovine serum albumin (BSA), 0.01–6.0 g mL^–1 for human serum albumin (HSA), 0.05–8.0 g mL^–1 for -globulin (-G), and 0.04–4.0 g mL^–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL^–1 BSA, 1.90% for 1.0 g mL^–1 HSA, 1.65% for 1.0 g mL^–1 -G, and 2.32% for 1.0 g mL^–1 ovalbumin.     

Spectrophotometric determination of palladium with 4-(2-pyridylazo)-resorcinol (PAR)

Summary A spectrophotometric method for the determination of palladium is described using 4-(2-pyridylazo)-resorcinol as reagent. The method involves the formation of two red coloured chelates of palladium-PAR at p_H 4.0 and 10.5 respectively. The colour reactions have sensitivity of 0.0085g cm^–2 and 0.0071g cm^–2 for logI ₀/I= 0.001. The effects of p_H, time, order of addition of reagents, temperature etc. have been investigated. The composition of the complexes (metalreagent) have been confirmed by two methods as 11 (at p_H 4.0) and 32 (at p_H 10.5).

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Zusammenfassung Eine spektrophotometrische Methode zur Palladiumbestimmung mit PAR [4-(2-Pyridylazo)-resorcin] wurde beschrieben. Zwei rotgefärbte Chelate werden bei p_H 4,0 bzw. 10,5 gebildet. Die Empfindlichkeit der beiden Reaktionen beträgt 0,0085 bzw. 0,0071g · cm^–2. Der Einfluß von p_H, Zeit, Reihenfolge der Reagenzien, Temperatur usw. wurde untersucht. Die Zusammensetzung der Komplexe entspricht dem Molverhältnis Pd: Reagens= =11 bei p_H 4,0 bzw. 32 bei p_H 10,5.