Fluoroimmunoassay for neonatal thyrotropin screening in dried blood spots

Conclusions The time-resolved fluoroimmunometric assay for neonatal TSH using Europium fluorescence (DELFIA neonatal TSH, LKB) is a rapid, sufficiently precise, accurate and sensitive method. Because of the better precision in comparision to the RIA method particularly in the lower range the recall rate will be lowered.The advantage of the high sensitivity is the reduced test volume of the very limited material of neonatal blood. The assay described here is therefore an improvement in screening for neonatal hypothyroidism.

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Bestimmung des neonatalen TSH mit einem Fluorescenzimmunoassay

     

Phosphorimetric Detection in HPLC VIA Trivalent Lanthanides: High Sensitivity Time-Resolved Luminescence Detection of Tetracyclines Using Eu3+ in a Micellar Post Column Reagent

Abstract

The detection of tetracyclines in HPLC by sensitized Europium phosphorescence has been reinvestigated using a dedicated LC detector with time-resolved luminescence capability. A micellar Eu³⁺ post column reagent was developed which contained 1% Triton X-100 and 200uM tri-n-octyl phosphine oxide buffered at pH 10.5. This reagent provided optimized time-resolved detection and was found to be compatible with a several mobile phases used in reversed phase chromatography of tetracyclines. The sensitivity and quantitative linearity of the technique was determined using standard fluorometric and time-resolved modes of detection with both grating and filter emission monochromation. Peak areas were linear with concentration from 2 ug on column to the limit of detection. Subnanogram limits of detection were obtained for both tetracycline and oxytetracycline. The relative sensitivity of the technique for compounds tested was oxytetracycline=tetracycline > doxycycline > chlortetracycline > minocycline. The high selectivity of this method promises to be useful in     

FehlererKennung und Programmoptimierung in der ET-AAS durch zeitaufgel?ste Signale (Direkte Elementspurenbestimmung in Harn: Cd, Co, Cr, Ni, Tl, Pb)

Summary The direct determination of trace elements in urines with ET-AA-spectrometry leads to numerous systematic errors. Part of these errors can be discovered by time-resolved signals and can thereby be avoided. Contrary to the assumption that optimal results can be obtained via the signal area, it is often the measurement of the signal height, which is to be given preference (better ratio of atomic absorption signal/background signal). Phosphate-containing matrix modifiers cause systematic interferences; their use should therefore be avoided. The determination of cobalt traces with the ET-AA-spectrometry and with D₂-background correction will always yield wrong values, if samples contain at the same time phosphorous oxygen compounds as well as alkali compounds. Previous Co-determinations which were carried out with this method, should therefore be controlled in a number of biotic matrices. When Zeeman-correction is used, such errors will not occur.     

Time-resolved fluoroimmunoassay of progesterone by Eu-labelled protein-A

Summary A standard curve for progesterone using a solid phase time-resolved fluoroimmunoassay was obtained. The 11-hydroxyprogesterone hemisuccinate bonded to ovalbumin was adsorbed to the wells of polystyrene microtiter strips. After incubation of scalar quantities of free progesterone (from 12 to 5000 pg) with specific antibody and an excess of Eu-labelled protein-A, the wells were washed and the europium bound to the solid phase was measured as a 2-naphthoyltrifluoroacetone chelate using a time resolved fluorometer.

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Zeitaufgelöster Fluorescenzimmunoassay von Progesteron mit Hilfe von Eu-markiertem Protein-A

     

The photoelectric aerosol sensor as a fast-responding and sensitive detection system for cigarette smoke analysis

Summary The combination of the photoelectric aerosol sensor (PAS) and the time programmed sampling of small aerosol volumes within a cigarette puff allows the quantitative time-resolved determination of photoemitting substances in the aerosol. All photoemitting substances contribute to the measured photoelectric (PE) signal. In this comparative study it is shown that the PAS signal correlates well (r=0.94, n=20) with the BaP content. The benzo-a-pyrene (BaP) amounts of the cigarette smoke aerosol were separately determined by in situ synchronous fluorimetry on TLC plates. The absolute detection limit is about 50 pg.

