Showing papers in "Mikrochimica Acta in 1982"
TL;DR: In this paper, solid sampling with graphite-furnace atomic absorption is used to obtain accurate results in the determination of trace elements in different NBS Standard Reference Materials (SRLs).
Abstract: Microanalysis using mechanized solid sampling with graphite-furnace atomic-absorption gives accurate results in the determination of trace elements in different NBS Standard Reference Materials. Analytical conditions are optimized by use of the method of standard additions, and all capabilities of a microcomputer controlled graphite furnace, such as matrix modification by oxygen ashing, temperature ramping and maximum power heating for atomization are used. Direct calibration against acid standards is possible.
20 citations
TL;DR: In this paper, the percentage of saponins in garlic, onion and leek was determined, applying the densitometric method on thin layer chromatograms, previously proposed5.
Abstract: From plant material (Allium sativum, Allium cepa, Allium porrum), extracts characterised by a high haemolytic activity were obtained. In the raw saponin preparation the percentage of saponins in garlic, onion and leek was determined, applying the densitometric method on thin layer chromatograms, previously proposed5. Purified crystalline or oil-like saponin preparations were hydrolysed or complexed with cholesterol. The isolated sapogenins were identified by mass spectrometry, IR, NMR and UV analysis. The following sapogenins were found: sitosterol, gitogenin, oleanolic acid and amyrin.
19 citations
TL;DR: In this paper, the Tl(III)-Bromo-Rhodamin B intensive Farbkomplexe bilden, wesentlich vermindert werden, and the zulassigen Hochstkonzentrationen fur Storelemente wurden tabelliert.
Abstract: Zur zuverlassigen Erfassung von Thalliumspuren (≥20 ng Tl absolut) in wasrigen, silikatischen und biologischen Proben wurden die herkommlichen spektralphotometrischen Bestimmungsmethoden kritisch diskutiert und die besonders nachweisstarke und selektive, extraktionsphotometrische Methode uber den Tl(III)-Bromo-Rhod-amin-B-Komplex eingehend auf Fehler untersucht. Durch Schutteln der thalliumhaltigen organischen Phase mit 0,5 M HBr-Losung, die 0,2% Hydroxylamin enthalt, konnten Storungen von Elementen (Au, Hg, J), die ebenfalls mit Rhodamin B intensive Farbkomplexe bilden, wesentlich vermindert werden. Die zulassigen Hochstkonzentrationen fur Storelemente wurden tabelliert.
18 citations
TL;DR: In this paper, the amount and distribution of terpenoid components are useful aids to chemotaxonomy for Nasutitermitinae termites, which can have tetracyclic, tricyclic and bicyclic skeletal structures with various degrees of oxygenation.
Abstract: Mono- and diterpenoid components of severalNasutitermitinae soldier secretions have been characterised by gas chromatographymass spectrometry. Patterns in monoterpene distribution are useful, but not sufficient for chemotaxonomic purposes without determination of the diterpene distribution. Diterpenoids are structurally complex and can have tetracyclic, tricyclic and bicyclic skeletal structures with various degrees of oxygenation. The relative retention indices for several identified diterpenoid compounds have been determined on OV-1 and OV-17 columns. The amount and distribution of the terpenoid components are useful aids to chemotaxonomy forNasutitermitinae termites.
16 citations
TL;DR: The thermal behavior of some metal chelates of dipropyl- and dibutyldithiocarbamic acids has been investigated to determine their suitability for gas-chromatographic determination of trace metals as mentioned in this paper.
Abstract: The thermal behaviour of some metal chelates of dipropyl- and dibutyldithiocarbamic acids has been investigated to determine their suitability for gas-chromatographic determination of trace metals. Good determinations can be achieved within the range 50–1000 ng and perhaps even lower, on carefully constructed, short glass capillary columns.
14 citations
TL;DR: In this article, a method avoiding the analytical problems of aluminium determination in human plasma is described, and normal values for healthy persons and levels for dialysis patients are given for both adults and children.
