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.     

Simultaneous Determination of Four Active Components in a Compound Formulation by Liquid Chromatography

Summary A rapid and accurate LC method is described for simultaneous determination of pseudoephedrine hydrochloride (PSE), acetaminophen (AMP), dextromethorphen hydrobromide (DEX), and diphenhydramine hydrochloride (DPH) in a compound formulation. Chromatographic separation of the four drugs was achieved on a Hypersil CN column (150 mm × 4.6 mm, 5 m particle) by use of a mobile phase comprising a mixture of 3 mM ion-pairing solution, 2% aqueous triethylamine solution, and 2 M phosphoric acid, 68:48:88 (v/v), pH 3.0, delivered at 1.0 mL min^–1. Compounds were detected at 215 nm and the run time was less than 10 min. The linearity, accuracy, and precision of the method were found to be acceptable over the concentration ranges 6.1–36.4 g mL^–1 for PSE, 65.0–390.0 g mL^–1 for AMP, 3.1–18.6 g mL^–1 for DEX, and 5.0–30.0 g mL^–1 for DPH.     

Synthesis and Molecular and Crystal Structure of K4.5{[Mo3(μ3-Te)(μ2-Te2)3(CN)6]I}I1.5·3H2O and Cs3{[Mo3(μ3-Te)(μ2-Te2)3(CN)6]I}·2H2O

Crystal structures of two new compounds containing trigonal tellurium-bridged cluster fragments [Mo₃(₃-Te)(₂-Te₂)₃]⁴⁺ were investigated. Crystal data for K_4.5{[Mo₃(₃-Te)(₂-Te₂)₃(CN)₆]I}I_1.5·3H₂O: space group , Z = 4, a = 13.280(1), c = 23.800(3) , V = 3635.0(6) ³, d _calc = 3.432 g/cm³, R ₁ = 0.0335, wR2 = 0.0912 for 1378 I _hkl > 2 _I from 3545 measured I _hkl ; for Cs₃{[Mo₃(₃-Te)(₂-Te₂)₃(CN)₆]I}·2H₂O: space group P2 ₁ /n, Z = 2, a= 9.650(2) , b = 22.297(5), c = 27.446(7) , = 94.10(2)°, V = 5890(2) ³, d _calc = 4.273 g/cm ³, R ₁ = 0.0384, wR ₂ = 0.0744 for 957 I _hkl > 2 _I from 3758 measured I _hkl (Enraf-Nonius CAD-4 diffractometer, MoK , graphite monochromator). In both compounds, ionic pairs {[Mo₃Te₇(CN)₆]I}^3– with Te_ax...I^– distances of 3.358-3.676 are formed. In the potassium salt, the {[Mo₃Te₇(CN)₆]I}^3– anion pairs are linked by the additional Te_eqI^– short contacts of 3.460 into two-dimensional corrugated layers perpendicular to the c axis of the unit cell. The structure of the cesium salt is ionic with interstitial H₂O molecules and double-layer closest packing of anions.     

Radiolysis of nitrous oxide adsorbed on alumina ionic mechanism of radiolysis of nitrous oxide on alumina with small surface areas

A mechanism is proposed for the radiolysis of adsorbed N₂O describing the experimental dependences of the radiation-chemical yields of O _st ^– and N₂ on N₂O coverages.

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N₂O, - O _st ^– N₂ N₂O.

     

Development and validation of a novel HPLC/ELSD method for the direct determination of tobramycin in pharmaceuticals,plasma, and urine

A novel method for the direct determination of the aminoglycoside tobramycin was developed and validated based on reversed-phase high-performance liquid chromatography (RP-HPLC) with evaporative light scattering detector (ELSD). Using a Waters ODS-2 C18 Spherisorb column with an evaporation temperature of 45°C and nitrogen pressure of 3.5 bar, the selected mobile phase consisted of water/acetonitrile 55:45 containing 1.5 mL L^–1 HFBA (11.6 mM) in an isocratic mode at a rate of 1.0 mL min^–1. Tobramycins retention time was 4.3 min with an asymmetry factor of 1.7. A logarithmic calibration curve was obtained from 1 to 38 g mL^–1 (r > 0.9998). LOD was 0.3 g mL^–1; within-day %RSD was 1.0 (n = 3, 4.7 g mL^–1) and between-day %RSD was 1.1 (3 days within a week). The developed method was applied to the determination of tobramycin in a pharmaceutical crude substance and formulations (eye drops and ointments). Dilution experiments revealed the absence of interference from excipients (no constant and proportional errors); recovery from spiked samples was 99–103% with %RSD < 2.2 (n = 3×3). The developed HPLC/ELSD method was also found to be applicable in the determination of tobramycin in human plasma (0.6–12.5 g mL^–1) and urine (1.5–12.5 g mL^–1) after solid-phase extraction using carboxylate cartridges followed by solvent evaporation (×2 preconcentration). A mean recovery of 86% for plasma and 91% for urine was obtained.     