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Photoelektrischer Aerosolsensor als schnell ansprechendes und empfindliches Detektionssystem zur Analyse von Zigarettenrauch

     

Ciclosporin: HPLC routine method with column switching

Conclusion It seems to be a major advantage of the described method that standard HPLC equipment with column switching can be used. The procedure proved to be precise, accurate and specific. According to our experience with CyA determinations in more than 1,000 blood samples, this method is well suited for routine monitoring despite the necessity of sample preparation.

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Ciclosporin: Eine HPLC-Routinemethode mit Säulenschaltung

     

Elektrochemische Massenspektrometrie. On-line Analyse gasf?rmiger Reaktionsprodukte

Zusammenfassung Für kinetische Studien wurde eine schnelle Methode zur Bestimmung von Elektrolysegasen mit einem on-line gekoppelten Quadrupol-Massenspektrometer entwickelt. Gaskonzentrationen im Bereich von 0,005–100 % können mit dieser Methode analysiert werden. Wegen dieses breiten Konzentrationsbereiches wurde für die Peakregistrierung ein programmierter Tischrechner benutzt.

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Electrochemical mass spectrometry. On-line analysis of gaseous reaction products

Summary A rapid method for the determination of electrolysis gas with an on-line coupled quadrupole mass spectrometer has been developed, suitable for kinetic studies. Gases in the range of 0.005–100% can be analysed by this method. Due to the wide concentration range a desk-top computer controlled method was used for peak registration.

     

A New kHz Velocity Map Ion/Electron Imaging Spectrometer for Femtosecond Time-Resolved Molecular Reaction Dynamics Studies

A new velocity map imaging spectrometer is constructed for molecular reaction dynamics studies using time-resolved photoelectron/ion spectroscopy method.By combining a kHz pulsed valve and an ICCD camera,this velocity map imaging spectrometer can be run at a repetition rate of 1 kHz,totally compatible with the fs Ti:Sapphire laser system,facilitating time-resolved studies in gas phase which are usually time-consuming.Time-resolved velocity map imaging study of NH₃ photodissociation at 200 nm was performed and the time-resolved total kinetic energy release spectrum of H+NH₂ products provides rich information about the dissociation dynamics of NH₃.These results show that this new apparatus is a powerful tool for investigating the molecular reaction dynamics using time-resolved methods.     

Thermometric assay of some aldoses

Summary A method is proposed for the determination of milligram amounts of some aldohexoses and aldopentoses. After oxidation using an excess of periodate in acidic solution, the unreacted periodate is determined thermometrically by titration with mannitol, which gives reaction products which cannot react with those already produced. This removes the possibility of errors caused by interaction of the products of the oxidation reaction and the assay reaction. The method gives results as acceptable as those obtained by the Malaprade method, in a shorter time and with better sensitivity, and can be used in industrial samples where methods involving visual detection of the end point cannot be used.

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Thermometrische Bestimmung einiger Aldosen

Zusammenfassung Ein Verfahren zur Bestimmung von mg-Mengen einiger Aldohexosen und -pentosen wird vorgeschlagen. Nach Oxydation mit überschüssigem Perjodat in saurer Lösung wird Perjodat thermometrisch mit Mannit zurücktitriert. Hierbei entstehen Reaktionsprodukte, die mit den bereits gebildeten nicht reagieren. Dadurch werden entsprechende Fehlermöglichkeiten ausgeschaltet. Die erhaltenen Ergebnisse sind denen der Malaprade-Methode vergleichbar; das Verfahren bietet jedoch den Vorteil geringeren Zeitbedarfs und größerer Empfindlichkeit. Es kann für industrielle Proben verwendet werden, bei denen visuelle Endpunktsindikation nicht möglich ist.

     

Mass spectrometrical detection of polymer particles in capsule tissue surrounding joint endoprotheses of polyethyleneterephthalate

Summary Pyrolysis mass spectrometry of synthetic high polymers is described. The method is used to detect polymer wear particles in capsule tissue surrounding endoprotheses with polyethyleneterephthalate parts. An approximation of semi-quantitative determination of the polymer wear will be discussed.

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Massenspektrometrischer Nachweis von Polymerpartikeln in Kapselgewebe, das Gelenk-Endoprothesen aus Polyethylenterephthalat umgibt

Zusammenfassung Die Pyrolyse-Massenspektrometrie der entsprechenden Hochpolymere wird beschrieben und ihre Anwendung auf den Nachweis von Polymer-Abriebteilchen im Kapselgewebe diskutiert. Eine Möglichkeit zur halbquantitativen Bestimmung wird erörtert.