Abstract: Determination of aluminium in human plasma is of great interest in monitoring dialysis patients under oral aluminium therapy. Flameless atomic-absorption is chosen as the method because of the low normal levels of this non-essential trace element. A method avoiding the analytical problems of aluminium determination in human plasma is described. Normal values for healthy persons and levels for dialysis patients are given.
14 citations
13 citations
TL;DR: Sandell's sensitivity calculated from the calibration curve at 30 min after the start of the reaction is 1.43×10−1 ng cm−2 as discussed by the authors, which is the highest known sensitivity.
Abstract: Cadmium(II) accelerates the complex formation reaction of manganese (II) withα, β, γ, δ-tetra(p-sulfonatophenyl)porphine (H2TPPS4). Cadmium(II) concentration as low as 10−7 mol dm−3 can be determined from the decrease in absorbance at 413 nm (λmax of H2TPPS4) at a fixed time after the start of the reaction of manganese(II) with H2TPPS4. After the separation of lead(II) by coprecipitation of manganese(IV) oxide, the method is highly selective and is free from interference of most substances usually encountered. Sandell's sensitivity calculated from the calibration curve at 30 min after the start of the reaction is 1.43×10−1 ng cm−2.
13 citations
TL;DR: In this article, it has been found that mononitro-aromatic compounds can be used as quite sensitive reagents for determination of reducing sugars, and use of 2-, 3- and 4-nitrobenzoic and 3-nitrogen-benzenesulphonic acids has been investigated.
Abstract: It has been found that mononitro-aromatic compounds can be used as quite sensitive reagents for determination of reducing sugars, and use of 2-, 3- and 4-nitrobenzoic and 3-nitrobenzenesulphonic acids has been investigated. Reduction of these reagents with sugars gives a yellow product which can be determined spectrophotometrically. The sugar (0.5–7 mg) is heated with fixed concentrations of reagent, base and sodium potassium tartrate for a prescribed time, at 100° C. The method can also be used for determination of the number-average molecular weight of dextran fractions if the molecular weight is not too high.
11 citations
TL;DR: In this article, the elektrochemische Verhalten einiger Flavonoide an einer glasartigen Kohlenstoffelektrode wurde sowohl mit der Gleichstromvoltammetrie wie also mit der cyklischen Voltammetri untersucht.
Abstract: Das elektrochemische Verhalten einiger Flavonoide an einer glasartigen Kohlenstoffelektrode wurde sowohl mit der Gleichstromvoltammetrie wie auch mit der cyklischen Voltammetrie untersucht. Dabei zeigte sich, das das Oxydationspotential dieser Verbindungen von der Zahl der Hydroxygruppen, von deren Stellung (ortho oder meta) und davon abhangt, ob eine Hydroxygruppe durch eine Methoxygruppe ersetzt wurde. Weiters wurde gefunden, das die Anzeige der Flavonoide bei niedrigem pH-Wert hoher als im alkalischen Milieu ist. Mit Hilfe der cyklischen Voltammetrie konnten die Vorgange bei der elektrochemischen Oxydation dieser Verbindungen gedeutet werden. Fur Dihydroquercetin und Hesperitin wird ein Reaktionsmechanismus angegeben.
9 citations
TL;DR: In this paper, a Monte-standard neutron-activation analysis of large-volume water samples without preliminary chemistry is applied to the multielement determination of trace inorganic species in pure water, river water, urban effluent, etc.
Abstract: Mono-standard neutron-activation analysis of large-volume water samples without preliminary chemistry is applied to the multielement determination of trace inorganic species in pure water, river water, urban effluent, etc. The accuracy, precision and sensitivity have been assessed by analysing a standard reference material, a water sample from a round-robin analysis and pure waters. The method is applied to investigate the behaviour of trace inorganic species in the course of the cleaning process in an urban sewage treatment plant. The distribution of the elements in the effluents and stably suspended materials has been systematically analysed and the behaviour of the elements in the system discussed.
