Search results for "Flow Injection Analysis"
showing 10 items of 73 documents
Lysine synthesis control in Corynebacterium glutamicum RC 115 in mixed substrate (glucose-acetate) medium.
2003
The effect of acetate as a glucose co-substrate on growth, lysine synthesis and experimental lysine yield from carbon substrates by Corynebacterium glutamicum RC 115 was investigated. It was found that low amounts of acetate, injected with a glucose-acetate pulse into the steady-state continuous culture in bioreactor, caused a slight decrease in the specific rates of glucose uptake and bacterial growth, but a significant increase in the cell specific rate of lysine synthesis and an increase in lysine yield. In contrast, acetate injected in high amounts was followed by a drastic decrease in the values of these parameters. A strong increase in experimental lysine yield under the latter condit…
A new cell for the study of in situ chemical reactions using X-ray absorption spectroscopy
2005
An in situ cell for reductive and oxidative treatments at different temperatures that allows the possibility of recording data as a function of temperature has been designed and constructed for X-ray absorption experiments at the GILDA beamline BM08 of ESRF. The cell is linked to a mass quadrupole spectrometer providing control of the reaction gases and monitoring of the products. The apparatus allows measurements to be performed both in transmission and fluorescence geometry. The cell was tested by studying the CO oxidation reaction promoted by a Pt/ceria-zirconia-supported catalyst. The CO(2) yield is correlated with the structural results confirming the existence of a strong metal-suppor…
Sequential injection analysis (SIA)-chemiluminescence determination of indomethacin using tris[(2,2'-bipyridyl)]ruthenium(III) as reagent and its app…
2006
Abstract Automated sequential injection (SIA) method for chemiluminescence (CL) determination of nonsteroidal anti-inflammatory drug indomethacin ( I ) was devised. The CL radiation was emitted in the reaction of I (dissolved in aqueous 50% v/v ethanol) with intermediate reagent tris(2,2′-bipyridyl)ruthenium(III) (Ru(bipy) 3 3+ ) in the presence of acetate. The Ru(bipy) 3 3+ was generated on-line in the SIA system by the oxidation of 0.5 mM tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy) 3 2+ ) with Ce(IV) ammonium sulphate in diluted sulphuric acid. The optimum sequence, concentrations, and aspirated volumes of reactant zones were: 15 mM Ce(IV) in 50 mM sulphuric acid 41 μL, 0.5 mM Ru(bipy) 3 …
Flow-Injection Spectrophotometric Determination of Phenolic Drugs and Carbamate Pesticides by Coupling with Diazotized 2,4,6-Trimethylaniline
1999
Abstract A flow-injection (FI) spectrophotometric system is proposed for the determination of phenols and carbamates. In the FI manifolds, the solutions of phenols or carbamates (the latter after hydrolysis with NaOH) were injected into a diazonium ion carrier stream at pH 9.5 (buffered with tetrahydroborate), which was formed by mixing 2,4,6-trimethylaniline (TMA) with nitrate in a sodium dodecyl sulfate aqueous micellar medium. Absorbance was measured at 550 nm. The system combines the advantages derived from the use of TMA for the coupling of phenols in basic micellar media, because of the inhibition of the self-coupling reaction of the reagent, with the precision and speed of the FI pro…
Photo-induced chemiluminometric determination of Karbutilate in a continuous-flow Multicommutation assembly
2006
The present paper deals with the chemiluminescent determination of the herbicide Karbutilate on the basis of its previous photodegradation by using a low-pressure Hg lamp as UV source in a continuous-flow multicommutation assembly (a solenoid valves set). The pesticide solution was segmented by a solenoid valve and sequentially alternated with segments of the 0.001 mol l(-1) of NaOH solution, the suitable media for the formation of photo-fragments; then it passes through the photo-reactor and was lead to the flow-cell after being divided in small segments which were sequentially alternated with the oxidizing system; 2 x 10(-5) mol l(-1) of potassium permanganate in 0.2% pyrophosphoric acid.…
Flow injection Fourier transform infrared determination of nicotine in tobacco
2000
A fully automated procedure is proposed for the Fourier transform infrared (FTIR) determination of nicotine in tobacco. The method is based on the on-line extraction of nicotine with CHCl3. Samples, weighed inside empty extraction cartridges, were humidified with NH3 and the cartridges were installed in a flow manifold in which they were extracted with 2 ml CHCl3 for 2 min, then 400 microliters of the extract were introduced into a micro-flow cell using a carrier of CHCl3 and the IR spectrum was registered continuously. The absorbance, in the wavenumber range 1334-1300 cm-1, was measured, obtaining a peak as a function of time. The area of this peak was interpolated on a calibration line es…
Simultaneous dissolution profiles of two drugs, sulfadiazine-trimethoprim and amitriptyline-perphenazine, in solid oral dosage forms by a FIA manifol…
2002
The simultaneous determination of two dissolution profiles with the aid of a Flow Injection Analysis assembly has been applied to: (a) sulfadiazine-trimethoprim in tablets and (b) amitriptyline-perphenazine in sugar coated pills. The selected combinations are drugs which have overlapping UV-vis spectra. The officially proposed procedure from the pharmacopoeias has been adapted for the FIA methodology and derivative spectrophotometry and zero crossing. Preliminary experiments on the suitability of the simultaneous determination of both drugs were performed. The empirical profiles were adjusted by regression analysis using different approaches. The 3-parameter plot method was finally selected…
Determination of Phenylephrine Hydrochloride by Flow Injection Analysis with Chemiluminescence Detection
2001
Abstract A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80°C. The calibration graph is linear over the range 0.03–8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.
FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.
1994
Abstract The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0–75 μg ml −1 of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h −1 . The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.
Copper carbonate as a solid-bed reactor for spectrophotometric determination of doxycycline and oxytetracycline in an unsegmented continuous flow ass…
1993
The FIA-spectrophotometric determination of doxycycline was carried out by reaction of the drug with cupric ions entrapped in a polymeric material in a packed-bed reactor: the complex formed was then injected into a manifold with an alkaline solution as carrier. The developed colour was monitored at 395.0 nm. The method was applied to the determination of doxycycline in different pharmaceutical formulations. The calibration graph for doxycycline hyclate was linear over the range 10.0-80.0 mg ml-1 (n = 8) with a relative standard deviation of 1.4% (at 25 mg ml-1) and a sample throughput of 128 h-1. The proposed procedure was also applied to the determination of oxytetracycline in pharmaceuti…