     

Stabilitätsuntersuchungen an Bor-Stickstoff-Sauerstoff-Heterocyclen mittels11B-NMR-Spektroskopie

Boron-11-NMR-spectroscopy is proven to be a powerful tool for the estimation of hydrolytic stabilities of dioxazabora-heterocycles and their corresponding N-Mannich-bases with different carboxamides. In addition this method is used for predicting complex molecular structures of boron-compounds otherwise impossible to elucidate. Several new compounds and¹¹B-NMR-data are described.

     

Estimation of the alkaline earths metals by sequential titration with sodium tetraphenylborate

Summary Alkaline earths metals were titrated potentiometrically in the presence of polyethylene glycol with sodium tetraphenylborate. The sensor was a coated-graphite rod. The method can be used for the sequential estimation of barium, strontium, and calcium. The solubility of the precipitated species decreases with increasing atomic weight of the metals.

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Bestimmung von Erdalkalimetallen durch sequentielle Titration mit Natriumtetraphenylborat

Zusammenfassung Die Erdalkalimetalle wurden potentiometrisch in Gegenwart von Polyethylenglykol mit Natriumtetraphenylborat titriert. Als Sensor diente eine überzogene Graphitstabelektrode. Sequentiell können Barium, Strontium und Calcium bestimmt werden. Die Löslichkeit der Niederschläge nimmt mit ansteigendem Atomgewicht ab.

     

An Optical Fiber-Based Spectrometer for Measurement of Fluorescence Lifetimes

An instrument is described which measures fluorescence intensity and lifetime properties using a single optical fiber for the development of fiber optic chemical sensors. The instrument utilizes a fast-pulse nitrogen laser for excitation and a digital storage oscilloscope to provide time-resolved fluorescence decay curves. The time-resolved measurements permitted the separation of most of the scattered excitation radiation from the sample signal and allowed for analysis of samples exposed to ordinary room lighting. A method for determination of lifetimes from the time-resolved decays was developed based on the time-correlated single-photon counting method. The new method used reference fluorophore solutions to determine the instrument response function, including the influence of the optical fiber, and multiple decays were averaged to improve signal-to-noise and to provide statistical weighting for the analysis. The accuracy of the lifetime analysis was demonstrated by comparison of results for Stern-Volmer quenching of quinine sulfate by chloride ion (slope = 0.115 ± 0.001, int. = 1.04 ± 0.04, r² = 0.9992) with a literature study on the same system (slope = 0.118 ± 0.002, int. = 1.06 ± 0.05, r² = 0.9986). Measurement of the lifetime of pyrene in ethanol gave 17.8 ± 0.9 ns, while the value for coumarin was 3.82 ± 0.45 ns. When mixed together, two lifetimes with values of 17.43 ± 0.73 and 3.68 ± 1.30 ns were determined.     

Application of time-resolved luminescence to dry reagent chemical technology

A time-resolved luminescence method describing the use of terbium(III) in the dry reagent format is presented for the first time. Paper strips previously treated with sucrose are used as solid substrates where terbium(III) is immobilised by adsorption. The strips are stable for at least 6 months and they can be easily stored under a desiccant medium. Only the addition of the buffered sample is required for the analysis. This methodology has been applied to the determination of two local anaesthetics, namely benzocaine and procaine. These compounds release p-aminobenzoic acid after a hydrolysis step in alkaline medium, which reacts to terbium(III) giving a luminescent chelate. The luminescence intensity measurements are obtained at λ_ex 286 and λ_em 545 nm by using the time-resolved mode of the instrument. The method presents a linear range from 1.1 to 21.9 μM and the calculated LOD is 0.4 μM. It has been satisfactorily applied to the analysis of pharmaceutical samples and the recoveries obtained are in the range 88-108%.     

Reactivity of pyrrole pigments. Part 9 MINDO/3 calculations on dipyrrolic partial models of bile pigments

The applicability of the MINDO/3 method is evaluated for calculations on dipyrrolic partial structures of bile pigments. It is shown that this method cannot be used for an accurate conformational analysis. However, when applying the frontier orbital model for reactivity parameters, a good picture of the HOMO and the LUMO distribution can be obtained in this type of molecules.