TL;DR: In this paper, the effects of resin weight and the intensity of ultrasound and mechanical stirring on ion exchange equilibria were investigated in terms of its cavitation action on the film diffusion.
Abstract: The ultrasound increases the ion exchange rate in comparison with the undisturbed. Contrary to a previous report in the literature, however, its effect on ion-exchange equilibria is less than that of mechanical stirring. The effects of resin weight and the intensity of ultrasound and mechanical stirring are reported. The ultrasound effect is discussed in terms of its cavitation action on the film diffusion.
TL;DR: In this article, vegetables, canned food, and marine fishes were analyzed for lead, mercury, cadmium and thallium by amperometry and by atomic absorption spectrometry.
Abstract: Vegetables, canned food, and marine fishes were analyzed for lead, mercury, cadmium and thallium by amperometry and by atomic absorption spectrometry. Masking agents were used in the amperometric titration procedure in order to determine the concentration of the individual metal ions. The results from these two methods have been compared and found to be in good agreement with each other.
TL;DR: In this article, a kinetic method for determination of traces of Ce(IV) based on the oxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2, 6-disulphonate is described.
Abstract: A kinetic method for determination of traces of Ce(IV), based on the oxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2, 6-disulphonate is described. The reaction is monitored by means of the fluorescence of the oxidation product (λ
ex=525nm,λ
em=585 nm), and allows determination of 0.02–0.37 ppm Ce(IV). The proposed method has few interferences.
TL;DR: In this article, the trien-tartrate was used as duel masking agent for copper and triethylenetetramine (trien) for iron with 1,10-phenanthroline.
Abstract: Cupric ion forms a very stable complex with triethylenetetramine (trien). It has a very weak absorption at 400–460 nm, however, the ferroin shows a very strong absorption at 480–520 nm. The use of trien-tartrate as duel masking agents for copper has been proved to be successful, and is superior to EDTA or citrate-EDTA in the determination of iron with 1,10-phenanthroline. The colour reaction may be accelerated at 60° for 10 min. The new method has been applied to the analysis of U. S. NBS standard solder alloy samples for iron.
TL;DR: In this article, a simple method for the determination of barium in natural waters by flameless atomic absorption spectrometry using the carbon rod was proposed, which was applied to samples from the Atlantic Ocean and from Araruama Lake.
Abstract: A simple method for the determination of barium in natural waters by flameless atomic absorption spectrometry using the carbon rod is proposed. Barium in highly salted waters is previously separated from the interfering ions by ion-exchange chromatography, using Dowex 50 W-X8 resin, and eluted with 0.1M EDTA solution. Mineral waters with low salinity are transferred directly to the furnace and the standard addition method is performed. The detection limit is 90 pg Ba for 10νl injections. The method was applied to samples from the Atlantic Ocean and from Araruama Lake. Barium in commercially available waters was also determined.
TL;DR: In this article, a method for the determination of traces of lead and copper in foods by a microcomputer-processed atomic absorption spectrometry with a molybdenum micro-tube atomizer is described.
Abstract: A method is described for the determination of traces of lead and copper in foods by a microcomputer-processed atomic absorption spectrometry with a molybdenum micro-tube atomizer. Accurate results of lead and copper are obtained by atomization in the presence of thiourea. Thiourea contributes to a highly reproducible atomization profile and reduction of interferences from concomitant elements in foods. Solid samples are digested with nitric acid in the Uni-seal decomposition vessel, while liquid or water-soluble samples are directly atomized.
TL;DR: In this article, the 1∶2 complex obeys Beer's law for manganese concentration of 0.04-1.4μg per ml, has molar absorptivity 4.176 x 104 and Sandell sensitivity 0.0013μg cm−2.
