Application of a rapid scanning photodiode-array spectrophotometer to the continuous determination of nickel and cobalt

A computer-processed linear photodiode-array spectrophotometer is used for the continuous and simultaneous determination of nickel and cobalt in the process water of a storage battery. Disodium ethyl-bis(5-tetrazolylazo) acetate is used as the pnotometric reagent. The interference of copper(II) is eliminated by reduction and complexation of copper(I).     

A rapid method of determination of specific surface areas

An apparatus and a method for the rapid determination of specific surface areas are described. The method is based on low temperature adsorption of nitrogen from the air and requires determination of the adsorbed gas at two relative pressures. The accuracy of the method, as compared with the BET technique, is ±9% for the adsorbents studied.

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. . , BET, ±9% .

     

Synthesis of functional monolayer surfaces for rapid radiometric determination of plutonium

Glass or silicon substrates functionalized with a monolayer of carbamoylmethylphosphonate (CMP) ligands effectively bind tetravalent actinides from optimized mineral acid solutions to enable rapid, high quality radiometric assay by alpha spectrometry. The observed alpha spectra compare favorably with the highest quality electroplated samples. The CMP-functionalized surfaces have been used to develop simplified analytical methods to determine plutonium from complex mixtures.     

GC determination of traces of acetaldehyde in aqueous matrix: A rapid Headspace method

Summary A Headspace GC method for the determination of traces of acetaldehyde in aqueous matrix has been developed. The method is simple, rapid, repeatable, and its results are linear from 25ppb (detection limit) to 300ppb or higher. This method is proposed for the quantification of acetaldehyde released from plastics into aqueous foods.     

A rapid and precise heterometric method for the determination of traces of phosphoric or arsenic acid with nitron and molybdate

The precipitation of phosphomolybdate or arsenomolybdate with nitron was studied by heterometry at various acidities. A rapid and precise heterometric method is presented for the determination of 0.03–0.08 mg of phosphorus (or 0.06–0.16 mg of arsenic). Foreign salts can be tolerated often in 100–200-fold molar amounts. No interference is caused by Ca, Ba, Mg, Zn, Cr³⁺, Fe, Mn, Co, Ni, Al, U(VI), Cd, Cu, Pb, Hg²⁺, Ag, Zr or Th. Iodide, silicic acid, tartrate or pyrophosphate can also be tolerated.The titration time is 10–15 min and the error is usually less than 1%.     

An enzymatic method for the rapid measurement of the hemoglobin A1c by a flow-injection system comprised of an electrochemical detector with a specific enzyme-reactor and a spectrophotometer

A flow-injection analytical (FIA) system, comprised of an electrochemical detector with a fructosyl-peptide oxidase (FPOX-CET) reactor and a flow-type spectrophotometer, was proposed for the simultaneous measurement of glycohemoglobin and total hemoglobin in blood cell. The blood cell samples were hemolyzed with a surfactant and then treated with protease. In the first stage of operation, total hemoglobin in digested sample was determined spectrophotometrically. In the second stage, fructosyl valyl histidine (FVH) released from glycohemoglobin by the selective proteolysis was determined specifically using the electrochemical detector with the FPOX-CET reactor. The FIA system could be automatically processed at an analytical speed of 40 samples per hour. The proposed assay method could determine selectively only the glycated N-terminal residue of β-chain in glycohemoglobin and total hemoglobin in blood cell. The enzymatic hemoglobin A_1c (HbA_1c) value calculated by the concentration ratio of the FVH to total hemoglobin, was closely correlated with the HbA_1c values certified by the Japan Diabetic Society (JDS) and the International Federation of Clinical Chemistry (IFCC).     

A rapid method for simultaneous determination of carbon and hydrogen in petroleum products,with a specific infrared detector

Summary A new carbon-hydrogen analyser is described. It differs from others in that it uses two specific infrared detectors. The basic principle of this analyser is a flash combustion of the sample in oxygen in a vertical furnace, and the water and carbon dioxide are measured with the two infrared detectors in series, the signals from the detectors being automatically integrated. The analyser determines carbon and hydrogen in petroleum products simultaneously in 3 min. The standard deviation for samples weighing about 1 mg is 0.3% for carbon (85%) and 0.06% for hydrogen (12%).