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Reaktivität von Pyrrolpigmenten, 9. Mitt. MINDO/3-Rechnungen von dipyrrolischen Partialmodellen von Gallenpigmenten

Zusammenfassung Es werden die Einsatzmöglichkeiten von MINDO/3 für den Fall dipyrrolischer Partialstrukturen der Gallenpigmente aufgezeigt. Die Methode ist für eine genaue Konformationsanalyse nicht geeignet. Unter Verwendung der Reaktionsparameter des Frontier-Orbital-Modells läßt sich jedoch ein gutes Bild der HOMO- und LUMO-Verteilung für diesen Verbindungstyp gewinnen.

     

Etude variationnelle d'une double perturbation. Application au calcul des constantes de couplage entre spins nucleaires

The calculation of molecular electronic polarizability tensor components is presented in the CNDO approximation using several methods, on one hand a perturbation calculation, on the other hand a variational method. Results obtained on thirty molecules are used to compare these methods and to discuss their usefulness.

     

Small angle scattering of partially oriented polymers

Summary A general method for the calculation of the small angle scattering pattern of partially oriented polymers with rotational symmetry about the fiber axis is explained. The method can be used with widely varying models for the basic scattering unit.

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Zusammenfassung Es wird eine allgemeine Methode zur Berechnung des Kleinwinkelstreudiagramms von partiell orientierten Polymeren mit Rotationssymmetrie bezüglich der Faserachse angegeben. Als Modell für die streuende Grundeinheit können die verschiedensten Strukturen verwendet werden.

     

Entwicklung eines universellen, preiswerten Interfaces zur Kopplung von Personal-Computern mit Analysenger?ten

Zusammenfassung Es wird ein einfaches und kostengünstiges Verfahren zur Kopplung eines Polarographen mit einem Personal-Computer vorgestellt, womit eine passive Datenübernahme und anschließende mathematische Behandlung der Meßwerte ermöglicht wird. Zur Lokalisation von Peaks wird ein Algorithmus beschrieben, der sich infolge schneller Rechenzeiten durch Echtzeitverarbeitung auszeichnet. Außerdem ist er universell anzuwenden, da er nicht auf mathematischen Gleichungen beruht, die den verwendeten Methoden (z. B.: Polarographie oder Photometrie) zugrunde liegen.

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Development of a universal, low-cost interface for coupling personal computers with analytical devicesPart II. Computer assisted polarography

Summary A simple and inexpensive method is proposed for the combination of a polarographic set with a personal computer. This technique allows a passive data transfer and a following mathematical treatment of the data. An algorithm to locate peaks is developed. Because of the high arithmetic speed it can be used for real time processes. A further advantage of the method described is that this algorithm can be used universally, because it is not based on mathematical equations depending on the experimental method used.

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Teil I: Fresenius Z Anal Chem (1984) 318:509–510

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Nach der Detektion der Peakbasis folgt die Approximation der Basislinie mittels geeigneter Verfahren [5, 10] und die anschließende Berechnung der Peakhöhe bzw. Peakfläche.     

Spectrophotometric estimation of reducing sugars by variation of pH

Summary A Spectrophotometric method of estimation of glucose and maltose using 3,5-dinitrosalicylic acid and measuring the color intensity at two different pH values is described. The concentrations of sugars in unknown solutions are calculated from a linear plot which is obtained when the difference in absorbances at 560 nm for solutions with pH 12.5 and 5.0 (A=A _pH12.5–A_pH5.0) is drawn against concentrations of sugars (up to 3 mg/ 25 ml). This method eliminates the interference caused by the unreacted reagent present in the conventional method. The present method can be used for the estimation of glucose and maltose upto a concentration of 1.5 mg/ml with an error of ±2.0%.

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Spektralphotometrische Bestimmung reduzierender Zucker durch Veränderung des pH-Wertes

Zusammenfassung Die Bestimmung von Glucose und Maltose wird mit 3,5-Dinitrosalicylsäure durch Messung bei zwei verschiedenen pH-Werten durchgeführt. Eine lineare Eichkurve wird bis 3 mg/25 ml erhalten, wenn man die Extinktionsdifferenz für pH 12,5 und 5,0 bei 560 nm gegen die Konzentration aufträgt. Durch dieses Verfahren wird die bei der konventionellen Methode auftretende Störung durch nicht umgesetztes Reagens ausgeschaltet. Bis zu 1,5 mg/ml der Zucker können mit einem Fehler von ±2% bestimmt werden.