Abstract: Manganese forms a red chelate with 4-(2-thiazolylazo)-resorcinol at pH 8.8 (borate buffer), and absorbance is measured after 30 s, at 540 nm in the presence of 20%tert-butyl alcohol (by volume). The 1∶2 complex obeys Beer's law for manganese concentration of 0.04–1.4μg per ml, has molar absorptivity 4.176 x 104 and Sandell sensitivity 0.0013μg cm−2. The formation constant (logK) is found to be 9.32, and relative standard deviation ±0.22%. Of the 48 ions studied for interference, only Co(II), Zn(II), Cd(II), Pb(II) and EDTA2− are found to interfere. This method has been applied for the determination of manganese content in alloy steels.
TL;DR: In this paper, a rontgenographische Mikrobeugungsverfahren entwikkelt, von denen zwei vorgestellt wurden.
Abstract: Zur Bestimmung der kristallographischen Orientierung, der Gitterparameter und der Kristallstruktur von Mikrobereichen der Werkstoffoberflache stehen eine Reihe von rontgenographischen und elek-tronographischen Verfahren zur Verfugung. Eine Gegenuberstellung ihrer Leistungsfahigkeit zeigt, das sie hinsichtlich ihrer Einsatzmoglichkeiten groseren Einschrankungen unterworfen sind. Deshalb wurden neue rontgenographische Mikrobeugungsverfahren entwikkelt, von denen zwei vorgestellt wurden. Zur Untersuchung ausgewahlter Kristallite in kompakten Proben ist das Drehschwenkverfahren geeignet, bei dem durch parallele monochromatische Rontgenstrahlung die Schnittlinien der zu den Netzebenenscharen gehorenden Beugungskegel auf einem Film kontrastreich abgebildet werden. Die Geometrie dieser Beugungsfiguren wurde erklart und die Bestimmung der kristallographischen Orientierung und der Gitterparameter am Beispiel von Si und α-Fe erlautert. Zur Untersuchung von Mikrobereichen polykristalliner Werkstoffe wird ein Rontgenmikrodiffraktometer mit ringformigem Proportionalzahlrohr verwendet, das die in einem Debye-Scherrer-Ring enthaltene Intensitat auf einmal registriert. Mit dieser Anordnung wurde der Verlauf der mechanischen Spannung vor einer Risspitze und an den Risufern quantitativ ermittelt.
TL;DR: In this article, the effects due to nitrate concentration, acidity, extracting solvent and equilibration time are reported for the extraction of silver(I) with acetoxime, methylethylketone oxime, 3-pentane oxime and 4-heptanone oximes.
Abstract: The extraction of silver(I) with acetoxime, methylethylketone oxime, 3-pentanone oxime and 4-heptanone oxime was studied. The effects due to nitrate concentration, acidity, extracting solvent and equilibration time are reported. Methylethylketone oxime in dichloromethane was found to be a highly efficient extracting solution for silver(I) in weakly acidic 0.5M sodium nitrate solution.
TL;DR: In this article, a catalytic constant-current potentiometric titration with a cathodically polarized graphite indicator electrode was applied for determination of mercury or organomercuric compounds in some pharmaceutical products (Exomycol, Unguentum Hydrargyri, Salyrgan and Merthiosal).
Abstract: Catalytic constant-current potentiometric titration with a cathodically polarized graphite indicator electrode was applied for determination of mercury or organomercuric compounds in some pharmaceutical products (Exomycol, Unguentum Hydrargyri, Salyrgan and Merthiosal). The Ce(IV)-As(III) system in the presence of sulphuric acid was used as indicator reaction; it is catalysed by the first excess of titrant, potassium iodide. Special attention was paid to sample decomposition. The methods are simple and fast, and can be recommended for determination of mercury or organomercuric compounds. The results are in good agreement with those of other methods.
TL;DR: In this article, a calibration graph for bismuth, lead, silver and tellurium was constructed using aqueous standards, and data on the slopes and quality of the graph were presented.
