Controlled-Potential Coulometric Determination of Ruthenium in Ru(OH)Cl3 with Microwave Sample Preparation

A procedure for the controlled-potential coulometric (CPC) determination of ruthenium is proposed. The procedure is based on the redox reaction [Ru(CO)Cl₅]^2–/[Ru(CO)Cl₄(H₂O)]^2– followed by the synthesis of the [Ru(CO)Cl₅]^2– depolarizing complex under microwave irradiation. The procedure was used in the analysis of a domestic commercial Ru(OH)Cl₃ preparation.     

Chromotropic acid-formaldehyde reaction in strongly acidic media. The role of dissolved oxygen and replacement of concentrated sulphuric acid

The procedure for formaldehyde analysis recommended by the National Institute for Occupational Safety and Health (NIOSH) is the Chromotropic acid spectrophotometric method, which is the one that uses concentrated sulphuric acid. In the present study the oxidation step associated with the aforementioned method for formaldehyde determination was investigated. Experimental evidence has been obtained indicating that when concentrated H₂SO₄ (18 mol l⁻¹) is used (as in the NIOSH procedure) that acid is the oxidizing agent. On the other hand, oxidation through dissolved oxygen takes place when concentrated H₂SO₄ is replaced by concentrated hydrochloric (12 mol l⁻¹) and phosphoric (14.7 mol l⁻¹) acids as well as by diluted H₂SO₄ (9.4 mol l⁻¹). Based on investigations concerning the oxidation step, a modified procedure was devised, in which the use of the potentially hazardous and corrosive concentrated H₂SO₄ was eliminated and advantageously replaced by a less harmful mixture of HCl and H₂O₂.     

Determination of UV-absorbing anions in environmental samples by microcolumn high-performance liquid chromatography

The Chromatographic retention and separation of NO ₂ ^- , Br^-, NO ₃ ^- , and I^- anions on a column packed with Nucleosil 100-5 C18 dynamically modified with trimethyloctadecylammonium bromide (TMODAB) was studied using direct UV detection. A procedure was developed for the determination of the above anions in the concentration range 0.06-2500 Μg/L without preconcentration. Sample preparation involved only the elimination of organic impurities (if present) from the test sample. The procedure was used for the determination of NO ₂ ^- and NO ₃ ^- anions in Baikal Lake water and in an aerosol extract.     

GC-MS Discrimination of Citrulline from Ornithine and Homocitrulline from Lysine by Chemical Derivatization: Evidence of Formation of N5-Carboxy-ornithine and N6-Carboxy-lysine

Derivatization of amino acids by 2 M HCl/CH₃OH (60 min, 80 °C) followed by derivatization of the intermediate methyl esters with pentafluoropropionic anhydride (PFPA) in ethyl acetate (30 min, 65 °C) is a useful two-step derivatization procedure (procedure A) for their quantitative measurement in biological samples by gas chromatography-mass spectrometry (GC-MS) as methyl ester pentafluoropropionic (PFP) derivatives, (Me)_m-(PFP)_n. This procedure allows in situ preparation of trideutero-methyl esters PFP derivatives, (d₃Me)_m-(PFP)_n, from synthetic amino acids and 2 M HCl/CD₃OD for use as internal standards. However, procedure A converts citrulline (Cit) to ornithine (Orn) and homocitrulline (hCit) to lysine (Lys) due to the instability of their carbamide groups under the acidic conditions of the esterification step. In the present study, we investigated whether reversing the order of the two-step derivatization may allow discrimination and simultaneous analysis of these amino acids. Pentafluoropropionylation (30 min, 65 °C) and subsequent methyl esterification (30 min, 80 °C), i.e., procedure B, of Cit resulted in the formation of six open and cyclic reaction products. The most abundant product is likely to be N⁵-Carboxy-Orn. The second most abundant product was confirmed to be Orn. The most abundant reaction product of hCit was confirmed to be Lys, with the minor reaction product likely being N⁶-Carboxy-Lys. Mechanisms are proposed for the formation of the reaction products of Cit and hCit via procedure B. It is assumed that at the first derivatization step, amino acids form (N,O)-PFP derivatives including mixed anhydrides. At the second derivatization step, the Cit-(PFP)₄ and hCit-(PFP)₄ are esterified on their C¹-Carboxylic groups and on their activated N^ureido groups. Procedure B also allows in situ preparation of (d₃Me)_m-(PFP)_n from synthetic amino acids for use as internal standards. It is demonstrated that the derivatization procedure B enables discrimination between Cit and Orn, and between hCit and Lys. The utility of procedure B to measure simultaneously these amino acids in biological samples such as plasma and urine remains to be demonstrated. Further work is required to optimize the derivatization conditions of procedure B for biological amino acids.     