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Eine Schnellmethode zur gleichzeitigen Bestimmung von C und H in Erdölprodukten mit einem Infrarot-Detektor

Zusammenfassung Ein neues Gerät zur C-H-Bestimmung wurde beschrieben, das sich von bisher bekannten Apparaten durch zwei Infrarot-Detektoren unterscheidet. Die Probe wird im Sauerstoffstrom in einem senkrechten Rohr verbrannt, Wasser und Kohlendioxid werden nacheinander in zwei Infrarotgeräten gemessen. Die Detektorsignale werden automatisch integriert. Die Analysenzeit für Erdölprodukte beträgt ca. 3 min. Für Einwaagen von ca. 1 mg beträgt die Standardabweichung 0,30% für Kohlenstoff (85%) und 0,06% für Wasserstoff (12%).

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Spectrophotometric determination of plutonium with chlorophosphonazo III

Summary Plutonium(IV) forms a Chlorophosphonazo III complex in 0.5–2M hydrochloric acid. Maximum absorbance occurs at 620 and 685 nm. Beer's law is obeyed over the range of 0–50g per 10 ml and the molar absorptivity is 3.7×10⁴ mol^–1 cm^–1 at 690 nm. Plutonium can be determined in the presence of fluoride, sulfate and phosphate. However, lanthanides, thorium, uranium and zirconium interfere seriously.

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Zusammenfassung Plutonium(IV) bildet in 0,5-bis 2-m Salzsäure mit Chlorphosphonazo III eine Komplexverbindung, deren Absorptionsmaxima bei 630 und 685 nm liegen. Bis 50 g/10 ml entspricht die Farbe dem Beer'schen Gesetz; die molare Extinktion bei 690 nm beträgt 3,7·10⁴l·Mol^–1·cm^–1. Plutonium kann damit in Gegenwart von F^–, SO₄ ^2– und PO₄ ^3– bestimmt werden. Lanthanide, Th, U und Zr stören jedoch ernstlich.

     

A rapid calibration method for the determination of traces of oxygen by 14-MeV neutron activation analysis

A dual axis rotation irradiation system has been used in the development of a calibration method for the determination of oxygen in almost any matrix by 14-MeV neutron activation. The method allows the correction of matrix effects which arise from neutron removal and γ-self absorption, thus providing an accuracy of ± 2% for the oxygen analysis. The experimental results are interpreted on the basis of theoretically calculated mass absorption coefficients and neutron removal cross-sections.     

Pyrohydrolysis for the rapid determination of chlorine traces in silicate and non-silicate minerals and rocks

Summary This simple method for the determination of chloride takes a total time of 15 min. Samples are mixed with silica in the ratio 11, and the chloride is liberated in an induction furnace by pyrohydrolysis within ca. 10 min. The chloride is collected in a 0.020 M sodium-hydroxide solution. This solution is filled up to 200 ml with twice distilled water and absorption is measured with ferric ammonium sulphate and mercury(II) thiocyanate solution by a Zeiss Elko II photometer. Analysis of three international reference samples show excellent accuracy with a standard deviation of less than 4% (e.g. for a chloride content of 117 ppm in Andesite AGV-1).

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Pyrohydrolyse zur schnellen Bestimmung von Chlorspuren in silicat- und nichtsilicathaltigen Mineralien und Gesteinen

Zusammenfassung Diese einfache Methode zur Bestimmung des Chloridions benötigt eine Gesamtzeit von 15 min. Die Proben wurden mit Kieselsäure im Verhältnis 11 vermischt und in einem Induktionsofen 10 min lang pyrohydrolysiert. Das entstandene HCl wurde in einer 0,020 M Nariumhydroxidlösung aufgefangen. Diese Lösung wurde mit zweifach dest. Wasser auf 200 ml aufgefüllt, mit Eisenammoniumsulfat- und Quecksilberthiocyanatlösung versetzt und deren Absorption mit einem Zeiss-Elko II-Photometer gemessen. Die Analysen von 3 internationalen Referenzproben zeigen eine hohe Präzision mit einer relativen Standardabweichung von weniger als 4% (z. B. für einen Gehalt von 117 ppm Chlor in Andesit AGV-1).

     

A flow system with a conventional spectrophotometer for the chemiluminescent determination of lactic acid in yoghurt

