Determination of metoprolol in human plasma by column switching high-performance liquid chromatography

Summary Retention characteristics of metoprolol have been studied in reversed phase mode on RP2, RP8 and CN columns. The plots of retention time as a function of the acetonitrile content and of the ionic strength of the mobile phase permitted the choice of the best conditions to separate metoprolol from plasma components by switching of these three types of columns.Human plasma (0.5–1 ml) diluted with water is first injected on a RP2 column (25–40 m particle diameter, prepared by dry packing) and rinsed with water. The sample is then back eluted with acetonitrile-0.022 M acetate buffer (7525, v:v) and switched to a CN column (10 cm long, 5 m particle diameter). The heart cut of the eluate is selected and loaded on a RP8 analytical column (25 cm long, 5 m particle diameter) with acetonitrile-0.088 M acetate buffer (7525, v:v) as mobile phase.Auto-sampler and switching valves are actuated automatically by a computing integrator based on a fixed time schedule. The duration of one cycle is about 30 min, but the last analytical step is about 15 min and represents the time interval between two injections. Metoprolol, its alpha-hydroxy metabolite and the internal standard are detected by fluorescence (_ex= 225 nm; _em > 320 nm).Presented at the 14th International Symposium on Chromatography London, September, 1982     

Simultaneous determination of lomefloxacin,fenbufen and felbinac in human plasma using high performance liquid chromatography

Summary A simple, specific, and sensitive high-performance liquid chromatography method has been developed for simultaneous determination of the lomefloxacin, febufen, and felbinac in human plasma. Plasma-spiked with internal standard, was vortex-mixed for 1 min with a mixture of dichloromethane-diethylether (80:20, v/v). The evaporated extract was dissolved in 0.02 M NaOH. The extracts were chromatographed on an Supelcosil LCSAX column (5 m 250×4.6 mm I.D.) equipped with a guard column with a mibile phase composed of acetonitrile and phosphate buffer, with ultraviolet detection. Drugs were resolved at ambient temperature on a flow rate was 1.2 mL min^–1, and monitoring was performed at 280 nm. The detection limits for lomefloxacin was 0.05 g mL^–1, 0.02 g mL^–1 for fenbufen and 0.03 g mL^–1 for felbinac. No interference from other commonly administered drugs or endogenous substances was observed. The method is fast since it involves two extraction steps followed by evaporation of organic solvent and chromatography of the residue. This method was found to be applicable to pharmacokinetic and pharmacodynamic studies of each drug after the concomitant administration of lomefloxacin and febufen.     

Liquid chromatographic separation of monoamino analogues of dideoxyadenosine and 9-(dideoxy-β-D-lyxo-pentofuranosyl)adenine from adenine

Summary A liquid chromatographic method that can separate each of the monoamino analogues of dideoxyadenosine and 9-(-dideoxy--D-lyxo-pentofuranosyl)adenine from their main degradation product, adenine, is described. The influence of the pH of the mobile phase, the type and concentration of the organic modifier and the concentration of the silanol masking agent and the buffer have been investigated. Several reversed phases were examined. Samples were finally analyzed on a 10 m Spherisorb ODS1 column (250 mm×4.6 mm I.D.) using acetonitrile –0.2 M potassium phosphate buffer pH 6.0–0.2 M tetramethylammonium phosphate pH 6.0-water (550.589.5, v/v) as the mobile phase. The interactions between the solute and the stationary phase are discussed in view of the basic properties of the compounds under study.     

Polarographische Bestimmung von ?thylen-bis-thiurammonosulfid

Zusammenfassung Das polarographische Verhalten von Äthylen-bis-thiurammonosulfid, das als fungitoxisches Abbauprodukt der Pflanzenschutzmittel Maneb, Zineb und Nabam auftritt, wird beschrieben. Zur Bestimmung wird M Acetatpuffer pH 4,7 als Grundlösung empfohlen. Es erscheint eine gut ausgebildete Reduktionsstufe mit dem Halbstufen potential –1,085 V (GKE). Die untere Bestimmungsgrenze liegt bei etwa 0,5 g/ml. Bei Anwendung der Impulsmethode (single-sweep-Technik) lassen sich in 0,8 N HCl noch 0,05 g/ml bestimmen.

---

Polarographic determination of ethylene-bis-thiuram-monosulphide

The polarographic properties of ethylene-bis thiuram-monosulphide, a fungitoxic degradation product of the fungicides Maneb, Zineb, and Nabani have been described. For analytical purposes the recommended supporting electrolyte is M acetate buffer (pH 4,7) in which a well-defined reduction wave is produced at a half wave potential of –1.085 V (SCE). The lower limit of detection is near 0.5 g/ml for classical DC-polarography whereas it is still possible to determine 0.05 g/ml 0.8 N HCl using the single sweep method.