Spectrofluorometric determination of zinc with 1,5-bis(2,3-dihydroxyphenylmethylene) thiocarbohydrazone

1,5-Bis(2,3-dihydroxyphenylmethylene)thiocarbohydrazone was synthesized; its ionization constants are reported. A procedure is described for the spectrofluorimetric determination of 5–540 ng ml^?1 zinc in 60/40 (v/v) ethanol/water medium, acetate-buffered to apparent pH 6.5 (λ_ex=400 nm, λ_em=508 nm). Interferences were evaluated and the procedure was applied with good results to the determination of zinc in potable waters (0.3–3 μg ml^?1) and lubricating oils.     

Solvent Extraction of Rhenium(VII) for Preparation of No-Carrier-Added 186Re Saline Solution with High Specific Volume Activity

By using ¹⁸⁸Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO₃ and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of ¹⁸⁶Re from ¹⁸⁶W irradiated by 16 MeV deuterons. No-carrier-added ¹⁸⁶ReO₄ ^– saline solution with high specific volume activity was obtained. The overall recovery yield of ¹⁸⁶Re was about 85%.     

Quantitative separation of carrier-free cerium from fission products

The extraction of Ce (IV) by di-(2-ethylhexyl)-phosphoric acid (HDEHP) has been studied as a function of nitric acid concentration. Using the distribution coefficient data, the optimum conditions for recovery of Ce (IV) from nitric acid medium were arrived at. Under the conditions employed for Ce(IV), a small percentage of Ru was also found to be extracted. Cerium could be selectively stripped from the organic phase with 8M HNO₃/30% H₂O₂ solution. This procedure led to the recovery of¹⁴⁴Ce free of¹⁰⁶Ru. Based on the solvent extraction data, an extraction-chromatographic procedure employing HDEHP (40% w/w) loaded on Amberlite XAD-7 as the stationary phase was developed for the isolation of pure, carrier-free¹⁴⁴Ce from the spent fuel solution.     

Radiochemical measurement of <Superscript>237</Superscript>Np in a solution of mixed radionuclides: Experiences in chemical separation and alpha-spectrometry

A radiochemical procedure is described for the measurement of 0.1 Bq ²³⁷Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of ⁶⁰Co, ⁹⁰Sr and ¹³⁷Cs one hundred times higher. A tracer of ²³⁹Np (milked from ²⁴³Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for ampoule (liquid) and NdF₃ (solid) ²³⁹Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers for ²³⁷Np in NdF₃ sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure.     

Controlled-Potential Coulometric Determination of Iridium in Hexanitroiridate(III) with Microwave Sample Preparation

A procedure is proposed for determining 0.40 to 7.00 mg of iridium (RSD = 1–4%) in Ir(NO₂)^3- ₆. The procedure involved the fast conversion of Ir(NO₂)^3- ₆ into IrCl^2- ₆ by heating it with an HCl solution in a microwave oven and the controlled-potential coulometric determination of iridium using the Ir(IV)/Ir(III) redox system.     

Solvothermal synthesis and luminescence properties of monodisperse Gd2O3:Eu and Gd2O3:Eu@SiO2 nanospheres

A series of uniform, monodispersed Gd(OH)³:Eu³⁺ nanospheres less than 100 nm were successfully synthesized with iron ions as catalyst and DMF as solvent under the solvothermal condition. Cetyltrimethyl ammonium bromide (CTAB) and Polyvinylpyrrolidone (PVP) were performed as co-surfactant during this facile procedure should be changed as A series of uniform, monodisperse Gd(OH)³:Eu³⁺ nanospheres less than 100 nm in diameter were successfully synthesized with solvothermal method. Iron ion was used as catalyst and Dimethylformamide (DMF) as solvent, Cetyltrimethyl Ammonium Bromide (CTAB) and Polyvinylpyrrolidone (PVP) were performed as surfactants. Further calcination process was applied to prepare Gd₂O₃:Eu³⁺ nanoshpheres during this facile procedure.     

Determination of Hydrogen and Oxygen in Chalcogenide Glasses Using a Tandem Laser Mass Reflectron

A procedure was developed for determining hydrogen and oxygen in As–Se and Se–S systems by laser mass spectrometry on a tandem laser mass reflectron. The procedure involves special (both preliminary and in the course of analysis) cleaning of the sample surface with a Q-switched laser. The performance characteristics of the proposed procedure were studied on certified standard reference materials of aluminum alloys, oxygen-doped As₂Se₃, and As₂S₃ with the known absorption at lines of hydrogen-containing impurities. The dependence of the analytical signal on the concentration of gas-forming impurities was linear in the concentration range 10^–5 to 10^–2 mass %. The relative random error of measurements was not worse than 0.21. The detection limit was 8 × 10^–6 mass %.     

