Study of the absorption spectra of the 4f electron transition of the Nd and Er complexes with 2-isobutylformyl-1,3-dione-indane in the presence of TX-100 and its analytical application

The absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 2-isobutylformyl-1,3-dione-indane and TX-100 have been studied by normal and derivative spectrophotometry. Their molar absorptivities at the maximum absorption bands are about 7.2 (at 571 nm) times greater for neodymium and 13.1 (at 519 nm) times greater for erbium than those in the absence of the complexing agents. Use of second derivative spectra both eliminates the interference from other rare earths and increases the sensitivity from neodymium and erbium. Beers law is obeyed from 020 g/ml for neodymium and 025 g/ml for erbium. The relative standard deviations are 1.2% and 1.6% for 5.0 g/ml of neodymium and 8.0 g/ml of erbium, respectively. The detection limits (signal-to-noise ratio=2) are 0.14 g/ml and 0.20 g/ml. A method for the direct determination of neodymium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.     

Selective determination of neodymium and erbium in mixtures with other lanthanides by second-derivative spectrophotometry of complexes with benzoyl-indan-1,3-dione and cetylpyridinium chloride

The absorption spectra of 4f electron transitions of the neodymium and erbium complexes with benzoyl-indan-1,3-dione and cetylpyridinium chloride have been studied by conventional and derivative spectrophotometry. The second-derivative spectrum has been used to eliminate the interference of the other lanthanides, and to increase the sensitivity by a further factor of 4–6. Beer's Law is obeyed for 6–29 g/ml Nd and 7–33 g/ml Er. The relative standard deviations evaluated from 10 independent determinations of 5.0 g/ml Nd and Er were 1.1% (Nd) and 1.6% (Er). The detection limits obtained from the sensitivity of the calibration graphs and 3s _b, (standard deviation of the blank,n = 11) were 0.63 g/ml Nd and 0.61 g/ml Er. The quantification limits (10s _b) were 2.1 g/ml Nd and 2.0 g/ml Er. A method for the direct determination of neodymium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.     

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.     

Effect of Surfactants on the Immobilization of 4-(2-Pyridylazo)resorcinol on Silochroms

The effect of cationic surfactants (cetyltrimethylammonium bromide, cetylpyridinium bromide, and tetrabutylammonium perchlorate) and a nonionic surfactant (OP-7) on the conditions of the immobilization of 4-(2-pyridylazo)resorcinol (PAR) on three types of silica gel (Silochrom S-120 (200–350 m), Silochrom S-120 (315–500 m), and Silochrom S-80 (200–350 m)) was studied. It was found that OP-7 does not affect the adsorption of surfactants. The effect of cationic surfactants increases in the order tetrabutylammonium perchlorate < cetyltrimethylammonium bromide < cetylpyridinium bromide. The adsorption activity of silica gels increases in the order Silochrom S-120 (315–500 m) < Silochrom S-80 (200–350 m) < Silochrom S-120 (200–350 m). Cetylpyridinium bromide provides full immobilization of PAR on silica gel Silochrom S-120 (200–350 m) in the pH range 2–9.     

Semiautomatic determination of furazolidone and furaltadone by continuous and stopped flow FIA methods

New methods are proposed for the semiautomatic determination of furazolidone and furaltadone by photometric flow injection or stopped flow FIA analysis, on the basis of their alkaline hydrolysis reactions. Linear calibration graphs between 1 and 30 g/ml are obtained for both compounds, the detection limits for furazolidone and furaltadone being 0.20 and 0.26 g/ml, respectively, by flow injection and 0.27 and 0.21 g/ml by the stopped flow approach.     

Simultaneous determination of copper,mercury and lead by first-order derivative spectrophotometry using dithizone as reagent

A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) g present in 40 ml of aqueous phase with detection limits of 5 g/L (Cu) and 20 g/L (Hg and Pb). The R.S.D.s for 100 g/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy.     

Semiquantitative estimation of the mycotoxins citrinin, Ochratoxin A, Aflatoxin M1 and penicillic acid on thin-layer chromatograms with a grey scale

Summary Spots of citrinin, ochratoxin A, aflatoxin M₁ and penicillic acid on thin-layer chromatograms can be semi-quantitatively estimated by using a grey scale, commonly used in photo laboratories. The detection limits are 0.01 g for citrinin, 0.006 g for ochratoxin A, 0.002 g for aflatoxin M₁ and 0.01 g for penicillic acid. Standard curves for these mycotoxins are given.