Simultaneous Determination of Pioglitazone and Glimepiride by High-Performance Liquid Chromatography

A rapid and accurate HPLC method has been developed for simultaneous determination of pioglitazone and glimepiride. Chromatographic separation of the two pharmaceuticals was performed on a Cosmosil C₁₈ column (150 mm × 4.6 mm, 5 m) with a 45:35:20 (v/v) mixture of 0.01 m triammonium citrate (pH adjusted to 6.95 with orthophosphoric acid), acetonitrile, and methanol as mobile phase, at a flow rate of 1.0 mL min^–1, and detection at 228 nm. Separation was complete in less than 10 min. The method was validated for linearity, accuracy, precision, limit of quantitation, and robustness [1, 2]. Linearity, accuracy, and precision were found to be acceptable over the ranges 2.50–30.00 g mL^–1 for pioglitazone and 0.10–10.00 g mL^–1 for glimepiride.     

Characterization of airborne particulates by laser microprobe mass analysis

Summary Laser microprobe mass analysis (LAMMA) was applied to characterize aerosol particles collected and separated from 16m to 0.06m by a low pressure cascade impactor. Positive ion LAMMA spectra showed characteristic molecular peaks such as PbCl⁺, a series of Si₂O⁺–Si₂O₄ ⁺ and NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, and TiO⁺ in 0.06–0.12m, 0.5–1m and 4–8m fraction, respectively. In the negative ion LAMMA spectra, it was observed that the fragment peaks of sulfate ions were deficient above 2m and those of nitrate ions were deficient under 2m. LAMMA allows remarkable insights into the chemical nature of aerosol particles.

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Charakterisierung luftgetragener Teilchen durch Laser-Microprobe-Massenspektrometrie

Zusammenfassung Laser-Microprobe-Spektrometrie (LAMMS) wurde zur Analyse atmosphärischen Aerosols herangezogen, welches im Korngrößenbereich zwischen 16m und 0.06m mit einem Niederdruckkaskadenimpaktor fraktioniert gesammelt wurde. Positive LAMMS-Spektren zeigten charakteristische molekulare Peaks, wie etwa PbCl⁺, eine Serie von Si₂O⁺–Si₂O₄ ⁺ und NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, sowie TiO⁺ in der 0,06–0,12-m,- 0,5–1–m- bzw. 4–8-m-Fraktion. In den negativen LAMMS-Spektren konnten über 2m keine Fragmentpeaks für Sulfationen, unter 2m. keine für Nitrationen beobachtet werden. LAMMS ermöglicht eine bemerkenswerte Einsicht in die chemische Natur von Aerosolteilchen.

     

Katalytischer Nachweis und Bestimmung von Jodspuren mit Hilfe der 3,3′-Dimethylnaphthidin-Hydrogenperoxid-Reaktion

Zusammenfassung Die 3,3-Dimethylnaphthidin-Wasserstoffperoxid-Redoxreaktion wird von Jodid sehr stark katalysiert. Damit kann man bei Anwesenheit von Ameisensäure Jodid selbst in einer Grenzkonzentration von 0,002g/ml nachweisen bzw bestimmen. Dazu eignet sich die Simultankomparationsmethode. Im Konzentrationsbereich von 0,1 bis 0,01g J^–/5 ml beträgt der relative Fehler 3%. Ag⁺, Hg²⁺ oder Bi³⁺ dürfen nicht anwesend sein; andere störende Ionen können mit ÄDTA bzw. Weinsäure maskiert werden.

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Catalytic detection and determination of traces of iodine by means of the 3,3-dimethylnaphthidine-hydragen peroxide reaction

Summary The 3,3-dimethylnaphthidine-hydrogen peroxide redox reaction is strongly catalysed by iodide. Therefore, if formic acid is present, iodide itself may be detected or determined in a limiting concentration of 0.002g/ml. The simultaneous comparation method is appropriate here. In the concentration region from 0.1 to 0.01g I^–/5 ml, the relative error is 3%. Ag⁺, Hg²⁺ or Bi³⁺ may not be present. Other interfering ions can be masked with EDTA or tartaric acid.

