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Flow-injection System (flow-injection + system)
Selected AbstractsNano-level detection of naltrexone hydrochloride in its pharmaceutical preparation at Au microelectrode in flowing solutions by fast fourier transforms continuous cyclic voltammetry as a novel detectorJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2007P. Norouzi Abstract An easy and fast Fourier transform continuous cyclic voltammetric technique for monitoring of ultra trace amounts of naltrexone in a flow-injection system has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some of advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The method was linear over the concentration range of 0.34,34000 pg/mL (r,=,0.9985) with a limit of detection 8.0,×,10,4 nM. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay naltrexone in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the naltrexone were considered. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:2009,2017, 2007 [source] Catalytic effect of ferricyanide between myoglobin and luminol and effect of temperatureLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2007Xin Gao Abstract Specific catalytic oxidation of oxymyoglobin (MbO2) and luminol by ferricyanide was studied in a flow-injection system. MbO2 in different redox states (ferric and ferrous) was oxidized to Mb(FeIII) by ferricyanide, and then specific binding of the ferrocyanide anion to Mb(FeIII) to the His 119 (GH1) region accelerated the electron transfer between Mb(FeIII) and luminol, which produced a chemiluminescence (CL) signal at 425 nm. The increased CL emission was correlated with the myoglobin concentration in the range 0.16,7.5 µg/mL. Thermogravimetry and differential scanning calorimetry were used to investigate the temperature effects on this reaction. The results showed that the CL intensity in the presence of myoglobin changed considerably with heating in the range 15,50°C, and the maximal CL intensity was observed at 40°C, corresponding to the glass transition temperature of myoglobin. The effect of different ligands and interferences were also studied. Copyright © 2006 John Wiley & Sons, Ltd. [source] Flow-injection,chemiluminescence method for the determination of penicillin G potassiumLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4-5 2005Wei Cao Abstract The degradation product of penicillin G potassium can react with potassium permanganate in acidic medium and produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow-injection system. The experiments indicated that under optimum conditions, the chemiluminescence intensity was linearly related to the concentration of penicillin G potassium within the range 1.0 × 10,7,1.0 × 10,5 g/mL, with a detection limit (3,) of 7 × 10,8 g/mL. The relative standard deviation was 1.0% for 4.0 × 10,7 g/mL penicillin G potassium solution (n = 11). This method has the advantages of simple operation, fast response and high sensitivity. The method was successfully applied to the analysis of penicillin G potassium in raw medicines. Copyright © 2005 John Wiley & Sons, Ltd. [source] Flow injection,chemiluminescence determination of amoxycillin using potassium permanganate and formaldehyde systemLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2005Wei Cao Abstract It was found that amoxycillin can react with potassium permanganate in an acidic medium to produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow-injection system. The experimental results indicate that, under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of amoxycillin in the range 5.48 × 10,8,2.74 × 10,6 mol[sol ]L, with a detection limit (3,) of 4.1 × 10,8 mol[sol ]L. The relative standard deviation was 1.0% at 1.1 × 10,6 mol[sol ]L amoxycillin (n = 11 measurements). This method has the advantages of high sensitivity, fast response and ease of operation. The method was successfully applied to the determination of amoxycillin in raw medicines and capsules. Copyright © 2005 John Wiley & Sons, Ltd. [source] Contactless Conductivity Detection in Capillary Electrophoresis: A ReviewELECTROANALYSIS, Issue 24 2004Pavel Kubá Abstract The popularity of contactless conductivity detection in capillary electrophoresis has been growing steadily over the last few years. Improvements have been made in the design of the detector in order to facilitate its handling, to allow easy incorporation into available instruments or to achieve higher sensitivity. The understanding of its fundamental working principles has been advanced and the detection approach has also been transferred to lab-on-chip devices. The range of applications has been extended greatly from the initial work on small inorganic ions to include organic species and biomolecules. Concurrent determination of cations and anions by dual injection from opposite ends has been demonstrated as well as sample introduction by using flow-injection systems for easy automation of the process. [source] A Lactulose Bienzyme Biosensor Based on Self-Assembled Monolayer Modified ElectrodesELECTROANALYSIS, Issue 17 2004Susana Campuzano Abstract A bienzyme biosensor in which the enzymes ,-galactosidase (,-Gal), fructose dehydrogenase (FDH), and the mediator tetrathiafulvalene (TTF) were coimmobilized by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer on a gold disk electrode, is reported. The working conditions selected were Eapp=+0.10,V and (25±1),°C. The useful lifetime of one single TTF-,-Gal-FDH-MPA-AuE was surprisingly long, 81,days. A linear calibration plot was obtained for lactulose over the 3.0×10,5,1.0×10,3,mol L,1 concentration range, with a limit of detection of 9.6×10,6,mol L,1. The effect of potential interferents (lactose, glucose, galactose, sucrose, and ascorbic acid) on the biosensor response was evaluated. The behavior of the SAM-based biosensor in flow-injection systems in connection with amperometric detection was tested. The analytical usefulness of the biosensor was evaluated by determining lactulose in a pharmaceutical preparation containing a high lactulose concentration, and in different types of milk. Finally, the analytical characteristics of the TTF-,-Gal-FDH-MPA-AuE are critically compared with those reported for other recent enzymatic determinations of lactulose. [source] | ||||||||||