     

Polarographische Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion

Zusammenfassung Eine polarographische Methode zur direkten Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion wird beschrieben. Als Grundelektrolyt wird Britton-Robinson-Puffer (pH 2,8) und Methanol (41v/v) empfohlen. Die untere Bestimmungsgrenze liegt bei 20 g Diazepam/ml Blut.

---

Polarographic determination of diazepam in cadaver blood without prior extraction

Summary A polarographic method is described for the direct determination of diazepam in cadaver blood without previous extraction. The fundamental electrolyte recommended is Britton-Robinson buffer solution (pH=2.8) and methanol (41v/v). The lower determination limit is situated at 20g diazepam/ml blood.

     

A HPLC method for the quantitation of propafenone and 5-hydroxy propafenone

Summary This paper presents a method for the simultaneous detection of propafenone and 5-hydroxypropafenone (5-OH propafenone) using HPLC. The method is sensitive, selective, and reproducible. The chromatographic separation is based on a 25×0.4 cm 5 m ODS column, a mobil phase of 0.1 M potassium phosphate (K₂HPO₄) buffer (pH 2.5) and acetonitrile (6337), and UV absorbance detection. There is excellent intra- and interassay variation. Retention times of the internal standard, propafenone, and 5-OH propafenone are 4.3, 6.0 and 2.9 minutes respectively. This method shows linearity over the therapeutic range for propafenone and 5-OH propafenone (0.15 to 3.0 g/ml and 0.075 to 1.5 g/ml respectively). No interference has been found from other commonly administered drugs, including several antiarrhythmic drugs, at therapeutic levels.     

Determination of traces of sodium alkylbenzenesulphonate by high-performance liquid chromatography. Application to water

Summary For the trace determination of sodium alkylbenzenesulphonate (ABS) by HPLC the following conditions were employed: Shimadzu ZORBAX SIL Column (5 m, 4.6 mm i.d. x 150 mm) as stationary phase, 0.2% ammoniaethanol (v/v) as mobile phase, UV detector at 225 nm, injection volume 12 l. The chromatograms of ABS were simple and sharp (detection limit of ABS 0.02 g in 12 l of ethanol). The calibration curves of ABS were linear in a concentration range of 0.03 0.3 g in 12 l of ethanol. In the case of linear sodium dodecylbenzenesulphonate positive errors of 1 4% were caused by non-ionic surfactants or laurylsulphate (6 times excess), 10 50% positive errors were caused by 2 6 times excess of household detergents.Standard water samples containing ABS were treated with a weak base anion-exchange resin, the adsorbed ABS were eluted, and then determined either by HPLC or by the methylene blue spectrophotometric method. Recoveries of ABS in water were about 92 107% by HPLC.

---

Bestimmung von Spuren Natriumalkylbenzolsulfonat mit Hilfe der HPLC. Anwendung auf Wasser

Zusammenfassung Für die Spurenbestimmung von Natriumalkylbenzolsulfonat (ABS) durch HPLC werden die folgenden Bedingungen empfohlen:Shimadzu ZORBAX SIL (5 m, 4,6 mm x 150 mm) als stationäre Phase, 0,2% Ammoniak/Ethanol als mobile Phase, UV-Detektor bei 225 nm, Injektionsvolumen 12 l. Die erhaltenen Chromatogramme sind einfach und scharf (Nachweisgrenze 0,02 g in 12 ml Ethanol). Die Eichkurven sind im Konzentrationsbereich von 0,03–0,3 g in 12 l Ethanol linear. Im Falle des linearen Natriumdodecylbenzolsulfonats werden bei Anwesenheit von nicht-ionischen oberflächenaktiven Substanzen oder von Laurylsulfat in 6fachem Überschuß positiver Fehler von 1–4% erhalten; bei 2–6fachem Überschuß von Haushaltswaschmitteln ergeben sich positive Fehler von 10–50%.Standard-Wasserproben werden zunächst einer Behandlung mit einem Anionenaustauscher unterzogen, die adsorbierten ABS eluiert und durch HPLC oder nach der Methylenblaumethode analysiert. Wiederfindungsraten liegen bei 92–107%.

     

Synthesis,characterization and crystal structures of heterometallic trinuclear carbonyl sulfido clusters (η5-Cp)MoFeCo- (CO)8(μ3-S) and [(η5-Cp)Mo]2Fe(CO)7(μ3-S)

HFe2Co(CO)9(3-S) reacts with (5-Cp)Mo(CO)3Cl in refluxing THF to give heterometallic trinuclear clusters (5-Cp)MoFeCo(CO)8(3-S) and [(5-Cp)Mo]2Fe(CO)7-(3-S), which have been characterized by elemental analyses, i.r., 1H- and 13C-n.m.r. and X-ray crystal structure determination. An electrophilic addition–elimination sequence is proposed for their formation.     