     

Crystallization Behavior of Alkoxy-Derived Cordierite Gels

Alkoxy-derived cordierite gels were synthesized from tetraethylorthosilicate (TEOS), aluminum isopropoxide (Al(OPr ⁱ )₃), and magnesium ethoxide (Mg(OEt)₂). TEOS was partially hydrolyzed at molar ratios H₂O/TEOS = 1.2, in the presence of hydrochloric acid as a catalyst, HCl/TEOS = 0.1. Aluminum and magnesium alkoxides were added successively or as a double alkoxide. Phase transformations occurring in the gel were studied by differential thermal analysis, x-ray diffractometry, and Fourier-transform infrared spectroscopy. In all cases, -cordierite crystallized at similar temperatures (950–1000°C) with small amounts of spinel, which confirms dominant influence of the optimal conditions for partial hydrolysis of TEOS on the gels homogeneity. The transformation of - into -cordierite began at about 1100°C. Broadening of diffraction peaks and appearance of new bands in the FT IR spectra confirmed the transformation of - into modulated -cordierite at temperatures above 1300°C. Differential thermal analysis under nonisothermal conditions also proved homogeneous nucleation with constant rate and three-dimensional crystallite growth during -cordierite crystallization. The overall activation energy of the crystallization of -cordierite is 580 ± 81 kJ/mol.     

New cobalt trimethylacetate complexes with pyridine

The reaction of the tetranuclear trimethylacetate complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ with pyridine in acetonitrile was studied. Two new compounds, viz., the hexanuclear cobalt(ii) complex Co₆py₄(₃-OH)₂(-OOCCMe₃)₁₀ (25% yield) and the unusual ionic compound [Co₃py₃(₃-O)(-OOCCMe₃)₆]⁺[Co₄py(₄-O)(-OOCCMe₃)₇]^– (5% yield), were prepared. The structures of the new compounds were established by X-ray diffraction analysis.     

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).     

Determination of Dextromethorphan and Dextrorphan in Human Urine by High Performance Liquid Chromatography for Pharmacogenetic Investigations

The aim of the present study was to develop a sensitive method to measure dextromethorphan and dextrorphan in urine by HPLC to support pharmacogenetic studies in ethnic groups. Linearity was assessed in the range: 0.015–10 g mL^–1 for dextromethorphan and 1-10 g mL^–1 for dextrorphan. Inter and intra-day coefficients of variation were < 10%. Limits of detection and quantitation were 0.003 g mL^–1 and 0.015 g mL^–1 for dextromethorphan and 0.24 g mL^–1 and 1.0 g mL^–1 for dextrorphan, respectively. The method is reliable in helping determine the phenotype of Mexican ethnic groups using model drugs such as dextromethorphan.     

Separation of linear gramicidins using carbon dioxide-containing mobile phases

Packed-column supercritical-fluid chromatography (pSFC) is presented as a novel method for separating and analyzing gramicidin samples. By use of methanol-modified carbon dioxide as a mobile phase the pentadecapeptides gramicidin A (gA), gramicidin B (gB), and gramicidin C (gC) are readily separated and eluted from a PRP-1 poly(styrene–divinylbenzene) column. Although optimum separation conditions are typically achieved near a column temperature of 40°C, a column pressure of 11 MPa, and 30% methanol modifier, pressure and modifier gradients around these values are also found to improve the overall separation time. Measurements indicate that the mobile phase solubility of gramicidin under these conditions is 5.0±0.4 g mL^–1. Collection of individual peaks during chromatography achieved analytical-scale isolation of 2 g refined gC from 20 g injected gramicidin D. Further, supercritical-fluid extraction of 200 g gramicidin D from a Chromosorb 102 support packed into the vessel produced 57 g gA in 90% purity. The results establish that carbon dioxide-based mobile phases can be successfully used for the separation of individual gramicidin species.     

