Determination of digoxin in human-serum

Summary Four immunological assays (RIA, ELISA, EMIT, FPIA) for digoxin were characterized with respect to reproducibility, detection limit, selectivity, and accuracy, followed by the comparison with HPLC. Afterwards the serum samples of nearly 60 patients were analyzed by these five methods.It could be shown, that the reproducibility at 2 g/l was fairly good for all methods. Reliable analysis in the lower concentration range (< 1 g/l) was difficult with two assays, because of insufficient detection limits. There was a marked cross-reactivity to other digitalis glycosides. Moreover, correlation between the immunological methods and in comparison to the HPLC-method was low.

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Bestimmung von Digoxin in HumanserumVergleich einiger immunologischer Assays mit einer vorgeschlagenen HPLC-Referenzmethode

     

Disopyramide analysis using REMEDi: comparison with EMIT and conventional high performance liquid chromatographic methods.

REMEDi (Rapid EMErgency Drug identification; Bio-Rad) is an automated high performance liquid chromatographic (HPLC) system designed to detect, identify and measure a range of basic and neutral drugs in 0.5-1.0 mL of urine or plasma/serum. We have evaluated REMEDi in the analysis of the antiarrhythmic drug disopyramide in patient samples. The specimens were also analysed by a conventional HPLC method, based on solvent extraction and UV detection (254 nm), and by EMIT. There were good correlations between the results obtained with each method (r = 0.91 or greater). REMEDi gave a lower mean result than EMIT [means +/- SD (mg/L): REMEDi 2.64 +/- 1.10, EMIT 3.14 +/- 1.51; t = 4.0, p less than 0.01; n = 25], but there were no other significant differences in mean results. The principal disopyramide metabolite, mono-N-desalkyldisopyramide, did not interfere in any method. Clearly REMEDi can be used for therapeutic drug monitoring of disopyramide provided enough sample is available.     

Routine monitoring of carbamazepine and carbamazepine-10,11-epoxide in plasma by high-performance liquid chromatography using 10-methoxycarbamazepine as internal standard

Carbamazepine and carbamazepine-10,11-epoxide were separated by high-performance liquid chromatography (HPLC) with acetonitrile-water as mobile phase, and detection was effected by UV absorption at 215 nm with a total retention time of less than 10 min. Plasma samples were extracted with dichloromethane and 4 M sodium hydroxide, and 10-methoxy-carbamazepine was added as internal standard. Other commonly used anticonvulsant drugs present in plasma showed no significant interference. The within-batch coefficient of variation for carbamazepine was 4.9% and carbamazepine-10,11-epoxide 5.9%. Between-batch coefficients of variation were 3.7% and 5.3%, respectively. Mean recovery for carbamazepine was 100.2% and for carbamazepine-10,11-epoxide 100.6%. This HPLC method was compared with both an enzyme immunoassay procedure (EMIT) and a gas-liquid chromatographic (GLC) method. Correlation coefficient between HPLC/EMIT for carbamazepine was 0.983, HPLC/GLC carbamazepine 0.988 and HPLC/GLC carbamazepine-10,11-epoxide 0.981.     

Determination of vitamin E in different biological samples by high-pressure liquid chromatography

Summary The different methods for the determination of vitamin E in all types of biological materials are reviewed. The following subjects are dealt with: isolation of the vitamin from biological samples, foodstuffs and pharmaceuticals; instrumental aspects (injection, reversed-phase HPLC, straight-phase HPLC); standardization; detection limits.

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Bestimmung von Vitamin E in verschiedenen biologischen Proben durch HPLC

Zusammenfassung Die Übersicht behandelt folgende Aspekte: Isolierung des Vitamins aus biologischem Material, Lebensmitteln und Pharmazeutica; instrumentelle Probleme (Injektion, reversed-phase und straight-phase HPLC); Standardisierung; Nachweisgrenzen.

     

Chromatographie par complexe de transfert de charge. Application à l'analyse d'hydroliquéfiats du charbon par HPLC

Résumé L'analyse de coupes lourdes (huile de distillation sous vide et huile issue du séparateur à chaud) provenant de l'hydroliquéfaction catalytique du charbon a été réalisée par mise en ouvre de différentes techniques chromatographiques. L'identification des principales structures résulte de l'application de la chromatographie par couplage de transfert de charge en mode HPLC et des spectroscopies UV et de masse.

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Donotor-acceptor complex chromatography —Application to analysis of coal liquefaction products by HPLC

Summary A Vacuum gas oil and the corresponding residue of a coal liquefaction product were investigated by means of HPLC and MS. Nearly a complete identification was performed by chromatographic, UV-spectroscopic methods and MS.