Redox Speciation of Inorganic Arsenic in Water and Saline Samples by Adsorptive Cathodic Stripping Voltammetry in the Presence of Sodium Diethyl Dithiocarbamate

This paper describes a new voltammetric procedure for the inorganic speciation of As(III) and As(V) in water samples. The procedure is based on the chemical reduction of arsenate [As(V)] to arsenite [As(III)] followed by the voltammetric determination of total arsenic as As(III) at the hanging mercury drop electrode (HMDE) by adsorptive cathodic stripping voltammetry (AdCSV) in the presence of sodium diethyl dithiocarbamate (SDDC). The reduction step involved the reaction with a mixture of Na₂S₂O₅ and Na₂S₂O₃ in the concentrations 2.5 and 0.5 mg mL^?1, respectively, and the sample heating at 80 °C for 45 min. The linear range for the determination of total arsenic as As(III) in the presence of SDDC was between 5 and 150 μg L^?1 for a deposition time of 60 s (r=0.992). A detection limit of 1.05 μg L^?1 for total As was calculated for the method in water samples using a deposition time of 60 s. The detection limits of 4.2 μg L^?1 and 15.0 μg L^?1 for total As in seawater and dialysis concentrates, respectively, were calculated using a deposition time of 60 s. The relative standard deviations calculated were 2.5 and 4.0% for five measurements of 20 μg L^?1 As(V) as As(III) in water and dialysis concentrates, respectively, after chemical reduction under optimized conditions. The method was applied for the determination of As(III) and total As in samples of dialysis water, mineral water, seawater and dialysis concentrates. Recovery values between 86.0 and 104.0% for As(III) and As(V) added to the samples prove the satisfactory accuracy and applicability of the procedure for the arsenic monitoring.     

Automated synthesis of symmetric integrin αvβ3-targeted radiotracer [18F]FP-PEG3-β-Glu-RGD2

A automated synthesis of symmetric integrin α_vβ₃-targeted radiotracer [¹⁸F]FP-PEG₃-β-Glu-RGD₂ was carried out by multi-step procedure on the modified PET-MF-2V-IT-I synthesizer. Firstly, the prosthetic group of 4-nitrophenyl 2-[¹⁸F]fluoropropionate ([¹⁸F]NFP) was automated synthesized by a convenient three-step, one-pot procedure. Secondly, [¹⁸F]FP-PEG₃-β-Glu-RGD₂ was synthesized by coupling [¹⁸F]NFP with the symmetric RGD-peptide (PEG₃-β-Glu-RGD₂) and purified by a solid-phase extraction cartridge. The radiochemical yields of [¹⁸F]NFP were 35 ± 5 % (n = 10, decay-corrected) based on [¹⁸F]fluoride in 80 min. [¹⁸F]FP-PEG₃-β-Glu-RGD₂ was obtained with yield 40 ± 10 % (n = 5, decay-corrected) from [¹⁸F]NFP within 20 min. The radiochemical purity of [¹⁸F]FP-PEG₃-β-Glu-RGD₂ was greater than 98 %.     

Spectrofluorimetric determination of terbium as its ternary complex with edta and tiron Compositional studies,optimization of fluorescence output and conversion to a flow system

The spectrofluorimetric determination of terbium(III) as its ternary complex with EDTA and Tiron was studied further with regard to composition of the complex and the procedure was optimized by a simplex method. The results suggest a 1:1 molar ratio of terbium to Tiron for the ternary complex. The optimization study indicated that the three chosen variables (pH, and EDTA and Tiron concentration) are not interactive. The method was converted for use in a segmented-flow system with basic Technicon units and a spectrophotofluorimeter as detector. This procedure is satisfactory for the determination of terbium(III) in the range 0.03–0.24 μg ml^?1 at a sampling rate of 30 h^?1. Results were satisfactory for the determination of terbium in lanthanide oxides, mixed oxides, the mineral bastnasite and a green phosphor (Gd_0.96 Ce_0.02 Tb_0.02 F₃).     