Abstract: To ascertain whether calibration graphs constructed with aqueous standards can be employed for the determination of volatile trace elements in metals at concentrations <10μg/g, calibration graphs have been produced for bismuth, lead, silver and tellurium by introducing milligram masses of standard steels, nickel-base alloys and coppers, or microlitre volumes of aqueous standards, into either an induction furnace or a resistively heated furnace. Data are presented on the slopes and quality of the calibration graphs. Quantitative determinations of trace elements in metals by use of aqueousstandard calibration graphs proved possible only in isolated cases, though semiquantitative results (i. e. within 15% of actual content) could be obtained for bismuth and lead in the alloys mentioned, preferably with the induction furnace, but accurate results could not be obtained for the determination of trace concentrations of silver and tellurium in the metals. It is best to construct a calibration graph with metal standards of the same type as the samples to be analysed.
TL;DR: In this paper, an ion-association osmium complex with Rhodamine 6G (R6G) and toluene was used for the spectrophotometric determination of Osmium in mixtures of platinum metals.
Abstract: Osmium separated by distillation as OsO4 and absorbed in 8–10M HCl is converted into\(OsCl_6 ^{2 - } \). When an acid solution (approx. 1M HCl) containing microgram amounts of osmium (as\(OsCl_6 ^{2 - } \)) and Rhodamine 6G (R6G) (about 2.5×10−4M) is shaken with toluene, a sparingly soluble ion-association osmium complex quantitatively precipitates at the phase boundary or on the walls of the separatory funnel. An acetone solution of this compound is then used for the spectrophotometric determination of osmium. Beer's law is obeyed. The molar absorptivity at 530 nm is 4.0×105l·mole−1 ·cm−1. The effects of other platinum metals have been examined. Ruthenium interferes to only a very limited extent. The component ratios in the isolated compound were determined, and the formula\([(R6G^ + )_2 (OsCl_6 ^{2 - } ) \cdot 2(R6G^ + Cl^ - )]\) is proposed for the adduct. The method has been applied to the determination of osmium in mixtures of platinum metals. When xylene is used as flotation agent, osmium separates at a different acidity (pH 1.3–5), as a simple ion-association complex\([(R6G^ + )_2 (OsCl_6 ^{2 - } )]\). The spectrophotometric method involving xylene is less sensitive (by a factor of about 2).
TL;DR: In this paper, a case of co-ordinatively saturated and unsaturated activatorcatalyst complexes being active has been observed for the first time in the field of activated catalytic analytical reactions with Mn(II)-catalysedp-phenetidine oxidation by periodate, with 1,10-phenanthroline as activator.
Abstract: A case of co-ordinatively saturated and unsaturated activatorcatalyst complexes being active has been observed for the first time in the field of activated catalytic analytical reactions with Mn(II)-catalysedp-phenetidine oxidation by periodate, with 1,10-phenanthroline as activator. An analytical procedure for determining trace amounts of Mn(II) has been developed on the basis of this catalytic reaction. The new method has better analytical characteristics than the one using no activator.
TL;DR: In this paper, the authors used flame atomic absorption spectroscopy for the quantitative determination of thallium and found an optimal pH of about 6 while for the simultaneous extraction of the three elements lead, cadmium and thalium, a pH-value of about 5 is preferred.
Abstract: Flame atomic absorption spectroscopy can be used for the quantitative determination of thallium. For this, thallium is to be separated from source material if source has complex matrix structure. Since thallium is present in the,μg/g region an extraction procedure is adapted. This procedure consists of complex formation of thallium with APDC and DDDC and the extraction of the complexes into liquid phase using MIBK as solvent. For the extraction an optimal pH is found to be about 6 while for the simultaneous extraction of the three elements lead, cadmium and thallium a pH-value of about 5 is preferred. For quantitative analysis by flame atomic absorption spectroscopy the detection limit for thallium in the organic extract was found to be 0.07μg/ml.
TL;DR: In this paper, the determination of nitrogen in zirconium by chargedparticle activation analysis is described, where the 14N(α,αn)13N and the 14 n(p,α)11C reactions were used.