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Halbquantitative Bestimmung der Mycotoxine Citrinin, Ochratoxin A, Aflatoxin M₁ und Penicillinsäure auf Dünnschicht-Chromatogrammen mit Hilfe eines Graukeils

Zusammenfassung Mit Hilfe eines in Photolabors gebräuchlichen Graukeils können dünnschicht-chromatographische Flecke der obengenannten Mycotoxine halbquantitativ bestimmt werden. Die Nachweisgrenzen betragen 0,01 g für Citrinin, 0,006 g für Ochratoxin A, 0,002 g für Aflatoxin M₁ und 0,01 g für Penicillinsäure. Eichkurven werden angegeben.

     

Determination of sulphathiazole in the presence of sulphametazine by first-derivative solid-phase spectrophotometry

Sulphathiazole in the presence of sulphametazine is determined by a method based on derivative solid-phase spectrophotometry. Both compounds are fixed on a dextran-type cation-exchange gel. The absorbance of the gel, packed in a 1-mm silica cell, is measured directly. The range of application is between 0.20 and 18.0 g/ml of sulphathiazole in the presence of up to 20 g/ml of sulphametazine, the relative standard deviation is 0.6% and the detection limit is 0.05 g/ml. The method has been applied to the determination of sulphathiazole in synthetic mixtures and pharmaceuticals, with recoveries of 95.0 to 102.5%     

Anwendung der Ringofenmethode zum Nachweis einiger Heteroelemente in organischen Verbindungen

Zusammenfassung Ein schnelles und einfaches Mikroverfahren zum Nachweis einiger Heteroatome organischer Verbindungen wurde entwickelt. Nach Aufschluß mit metallischem Kalium werden die entstehenden Ionen mit der Ringofenmethode getrennt und mit empfindlichen Reaktionen nachgewiesen. Nachweisgrenze: 0,5 bis 1g Stickstoff, 1 bis 2g Schwefel, 2 bis 3g Jod, 4 bis 5g Brom, 5 bis 10g Chlor in 0,5 bis 1 mg Einwaage.

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Summary A rapid and simple micromethod was developed for the detection of several hetero-elements in organic compounds. After breaking down the sample with metallic potassium, the resulting ions are separated by the ring oven method and detected by means of sensitive reagents. Detection limits: 0.5 to 1g nitrogen, 1 to 2g sulfur, 2 to 3g iodine, 4 to 5g bromine, 5 to 10g chlorine in samples weighing 0.5 to 1 mg.

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Résumé On a découvert un procédé à l'échelle micro, simple et rapide, pour rechercher certains hétéroéléments dans les composés organiques. Après mise en solution par le potassium métallique, on sépare les ions formés suivant la méthode du four annulaire et l'on effectue la recherche au moyen de réactions sensibles. Limite de dilution: 0,5 à 1g d'azote, 1 àg de soufre, 2 àg d'iode, 5 à 10g de chlore sur 0,5 à 1 mg de prise d'essai.

     

Rapid determination of halogens in milk by instrumental neutron activation analysis

The absolute concentrations of iodine, bromine and chlorine in milk, have been determined by epithermal neutron activation followed by high resolution gamma-ray spectrometry. Two kinds of milk commonly consumed in Israel have been investigated. The concentration of iodine, bromine and chlorine were found to be 0.18–0.30 g/ml, 2.02–2.85 g/ml and 0.65 mg/ml, respectively. The method is fast, selective, accurate and highly sensitive.     

Thermal behaviour or thallium(I) fatty acid salts,I

We have studied the thermal behaviours of the fatty acid (C₁-C₉, C₁₂, C₁₄, C₁₆ and C₁₈) thallium(I) salts.Investigating the dependence of the thermal decomposition reactions on the experimental conditions, we established that they decompose differently depending on the atmosphere, and on the shape and material of the sample holders.We also determined the heat-stable temperature ranges of the compounds in which they can be investigated without any thermal decomposition.The temperatures and enthalpy changes of the polymorphic and phase changes were measured and the corresponding entropy changes were calculated.