Determination of Levodopa and Benserazide Hydrochloride in Pharmaceutical Formulations by CZE with Amperometric Detection

A novel method, capillary electrophoresis with amperometric detection, has been established for rapid and effective measurement of levodopa (L-dopa), and benserazide (BS) and its impurity (R,S)-2-amino-3-hydroxypropanohydrazide (Ro-04-1419) in co-beneldopa pharmaceutical formulations. Suitable separation and amperometric detection conditions were investigated and optimized. The optimum conditions of CZE detection were 40 mm phosphate solution at pH 5.3 as running buffer, 17 kV separation voltage, carbon-disk working electrode, 0.95 V (relative to Ag/AgCl) as detection potential, and sample injection for 8 s at 17 kV. The linear ranges were from 1.25 to 50 g mL^–1 for L-dopa, 1.2 × 10^–1 to 25.5 g mL^–1 for BS, and 1.0 × 10^–2 to 4.4 × 10^–1 g mL^–1 for Ro-04-1419, with correlation coefficients of 0.9994, 0.9951, and 0.9933, respectively. The detection limits for L-dopa, BS, and Ro-04-1419 were 0.38, 0.02, and 0.004 g mL^–1, respectively. Average recoveries were 100.2% for L-dopa, 102.4% for BS, and 90.8% for Ro-04-1419. This method was successfully applied to co-beneldopa granules and tablets.Revised: 30 November and 22 December 2004     

Nuclear interferences of uranium and thorium in a reactor neutron activation analysis determination of cerium using the radionuclides141Ce and143Ce

The interference contributions of uranium and thorium to the determination of cerium based on radionuclides¹⁴¹Ce and¹⁴³Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for¹⁴¹Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10^–3 g Ce/g Th, and for¹⁴³Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10^–3 g Ce/g Th.     

Synthesis and Structure of the Complex [Mo3(μ3-S)(μ2-S2)3(Et2NCS2)3 +Br-

Tri-₂-disulfido-₃-thiotris(diethyldithiocarbamato)-S,S'-triangle-trimolybdenum bromide [Mo₃(₃-S)(₂-S₂)₃(Et₂NCS₂)₃ ⁺Br^- was obtained and characterized.     

Capacitive chemical sensor for fenvalerate assay based on electropolymerized molecularly imprinted polymer as the sensitive layer

A capacitive chemical sensor for fenvalerate is reported. By using ac impedance measurements the sensor has been based on the decrease in capacitance caused by the analyte used as the template in the formulation of an electropolymerized molecularly imprinted polymer as receptor layer. Improvement of the insulating properties of the sensor was investigated in detail. The capacitive sensor was prepared by a deposition of a self-assembled monolayer of 2-mercaptobenzimidazole (2-MBI) before electropolymerization of 2-MBI and subsequent treatment with n-dodecanethiol to eliminate pinholes and defects in the polymerized 2-MBI film. From the calibration curve concentrations of fenvalerate up to 9 g mL^–1 could be detected with a linear determination range up to 5 g mL^–1 and a detection limit of 0.36 g mL^–1. No significant interference was observed from common pyrethroid insecticides.     

Fällungsanalyse im Mikrogrammbereich: Eine neue Methode

Zusammenfassung Eine neue Methode zur Durchführung gravimetrischer Bestimmungen im Mikrogrammbereich wurde beschrieben; diese beruht im wesentlichen darauf, daß der Niederschlag nicht mehr zusammen mit dem Filter, sondern nach Überführen mit einem geeigneten Lösungsmittel in einem separaten Wägegefäß gewogen wird.Die dazu nötigen Geräte und deren Herstellung wurden beschrieben. Nach dieser Methode wurden folgende Bestimmungen mit zufriedenstellender Richtigkeit durchgeführt: 2,5–25g Al, 5–50g Cu und 5–50g Zn mit Oxin, 2,5–25g Fe(III) und 2,5–25g Ti(IV) mit N-Benzoyl-phenylhydroxylamin, 5–50g Ni und 5–50g Cu mit Salicylaldoxim, 2,5–50g Co(II) und 2,5–50g Fe(III) mit -Nitroso--naphthol sowie 5–50g Chlorid als Silberchlorid.

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Precipitation analysis in the microgram-scale: A new method

Summary A new method for gravimetric determinations in the microgram-scale is described. This method is based on the fact that the precipitate is not weighed together with the filter but is transferred to a separate weighingvessel using a suitable solvent. The necessary simple devices and their use are described. The following determinations were carried out with satisfying accuracy: 2,5–25g Al, 5–50g Cu and 5–50g Zn with Oxine, 2,5–25g Fe and 2,5–25g Ti withN-benzoylphenylhydroxylamine, 5–50g Ni and 5–50g Cu with salicylaldoxime, 2,52–50g Co and 2,5–50g Fe with -nitroso--naphthol and 5–50g chloride as silver chloride.

     

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.