A study of the thermal decompositions of orthotelluric acid,urea and the orthotelluric acid adduct with urea

A new type of deposit has been observed on the inside inner surface at glass exhibition cases for textiles. By thermogravimetric methods the main part of the coating has been shown to consist of wool fibers. The origin is the textile itself, and the fibers have been transported due to an electrostatic charge induced by polishing from the outside. Such damage can be avoided by grounding the boxes.

---

Zusammenfassung Ein neuer Typ von Ablagerungen an der Innenseite von Ausstellungsvitrinen für Textilien wurde beobachtet. Durch thermogravimetrische Methoden konnte gezeigt werden, dass der Hauptteil der Ablagerung aus Wollfasern besteht. Diese stammen von den Textilien selbst und gelangen infolge der durch Polieren der Aussenseite induzierten elektrostatischen Ladung an die Scheiben. Solche Schäden können durch Erdung der Vitrinen vermieden werden.

---

. , . , , . .

     

Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins

Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL^–1 for bovine serum albumin (BSA), 0.01–6.0 g mL^–1 for human serum albumin (HSA), 0.05–8.0 g mL^–1 for -globulin (-G), and 0.04–4.0 g mL^–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL^–1 BSA, 1.90% for 1.0 g mL^–1 HSA, 1.65% for 1.0 g mL^–1 -G, and 2.32% for 1.0 g mL^–1 ovalbumin.     

Elements in car and truck tires and their volatilization upon incineration

The trace metal loading of used car and truck tires and the fractions of the metals volatilized upon incineration of the tire were determined. INAA was chosen due to its multielement analysis capability and its low detection limit for many elements. A high purity planar germanium detector was used. Among the elements measured were, Al (4–150 g/g), Ti (41–730 g/g), V (0.04–0.4g/g), Mg (>80–580 g/g), Zn (1–2.2%) as typical concentrations; also some amounts of antimony, bromine and arsenic have been found. Major differences in elemental concentrations have been observed between the tread and the wall of a tire, and also between different brands.     

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.     

Analysis of reduced glutathione using a reaction with 2,4′-dichloro-1-(naphthyl-4-ethoxy)-s-triazine (EDTN)

A fluorescent adduct was formed between 2,4-dichloro-l-(naphthyl-4-ethoxy)-s-triazine (EDTN) and reduced glutathione in a reaction at 37 °C and pH 9.2. This reaction was used as the basis of an assay for reduced glutathione. The fluorescence was examined at an excitation wavelength of 319 nm and an emission wavelength of 425 nm after extraction of residual unreacted EDTN with methylene dichloride and subsequent dilution of the aqueous phase with ethanol containing 0.01 percent Triton X-100. The reaction rate was low at pH 7 but was accelerated by addition of preparations containing the enzyme glutathione-S-transferase. The adduct gave a discrete peak using isocratic elution with HPLC on a Nova-pak C₁₈ 3 m reverse phase column and a solvent system of methanol: 0.1 M phosphate buffer pH 6.3 (4060). An analytical concentration range of 24 to 240 M reduced glutathione was obtained with an ultraviolet detection system but the concentration range was 7.5 to 75 M when a fluorescence detection system was used. Adducts of other mercapturic acid pathway thiol compounds were not formed at 37 °C under the conditions used and hence did not interfere in the assay. They were formed by heating EDTN and the respective thiol compound at 60 °C for 30 min and they clearly separated from the reduced glutathione compound on HPLC analysis. A strong reaction was observed with digitonin while solutions of tyrosine, at 10 mM concentration, also reacted but these reactants are unlikely to interfere with reduced glutathione analysis in biological systems. When adduct formation was used to estimate reduced glutathione concentrations in some mammalian and plant tissues the reaction using 2,4-dichloro-l-(naphthyl-4-ethoxy)-s-triazine and HPLC separation gave the same results as ano-phthaldialdehyde assay for liver and muscle but the HPLC method gave slightly lower values for other mammalian and plant tissues. The differences were attributed to other material in the tissue extracts which was fluorescing at the same wavelengths as the reduced glutathione adduct.     

Reaction scheme in the non-isothermal decomposition of (C6H5NH3)4Mo8O26 · 2 H2O

The thermogravimetric decomposition of anilinum octamolybdate has been studied under non-isothermal conditions to elucidate the chemical reactions taking place in the first step of decomposition of the anhydrous compound.The decomposition products were analyzed by gas-liquid chromatography, gas chromatography-mass spectrometry (GC/MS), infrared spectroscopy and X-ray powder diffraction.The main decomposition product of aniline turned out to be indole, which is different from the major product in the isothermal decomposition at the same temperature, i.e. N-ethyl-aniline.A dehydrocyclization reaction is suggested as the rate-dependent process. This is probably due to the catalytic effect of the octamolybdate anion.