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Zusammenfassung Das thermische Verhalten der Thallium(I)-Salze der Fettsäuren mit C₁ bis C₉, C₁₂, C₁₄ und C₁₈ wurden untersucht. Die Temperaturen und Enthalpien der einzelnen polymorphen und Phasenänderungen, sowie die thermische Stabilität der Verbindungen wurden bestimmt. Es wurde festgestellt, daß die zu Ketonen und Gemischt-Ketonen führende thermische Zersetzung in der Schmelzphase von Destillationsprozessen begleitet wird, welche von der Molekülstruktur und von zahlreichen Versuchsbedingungen abhängig sind.

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Résumé Etude du comportement thermique des sels de thallium(I) d'acides gras (de C₁ à C₉, C₁₂, C₁₄ et C₁₈). L'étude de la décomposition thermique en fonction des conditions expérimentales a permis d'établir que les sels étudiés se décomposent différemment suivant l'atmosphère utilisée, ainsi que suivant la forme et la nature des supports échantillons. Détermination des domaines de température où ces composés restent thermiquement stables. Mesure des températures et des variations d'enthalpie des transitions de phase et des transitions polymorphiques et calcul des variations d'entropie correspondantes.

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(I) C₁-C₉, C₁₂, C₁₄, C₁₆, C₁₈. , . , , , .

     

Zur colorimetrischen Bestimmung von 0,0-Dimethyl-2,2-dichlorvinylphosphat (DDVP)

Zusammenfassung Die Farbreaktion von DDVP mit Resorcin wird untersucht und so empfindlich gestaltet, daß damit noch 0,05 g DDVP in 1 ml Lösung bestimmt werden können.In Luft verdampftes DDVP wird in Wasser absorbiert und bis zu einer unteren Grenze von 5 g DDVP im Kubikmeter Luft bestimmt.

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Summary The colour reaction of DDVP with resorcin is investigated and rendered so sensitive that as low an amount as 0,05 g of DDVP in 1 ml solution can be determined.DDVP evaporated in air is absorbed in water and determined down to a bottom limit of 5 g DDVP per cubic metre.

     

Reaction kinetics of alkyl and alkylperoxide radicals

Rate constants for the reaction of alkyl and alkylperoxide radicals in solutions of cyclohexane and tridecane have been measured by flash photolysis and kinetic spectrophotometry methods, respectively.

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Bestimmung von Borspuren in Metallen durch Emissionsspektrometrie mit ICP-Anregung nach Abtrennung als Bors?ure-Ester

Zusammenfassung Zur Bestimmung von Borgehalten im ng/g- und unteren g/g-Bereich in Metallen (Mo, W, Zr, Al, Fe, Co) wurden Verbundverfahren ausgearbeitet, bei denen Bor nach geeignetem Probenaufschluß durch Destillation des Borsäuremethylesters oder durch Ausschütteln als 2-Ethyl-1,3-hexandiol-Komplex abgetrennt und emissionsspektrometrisch mit ICP-Anregung (ICP-OES) bestimmt wird. Mit einer neu entwickelten Kreislaufdestillationsapparatur aus Quarzglas lassen sich Bormengen zwischen 0,02 und 20 g innerhalb von 15 min aus schwefeloder schwefel-phosphorsauren Lösungen von Metallen (Einwaage1g) quantitativ als Methylester abtrennen und in wenigen Millilitern alkalischer Lösung konzentrieren. Das Verfahren ist für alle Metalle anzuwenden, für die man zum Lösen keine HF benötigt. Die Ethylhexandiol-Extraktion wurde für die Abtrennung von 0,02 bis 1 g Bor optimiert, wobei besonders die Matrices Mo, Fe, Zr und Al untersucht wurden. Die ICPOES ist für die Bestimmung von Gehalten an abgetrenntem Bor von 20 ng/ml geeignet. Je nach Matrix und Höhe der Einwaage können somit Nachweisgrenzen von 0,02 g/g erreicht werden.

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Determination of traces of boron in metals by emission spectrometry with ICP after separation as boric acid ester

Summary Procedures for the determination of boron in the ng/g- and low g/g-range in metals (e.g. Mo, W, Zr, Al, Fe, Co) by emission spectrometry (OES) with inductively coupled hf-plasma (ICP) excitation have been investigated. The procedures involve the suitable dissolution of the samples and the separation of boron either by distillation of boric acid methyl ester with a new circulation distillation apparatus or by liquid extraction of the 2-ethyl-1,3-hexanediol complex. By distillation 0.02 to 20 g of boron are separated within 15 min from sulphuric or sulphuric-phosphoric acid solutions ( 1g of sample) and are concentrated in a few milliliters of NaOH. This separation is applicable to all metals which do not require hydrofluoric acid for dissolution. The ethylhexanediol extraction has been optimized for 0.02 to 1 g of boron in solutions of Mo, Fe, Zr, and Al. With ICP-OES concentrations of separated boron of 20 ng/ml can be determined, corresponding to limits of detection down to 0.02 g/g, depending on matrix and sample weight.

