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At least 289 records · Page 16Linked to original sources
PubMed2003

Simple and selective method for determination of iodide in pharmaceutical products by flow injection analysis using the iodine-starch reaction.

This work exploited the well-known iodine-starch reaction for development of a simple flow-injection (FI) method for determination of iodide in pharmaceutical samples. Iodide in an injected zone was oxidized to iodine. A gas diffusion unit enables selective permeation of iodine through a hydrophobic membrane. Detection was made very selective for elemental iodine by employing formation of the I(3)(-)-starch complex. The detection limit (3 S/ N) of the system was 1 mg I L(-1). For a liquid patent medicine used for asthma treatment we suggested modification of the system. Direct injection of this sample, which contains a particularly high concentration level of iodide (ca. 9000 mg I L(-1)), can be achieved by coupling a dialysis unit to the FI system. This has increased the working range to 6000-10,000 mg I L(-1) without employing complicated nanoliter injection.

Flow Injection Analysis↗
PubMedDate not supplied

Flow-injection analysis of cobalt(II) utilizing enhanced lophine chemiluminescence with hydroxylammonium chloride.

A rapid and convenient flow-injection method is described for the determination of Co(II). The method utilized the phenomenon that the lophine-Co(II)-H2O2 chemiluminescence (CL) reaction is enhanced in alkaline media by the addition of hydroxylammonium chloride. The calibration curve was linear over the range 2 x 10(-7) to 2 x 10(-5) M with a detection limit of 4.5 x 10(-8) M (0.9 pmol) at a signal-to-noise ratio of 2. The method was applied to the assay of cyanocobalamin in commercially available eye lotions.

Chromatography, Liquid↗
PubMed1994

Application of automated flow injection analysis to determine nitrite and nitrate in mouse brain.

Nitric oxide level in the mouse brain was estimated by determination of nitrite and nitrate using an automated flow injection analyser for NOx. Different experimental conditions were examined to determine which produced reproducible results. After pretreatment of tissue specimens by the ZnSO4-NaOH method for deproteinization, reproducible and constant values were obtained. The values were more accurate immediately after sectioning without freezing than after 24 h with freezing. Two sacrifice methods, decapitation and microwave irradiation of the head, were investigated, but there was no significant difference between the two. No substances in the mouse brain exerted a positive or negative influence on the results. These results show that our method is indeed applicable to the brain tissue.

Animals↗
PubMed1990

Simultaneous determination of glucose, ethanol and lactate in alcoholic beverages and serum by amperometric flow injection analysis with immobilized enzyme reactors.

Glucose, ethanol and lactate were determined simultaneously in a flow injection system by using a parallel configuration of immobilized enzyme reactors. Hydrogen peroxide produced was monitored amperometrically at the potential of +0.65 V vs. Ag/AgCl. Linear relations between sensor responses and each species were observed in the ranges of 0.02-10 mM (glucose), 5 x 10(-4)-0.1% (v/v) (ethanol) and 0.005-1 mM (lactate) with correlation coefficients larger than 0.999 for each species. The relative standard deviations for 10 successive injections were 1.4, 0.5 and 1.1% for glucose (1 mM), ethanol (5 x 10(-3)% (v/v] and lactate (0.05 mM), respectively. Analysis of serum samples was performed with urate-eliminating reactors which were set just before each immobilized enzyme reactor. Interference of ascorbate in a serum sample was completely eliminated by using an ascorbate-eliminating reactor which was set before the sample injection valve. Application of the system to alcoholic beverages and control serum was described and the results were compared with those of free enzymatic, spectrophotometric analysis (F-kit or C-test method).

Alcoholic Beverages↗
PubMed2004

Determination of choline in milk, milk powder, and soy lecithin hydrolysates by flow injection analysis and amperometric detection with a choline oxidase based biosensor.

A fast-response and interference-free amperometric biosensor based on choline oxidase immobilized onto an electropolymerized polypyrrole film for flow injection determination of choline in milk, milk powder, and soy lecithin hydrolysates is described. The sensor displayed an Imax value of 1.9 +/- 0.2 microA and an apparent Michaelis-Menten constant, k'M, equal to 1.75 +/- 0.07 mM. Detection limits of 0.12 microM could be obtained. Because even a slight deterioration of the anti-interference membrane can adversely affect measurement accuracy, a real time monitoring of the biosensor selectivity has been achieved by a dual Pt electrode flow-through cell where the enzyme modified electrode is coupled to an enzyme-free electrode in a parallel configuration. Finally, bracketing technique (alternate injections of sample and standards) allows a two-point calibration to be performed in real-time, correcting for any drift in sensor response.

Alcohol Oxidoreductases↗
PubMed2003

Miniaturized tris(2,2'-bipyridyl)ruthenium(II) electrochemiluminescence detection cell for capillary electrophoresis and flow injection analysis.

The design and performance of a miniaturized chip-type tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)] electrochemiluminescence (ECL) detection cell suitable for both capillary electrophoresis (CE) and flow injection (FI) analysis are described. The cell was fabricated from two pieces of glass (20 x 15 x 1.7 mm), and the 0.5-mm-diameter platinum disk was used as working electrode held at +1.15 V (vs silver wire quasi-reference), the stainless steel guide tubing as counter electrode, and the silver wire as quasi-reference electrode. The performance traits of the cell in both CE and FI modes were evaluated using tripropylamine, proline, and oxalate and compared favorably to those reported for CE and FI detection cells. The advantages of versatility, sensitivity, and accuracy make the device attractive for the routine analysis of amine-containing species or oxalate by CE and FI with Ru(bpy)3(2+) ECL detection.