     

Anwendungsmöglichkeiten der HPLC bei der Trennung,Isolierung, Identifizierung und quantitativen Bestimmung von Substanzen aus komplexen Stoffgemischen—am Beispiel von Carbonsäuren in Natriumaluminatlaugen aus dem Bayerprozeß der Aluminiumoxidgewinnung

Zusammenfassung Es wird die Anwendung der Hochdruckflüssigchromatographie (HPLC) in Bezug auf die Identifizierung und quantitative Bestimmung von Carbonsäuren in Aluminatlaugen aus dem Bayerprozeß beschrieben. Die Vorgehensweise besteht in folgenden Teilschritten: Optimierung von HPLC Phasensystemen zur Trennung von synthetischen Gemischen von Carbonsäuren, Aufarbeitung der Aluminatlauge, semi-präparative Isolierung von Substanzen, Identifizierung auf flüssigchromatographischem Wege und durch Massenspektrometrie, quantitative Bestimmung durch Peakhöhenauswertung mit Hilfe externer Standards.

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HPLC of carboxylic acids in sodium aluminate liquors from the Bayer process

Summary The paper describes the application of high performance liquid chromatography (HPLC) to the identification and quantitation of carboxylic acids in aluminate liquors from the Bayer process. The procedure comprises the following consecutive steps: optimization of HPLC phase systems employing synthetic mixtures of carboxylic acids, clean-up of the liquor, semi-preparative isolation of substances, identification by means of HPLC and mass spectrometry and estimation based on peak height measurement using external standards.

Herrn Prof. Dr. I. Halász zum 60. Geburtstag gewidment.     

Bestimmung von Thiolverbindungen durch selektive Fluorescenzderivatisierung und HPLC

Zusammenfassung Es wird ein Verfahren zur schnellen und empfindlichen Bestimmung thiolgruppenhaltiger Verbindungen durch Bildung fluorescierender Derivate und Hochdruckflüssigkeits-Chromatographie (HPLC) beschrieben. Dazu wurden die Reaktionsbedingungen für eine selektive Umsetzung der Sulfhydryle mit 5-Dimethylaminonaphthalin-1-sulfonylaziridin (Dansylaziridin) untersucht. Die gebildeten Derivate sind stabil und zeigen starke Fluorescenz. Zur Detektion der einzelnen Verbindungen nach Hochdruckflüssigkeits-Chromatographie wird ein Fluorescenzmonitor verwendet. Die Nachweisgrenzen für thiolhaltige Aminosäuren liegen im pmol-Bereich.

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Determination of thiol-containing compounds by selective fluorescence-derivatization and HPLC

Summary A fast and sensitive method for the determination of thiol-containing compounds by formation of fluorescent derivatives and high pressure liquid chromatography (HPLC) is described. The conditions for the selective reaction of thiol compounds with 5-dimethylaminonaphthalene-1-sulfonylaziridine were investigated. The derivatives are stable and give high fluorescence yields. After HPLC separations a fluorescence detector was used to achieve maximum sensitivity. The detection limits for thiol containing amino acids are in the pmol range.

     

Determination of cyclosporine A in whole blood: comparison of a chromatographic method with three different immunological methods

Cyclosporine A is potent immunosuppressive agent characterized by a narrow therapeutic range, inter- and intra-individual variability and a lack of correlation between drug dosage and blood levels. In view of these facts, blood levels of CyA should be routinely monitored to assess organ rejection and toxicity.

We evaluated CyA as well as its metabolites (AM9, AM19, AMl, and AM4N) in whole blood samples from 117 patients using commercially available immunological assays (AxSYM, EMIT, Dimension) and HPLC.

Cross-reactivity of the immunological assays was evaluated using different concentrations of the CyA metabolites (in vitro cross-reactivity) and by statistical analysis of patient data (in vivo cross-reactivity). Cross-reactivity was seen in all immunological assays, with differences in in vitro and in vivo cross-reactivity.

The statistical analysis showed a classical correlation between HPLC and AxSYM of r² = 0.89, HPLC versus EMIT of r² = 0.93, and HPLC versus Dimension of r² = 0.93.

The percentage metabolite cross-reactivity (%) by immunological assays for four metabolites at two concentrations each (250 and 1000 ng ml⁻¹) was lowest with the Dimension assay.

Of the immunological methods examined, the new Dimension for CyA determination can be relied on to produce results comparable to HPLC; other advantages are its simplicity, practicability and ease of handling.