A flow-based analytical procedure for lactate determination in yoghurt by chemiluminescence using a conventional UV-Vis spectrophotometer as detector is described. The radiation source was switched off. The flow cell was machined in acrylic with a 1 mm path length and a 80 mm(2) surface and was positioned 2 mm distal of the photodetector (100 mm(2) sensible area) in order to improve detection. The flow network computer-controlled comprised a set of three-way solenoid valves assembled to implement the multicommutation approach. The chemiluminescence was obtained by using the reaction of luminol with hydrogen peroxide, catalyzed by hexacyanoferrate (III) after enzymatic reaction with lactate. The lactate oxidase enzyme was immobilized on porous silica beads (glass aminopropyl, SIGMA). The signal generated by the spectrophotometer reaction was read by the microcomputer and stored as a function of time for further treatment. Immobilization condition, enzyme concentration, temperature, pH, stability of the enzymatic reactor, and flow rates were investigated. The feasibility of the system was ascertained by analyzing a set of yoghurt samples. Results were in agreement with those obtained by a conventional method (Boehringer UV-Kit), and no significant difference at 95% confidence level was observed. A linear response within 10-125 mg l(-1)l-lactate, a 1.9% standard deviation (n=10), and an analytical throughput of 55 determinations per hour were achieved.     

Problems of plutonium and uranium determination

The experience with the determination of plutonium and uranium in the samples of nuclear fuel obtained during a 10-years period of the activity of the Central Control Laboratory of the Nuclear Research Institute at e is evaluated. The paper describes the principles of the methods used and the reproducibilities and accuracies of the results obtained with the aid of the titrimetric methods used for the determination of plutonium and uranium.     

A routine method for the determination of plutonium in urine with a low detection limit

A radiochemical method for the determination of plutonium in urine is described. The steps involved are a) co-precipitation of plutonium, b) wet ashing, c) hydrolysis, d) extraction from 2M HNO₃ into capillary polypropylene columns coated with tri-n-octyl phosphineoxide 0.5M in toluene, and e) back-extraction of plutonium from the organic phase, f) electroplating onto stainless steel disks and spectrometry, since plutonium is extracted together with small amounts of uranium naturally occurring in urine. High quality deposits for spectrometry are obtained because iron interference is eliminated before back-extraction. The radiochemical recovery of²³⁹Pu is 55.6±7.5% and the detection limit is 1.0 mBq per liter of urine.     

Colorimetric determination of traces of tin with dithiol

Procedures are given for the determination of traces of tin with dithiol (4-methyl-1,2-dimer-captobenzene) by visual color comparison and absorptiometric measurement, with special reference to silicate rocks, meteorites, and sulfides. The sensitivity is 1 p.p.m. Sn with 0.5 g of sample. Tin is separated by distillation of the bromide. Provision is made for the presence of selenium.     

Spectrophotometric determination of traces of selenium with diaminobenzidine

Diaminobenzidine is suitable for the spectrophotometric determination of traces of selenium. The reaction is very sensitive, the molecular extinction coefficient being as high as 10,200. The reaction is specific, the most common ions causing no perturbation. The procedure is especially valuable for the determination of traces selenium in tellurium and in sulfur, provided that the latter is present in the sulfate form.     

Individual determination of uranium and plutonium in a single aliquot

Studies on the individual potentiometric determination of uranium and plutonium in a single aliquot have been initiated recently in our laboratory. It was required to adapt the reported procedures (for the precise determination of uranium and plutonium individually when present together in a sample) at various stages to make them suitable for the successive application of the procedures to the same aliquot. Two alternative schemes are proposed in the present work. In the first, plutonium is determined by HClO₄ oxidation followed by the determination of total uranium and plutonium by Zn(Hg) reduction. In the second, plutonium is determined by AgO oxidation following the determination of total uranium and plutonium by Zn(Hg) reduction. Amount of uranium is computed in both cases from the difference of two determinations. Precision for the assay of plutonium and uranium was found to be ±0.25% and ±0.35%, respectively, at milligram levels.     

Development of rapid bioassay method for plutonium

For the internal dosimetry of plutonium, a urine bioassay method is very useful but requires several days to obtain the result of the analysis. To shorten the time required for the urine bioassay, a rapid method for plutonium analysis using the ICP-MS system was developed. In this chemical procedure, a microwave oven was applied for sample digestion, and an extraction chromatography resin was used for the separation of plutonium. The measurement time was extremely reduced by application of the ICP-MS as compared to alpha-spectrometry. The total analysis time was about 12 hours and the detection limit was 0.3 mBq/sample. The short analysis time and the low detection limit indicate that this method is useful not only for special monitoring but also for routine monitoring.     

A titrimetric method for the sequential determination of thorium and plutonium

A method for the sequential determination of thorium and plutonium has been developed. In the sample solution containing thorium and plutonium, thorium is first determined by complexometric titration with EDTA and then in the same solution plutonium is determined by redox titration employing potentiometry. Prior to the determination of plutonium, EDTA is destroyed by fuming with concentrated HClO₄. Thorium is determined at 10 mg level and plutonium at 1 mg level with precision and accuracy of better than ±0.5%.