Journal Article↗
PubMed2000

A factorial design for optimizing a flow injection analysis system.

The use of a factorial design for the response exploration of a flow injection (FI) system is described and illustrated by FI spectrophotometric determination of paraquat. Variable response (absorbance) is explored as a function of the factors flow rate and length of the reaction coil. The present study was found to be useful to detect and estimate any interaction among the factors that may affect the optimal conditions for the maximal response in the optimization of the FI system, which is not possible with a univariate design. In addition, this study showed that factorial experiments enable economy of experimentation and yield results of high precision due to the use of the whole data for calculating the effects.

Analysis of Variance↗
PubMed1991

[Solvent extraction-flow injection analysis for determination of trimethoprim in compound preparations].

Trimethoprim (TMP) in four pharmaceutical preparations (compound sulfamethoxazol tablets, compound tetracycline tablets, compound trimethoprim and sulfamethoxazol tablets; and compound berberine injection) is determined by solvent extraction-flow injection spectrophotometry. It can be extracted into chloroform directly, and the absorbance at a wavelength of 280 nm of the organic phase is measured after phase separation. The manifold comprises two streams. The sample is injected into a 0.2 mol/L NaOH carrier stream, and extracted with chloroform in a 200-cm coil (ID 0.7 mm) after a 50 cm reaction tube (ID 1.0 mm). Calibration graph is linear in the range of 25-150 micrograms/ml. The average recovery is 101.4% with a relative standard deviation of 1.1%. The proposed system permits the analysis of about 50 samples per hour. Precise results in agreement with those obtained with official methods are achieved.

Drug Combinations↗
PubMed1999

Improvement in the determination of mancozeb residues by the carbon disulfide evolution method using flow injection analysis.

The sample decomposition of the carbon disulfide evolution method for the determination of dithiocarbamate residues was carried out in a closed vial in the presence of hexane. The evolved carbon disulfide was extracted by the organic solvent and injected in a flow system for its quantification as copper complex. The conditions for batch decomposition, flow injection determination, and association of both were investigated with sodium diethyldithiocarbamate as model substance. An one-channel flow system was employed where the carrier stream was the ethanolic ethylenediamine/copper solution. The determination range was of 0. 01-1.26 microg of CS(2), with a relative standard deviation of 0.06% (n = 10), with a sample throughput of 45 samples/h. The association of the batch decomposition with the flow system was carried out with the fungicide mancozeb and was applied to the analysis of its residue in potato, lettuce, cucumber, and green bean crops. The approach allowed the analysis of 11 samples in triplicate in 2 h, with recoveries between 85% and 92% and relative standard deviation about 2%.

Carbon Disulfide↗
PubMed1999

Flow injection analysis of intracellular beta-galactosidase in Escherichia coli cultivations, using an on-line system including cell disruption, debris separation and immunochemical quantification.

A continuous integrated process for on-line quantification of intracellular components has been developed. By applying the concept of expanded micro-beds in a flow injection system it was possible to first perform on-line cell disintegration followed by an on-line binding assay for quantification of a reporter protein (beta-galactosidase) from the cell interior. The disintegration process involved the use of an expanded bed with immobilised lysozyme followed by ultrasonic treatment in a flow-through cell. The cell debris does not interfere in the binding assay as it is carried out in an expanded bed. The time for an assay cycle is at present approx. 35 min. This integrated system can be used for quantification of proteins down to at least 10(-7) mol/L.

Calibration↗
PubMedDate not supplied

Flow injection analysis of tetracyclines using inhibited Ru(bpy)3(2+)/tripropylamine electrochemiluminescence system.

Tetracyclines (TCs) were found to strongly inhibit the electrochemiluminescence (ECL) from the Ru(bpy)3(2+)-tripropylamine system when a working Pt electrode was maintained at 1.05 V (vs. Ag/AgCl) in pH 8.0 carbonate buffer solution. On this basis, a flow injection (FI) procedure with inhibited electrochemiluminescence detection has been developed for the determination of tetracycline (TC) and oxytetracycline (OTC). Under the optimized condition, the linear ranges of 2.0 x 10(-8)-1.0 x 10(-5) and 1.0 x 10(-8)-1.0 x 10(-5) g/mL and the detection limits of 4.0 x 10(-9) and 3.8 x 10(-9) g/mL were obtained for TC and OTC, respectively. The relative standard deviations (RSD) were 0.68% and 1.18% for 5.0 x 10(-7) g/mL TC and OTC (n = 13), respectively. The method showed higher sensitivity than most of the reported methods. It was successfully applied to the determination of tetracycline in a Chinese proprietary medicine, Tetracyclini and Cortisone Eye Ointment, and the residues of tetracycline in honey products. The inhibition mechanism has been proposed due to an energy transfer between electrogenerated Ru(bpy)3(2+)* and benzoquinone derivatives at the electrode surface.

Electrochemistry↗