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Herrn Professor Dr. W. Fresenius zum 70. Geburtstag gewidmet     

Effect of sampler orifice diameter on dry plasma inductively coupled plasma mass spectrometry (ICP-MS) backgrounds, sensitivities, and limits of detection using laser ablation sample introduction

High backgrounds from polyatomic ions, formed from the argon plasma gas, impurities in the gas supply and atmospheric air entrainment of especially H, C, N, O, and Ar, are a limitation to Inductively Coupled Plasma-Mass Spectrometric (ICP-MS) analysis, especially for analytes with masses below 80 Dalton. When a dry plasma is utilized, instead of the more common wet plasma created when solution nebulization sample introduction is used, the relative contribution of air entrainment becomes more important. In this study, the sample introduction system used was an in-house constructed laser ablation microprobe designed for small volume sampling of geological materials. An enhanced sensitivity VG PQII+S ICP-MS was applied with different sample cone orifice diameters. Background, signal to background ratio, and detection limits are reported for ablated NIST glass reference material (SRM 612). By a reduction of the sample cone orifice diameter from 0.7 mm to 0.5 mm, the background was lowered by factor of ca. 100 in the low mass range and by a factor of ca. 10 in the higher mass range, while similar sensitivities were maintained. The reduced background improved the limits of detection from ca. 1 mg/g/g to <0.5 g/g in 10 m diameter pits and from ca. 100 ng/g to <10 ng/g in larger, 30 m pits.     

Zur Bestimmung N-substituierter Aniline mit Natriumchlorit

Zusammenfassung Es wird eine photometrische Bestimmungsmethode beschrieben für Anilin (40–720 g/ml), Monoäthylanilin (90–1650 g/ml) und Diäthylanilin (100–1600 g/ml) mit Natriumchlorit in äthanolisch-wäßrigen Lösungen, sowie für Diäthylanilin (85–1140 g/ml) und Dimethylanilin (30–330 g/ml) neben den primären und sekundären Aminen in essigsaurer Lösung mit demselben Reagens. Das Verfahren liefert gute Ergebnisse.

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Summary A photometric procedure is described for the determination of aniline (40–720 g/ml), monoethylaniline (90–1650 g/ml), and diethylaniline (100–1600 g/ml) with sodium chlorite in aqueous ethanolic solutions and of diethylaniline (85–1140 g/ml) and dimethylamline (30 to 330 g/ml) in presence of the primary and secondary amines in acetic acid solution using the same reagent. Good results have been obtained,

     

On the use of azo dyes for the spectrophotometric determination of uranium and thorium in mixed solvents

Summary Solochrome Black 6 BN in an acetate buffered medium containing methanol reacts with U(IV) to give a blue complex which permits photometric determination with 5g U/ml to 100g U/ml.In the presence of zinc acetate, uranyl ion also may be spectrophotometrically determined by means of the same dye. From 2g U/ml to 40g U/ml may be determined with a relative error of less than ± 0.05.

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Zusammenfassung Es werden zwei Methoden zur spektrophotometrischen Bestimmung von Uran mittels Solochromschwarz 6 BN beschrieben. Dieser Farbstoff bildet mit U(IV) in acetatgepuffertem, methanolhältigem Medium einen blaugefärbten Komplex, der die Bestimmung von 5 bis 100g U/ml erlaubt.Mit demselben Farbstoff lassen sich auch 2 bis 40g U/ml in Lösungen von Uranylchlorid bestimmen.

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Résumé Le noir solochrome 6 BN en milieu tampon acétique contenant du méthanol réagit avec U-IV en donnant un complexe bleu qui permet le dosage photométrique de 5 g U/ml à 100 g U/ml.En présence d'acétate de zinc, on peut aussi doser l'ion uranyle par spectrophotométrie avec le même colorant. On peut doser de 2 g U/ml à 40 g U/ml avec une erreur relative inférieure à ± 0,05.