A multi-pumping flow system with on-line photochemical conversion and improved sensitivity for phosphorus fractionation in freshwaters

A flow-based procedure with solenoid micro-pumps was developed for phosphorus fractionation (dissolved organic and inorganic phosphorus) in freshwaters. The spectrophotometric detection was based on the formation of molybdenum blue and the organic species were on-line photo-converted to orthophosphate. The analytical response was linear within 10 and 75?µg?L^?1 with a detection limit of 2.0?µg?L^?1 (99.7% confidence level). Coefficient of variation of 1.8% (50?µg?L^?1 P, n?=?20) and sampling rate of 40 determinations per hour were achieved. Per determination, 160?µg (NH₄)₆Mo₇O₂₄, 10?µg SnCl₂, 640?µg K₂S₂O₈ and 10?mg NaOH were consumed, generating 2.0?mL of waste. Slopes of analytical curves obtained for four different organic phosphorus species agreed with those obtained for orthophosphate, indicating quantitative conversion. The results for freshwater samples agreed with those obtained by the AOAC reference procedure at 95% confidence level. The organic matter did not interfere in the photo-oxidative process. The proposed procedure is a fast and environmentally friendly alternative for the phosphorus fractionation in freshwaters.     

Radiochemical procedure for the determination of plutonium isotopes in powdered milk

Summary A radiochemical procedure for the determination of alpha-emitting isotopes of plutonium in powdered milk is proposed. The procedure involves sample dissolution (by HNO₃ and HClO₄), separation by ionic-exchange resin, electrodeposition and alpha-spectroscopy. In order to determine the chemical recovery, ²⁴²Pu was employed as a tracer. A reference material (Marine Sediment IAEA 135) was analyzed to validate such procedure, and to show its reliability. Afterwards, some powdered milk, produced for international trade, was analyzed and chemical recovery was found to be around 95%.     

Arenediazonium Tetrachlorocuprates(II). Modified Versions of the Meerwein and Sandmeyer Reactions

Chloroarylation of unsaturated compounds with arenediazonium chlorides in the presence of CuCl₂ as catalyst involves intermediate formation of arenediazonium tetrachlorocuprates(II) [ArN₂ ⁺]₂ CuCl₄ ^2-. A procedure for preparative isolation of these intermediates was developed, and they were shown to be efficient arylating agents. Reactions of [ArN₂ ⁺]₂ CuCl₄ ^2- with unsaturated compounds gave the corresponding Meerwein products; a mechanism was proposed for these reactions. In polar solvents arenediazonium tetra- chlorocuprates(II) are converted into chloroarenes, presumably through a cyclic transition state.     

Sol-gel synthesis of carbonate-containing zirconium(IV) hydroxide and its sorption properties toward alkaline-earth elements

Carbonate-containing zirconium hydroxide with a CO₂ content of up to 0.5 mol per mole of ZrO₂ was prepared by the sol-gel procedure. The sorption power of the carbonate-containing zirconium(IV) hydroxide toward Sr²⁺, Ca²⁺, and Mg²⁺ ions was studied. The effect of pH and electrolyte concentration on the sorption power was examined.     

242Pu as tracer for simultaneous determination of 237Np and 239,240Pu in environmental samples

A procedure has been developed using ²⁴²Pu as tracer for simultaneous determination of ²³⁷Np and ^239,240Pu in environmental samples. The validity of the method has been demonstrated by ICPMS and a-spectroscopy for up to 10 gram soil and sediment, seawater up to 200 litres. The paper describes a suitable chemical procedure for Np and Pu including a quantitative pre-concentration of neptunium and plutonium, preparation of Np⁴⁺ and Pu⁴⁺, Np(NO₃)₆ ^2- and Pu(NO₃)₆ ^2-. The ratio of ²³⁷Np/²⁴²Pu (or ²³⁷Np/²³⁹Pu) before and after the procedure has been determined using 10 g soil (free from Np and Pu) R _before/R _after = 1.004±3.3% (S.D n = 20) and 1 litre seawater R _before/R _after = 1.019±1.9% (S.D., n = 12). Results from the intercomparison samples IAEA-135, IAEA-381 and from environmental samples are presented.     

Determination of soluble ions and elements in ambient air suspended particulate matter: Inter-technique comparison of XRF, IC and ICP for sample-by-sample quality control

In this paper, we describe a validation procedure for chemical fractionation analysis of elements (Al, As, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sb, Si, Sr, Ti and V) and soluble ions (Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, NH₄⁺, Mg²⁺, Ca²⁺) in suspended particulate matter (PM). The procedure applies three distinct measurement techniques (XRF, IC and ICP-OES) to the analysis of individual samples. The techniques used generate different outputs at different stages in the procedure. This makes it possible to identify the contributions of specific parameters to measurement uncertainty. On this basis, we propose a scheme for controlling the analytical quality of data from individual samples in which inter-technique comparisons is used in the same way many analytical methods use surrogates. We apply this scheme to about 310 samples of PM₁₀ and PM_2.5 identifying and assessing the main factors contributing to measurement uncertainty. This procedure successfully resolved a number of difficulties frequently encountered during the analysis of PM, including lack of appropriate reference materials and the low reliability of alternative techniques of quality control. The results demonstrate the critical importance of sample treatment prior to destructive analysis by IC and ICP.