---

Zusammenfassung Die thermische Zersetzung von Anilinoctamolybdat wurde unter nicht-isothermen Bedingungen thermogravimetrisch untersucht, um die im ersten Zersetzungsschritt der wasserfreien Verbindung verlaufenden chemischen Reaktionen aufzuklären. Die Zersetzungsprodukte wurden mittels Gas-Flüssigkeits-Chromatographie, Gaschromatographie-Massenspektrometrie (GC/MS), Infrarotspektroskopie und Röntgendiffraktometrie analysiert. Als Hauptprodukt der Zersetzung von Anilin wurde Indol gefunden, während bei isothermer Zersetzung bei gleicher Temperatur vorwiegend N-Äthylanilin entsteht. Es wird angenommen, daß beim nicht-isothermen Prozeß eine wahrscheinlich durch das Octamolybdat katalysierte Dehydrocyclisierungsreaktion verläuft.

---

, . - , -- , . , -N- . , , -.

     

Production of96Tc and95mTc via the93Nb(α, xn) Reactions

Relatively longer liver technetium tracers such as^95mTc (61 d) are useful for the development, evaluation and comparison of new technetium complexes for eventual development of^99mTc radiopharmaceuticals. The feasibility of producing⁹⁶Tc (4.35 d) and^95mTc (61 d) was studied by the alpha bombardment of pure Nb targets (⁹³Nb-100%).⁹⁶Tc was obtained in a yield of 30 Ci/Ah using 16 MeV alphas, but it contained significant activity of⁹⁵Tc (20 h) Relatively pure⁹⁶Tc and^95mTc was produced in yields of 18 Ci/Ah and about 1 Ci/Ah respectively with alphas of suitable energy and after allowing for suitable cooling periods after the end of bombardment (EOB).     

Direction of the action of glycosidases fromLimnaea stagnalis on the carbohydrate groups of the (Fc)5 region of immunoglobulins M

The action of the combined glycosidases fromL. stagnalis on the carbohydrate groups of two monoclonal immunoglobins M (Waldenström's disease) — IgM_El (I) and IgM_Ser (II) — has been studied by the semiquantitative evaluation of densitograms of glycopeptides after their separation by disc electrophoresis in polyacrylamide gel. The accessibility of the oligosaccharide groups (OGs) to the action of the glycosidases according to the positions of the OGs in a particular domain of the (Fc)₅ region of a IgM decreases for (I) in the sequence C3 C4 > hinge, and for (II) in the sequence hinge > C4 > C3. The difference in the accessibilities of the OGs (I) and (II) is apparently explained by differences in the conformations of (I) and (II). A hypothesis has been put forward concerning the possibility of the partial degradation of (II) by the accompanying proteases.N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 371–375, May–June, 1984.     

Speciation of Cr(III) and Cr(VI) by reversed phase high-performance liquid chromatography using UV-detection

Summary A method for the simultaneous determination of Cr(III) and Cr(VI) in water samples is described. The different reaction products of Cr(III) and Cr(VI) species with ammonium pyrrolidinedithiocarbamate (APDC) are extracted with ethyl acetate and determined by reversed phase HPLC using UV-detection. The procedure is optimized and its detection limit accordingly improved as compared to literature data. The detection limits achieved are 2.4 g/l for Cr(III) and 2.1 g/l for Cr(VI) and the calibration curves are linear between 5 g/l and 5000 g/l. For the speciation of Cr, APDC was demonstrated to be more suitable as chelating agent than sodium diethyldithiocarbamate (NaDDC). The procedure was applied to the determination of both Cr species in galvanic waste waters and its accuracy was approved by comparing the results (at the 100 g/l level) with those of a photometric determination of Cr(VI) species.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Determination of thiopental in human serum and plasma by reversed-phase high-performance liquid chromatography

Summary A high-performance liquid chromatographic method for the analysis of thiopental in 100l of human serum or plasma is described. The procedure involves protein precipitation with acetonitrile. The supernatant is directly injected into a chromatograph containing a reversed-phase CLC-ODS (Shimadzu) column. A 5050 (v/v) mixture of water-acetonitrile, at a flow-rate of 1.0ml/min is used as the mobile phase. Detection is carried out ata wavelength of 280nm. Total analysis time per sample is 10min. The assay was found to be linear in the range of 0.1 to 120g/ml. Reproducibility was good, with intra-assay coefficients of variation from 1.780 to 3.208% and inter-assay coefficients of variation from 3.241 to 4.860%. The absolute recoveries were 97.4 to 101,4%. Other drugs were tested for potential interference with the assay, but none was found.