Abstract: The determination of nitrogen in zirconium by charged-particle activation analysis is described. The14N(α,αn)13N and the14N(p,α)11C reactions were used. The13N activity was separated from matrix activity as ammonia by steam-distillation after dissolution of the sample in dilute hydrofluoric acid. The11C activity was separated as carbon dioxide by dissolution of the sample in a mixture of concentrated sulphuric acid, sodium fluoride and potassium periodate, followed by oxidation of the evolved gases with a copper oxideiron oxide-kaolin mixture and trapping of the carbon dioxide in dilute sodium hydroxide solution. The chemical yield of both separations was investigated. The nuclear interference of boron can be neglected, in view of the low boron content. Alpha- and proton-activation yielded the following results for BCR reference materials (alpha-activation results first): CRM 21: 24.6±3.3 and 25.9±0.8μg/g (certified value: 26.4±2.5μg/g); CRM 56: 12.0±1.1 and 10.5±0.3μg/g (certified value: 11.7±1.7μg/g); CRM 57: 11.2±0.3μg/g (alpha-activation) (certified value: 11.9±1.8μg/g).
TL;DR: In this paper, simple, direct and sensitive low temperature phosphorimetric methods for the determination of monuron, diuron, and fenuron in EPA solvent are described.
Abstract: Simple, direct, and sensitive low temperature phosphorimetric methods for the determination of monuron, diuron, and fenuron in EPA solvent are described. The minimum detectable amounts are 0.2, 0.1, and 0.02 p. p. m. for monuron, diuron, and fenuron respectively. The ranges in linearity of the analytical calibration graphs are 0.2–10, 0.1–7.5, and 0.1–20 p. p. m. for monuron, diuron, and fenuron respectively. The procedure for monuron has been applied to the analysis of a solid commercial formulation.
TL;DR: In this article, DmQH has been used as a solvent extracting agent for Cu(II, Ni(II), and Co(II) into the solvent MIBK.
Abstract: Diacetyl-mono-(2-quinolylhydrazone), DmQH, has been studied as a solvent extracting agent for Cu(II), Ni(II), and Co(II) into the solvent MIBK. Cu(II) extracts as the Cu(CO)+ ion in a 1∶1 complex with DmQH to form the neutral species [Cu(OH)(L)]. Since there is no variance of the distribution coefficient with the perchlorate ion present, no ion pairing exists. At pH values greater than 6, copper may be extracted with an efficiency of 95% into MIBK while there is no extraction of this complex into benzene. The extractions of Ni(II) and Co(II) show some dependence with pH; however, their efficiencies are less than 50%. At pH values greater than 6.5, gelatinous precipitates form which coagulate at the interface between the two solvents.
TL;DR: In this article, potentiometric titration with lead nitrate was used to determine chatechol on the microscale by titration of lead ion-selective electrodes and a single junction reference electrode.
Abstract: Catechol was determined on the microscale by potentiometric titration with lead nitrate. Solutions were buffered to pH 9.5 with borate buffer. Emf's were monitored with a lead ion-selective electrode and a single junction reference electrode. Up to an eightfold excess of hydroquinone or resorcinol can be tolerated.
TL;DR: In this article, a method was developed for the determination of microgram amounts of niobium in stainless steels with the reagent 5-chloro-8-hydroxy-7-iodoquinoline in citric acid medium.
Abstract: The determination of niobium at levels of 0.02% and above is required in certain types of stainless steels and niobium stabilized steels. A method has been developed for the determination of microgram amounts of niobium in stainless steels with the reagent 5-chloro-8-hydroxy-7-iodoquinoline in citric acid medium. The effects of heating time, pH, reagent concentration and other variables have been studied. The system obeyes Beer's law over the concentration range investigated. The optimum concentration range for measurements in 10-mm cells is 1.0–10.0μg of niobium ml−1. The molar absorptivity of the complex is 5.143 x 103l·moli−1·cm−1. The interferences from foreign ions have been evaluated. The stoichiometry of the complex ML2 (metal:ligand) was confirmed by Job's continuous variations and mole ratio methods.