Search results for "potassium"
showing 10 items of 930 documents
Analytical strategy photodegradation/chemiluminescence/continuous-flow multicommutation methodology for the determination of the herbicide Propanil
2006
The present paper is dealing with an analytical strategy based on coupling photodegradation, chemiluminescence and multicommutation continuous-flow methodology for the determination of the pesticide Propanil, a common herbicide. The pesticide solution is inserted as small segments sequentially alternated with segments of the solution for adjusting the suitable medium for the photodegradation. Both flow-rates (sample and medium) are adjusted to required time for photodegradation, 2.0 min; and then, the resulting solution is also sequentially inserted as segments alternated with segments of the oxidizing solutions system, 1.00 x 10(-4) mol 1(-1) potassium permanganate in 2.00 mol 1(-1) sulphu…
FI-on line photochemical reaction for direct chemiluminescence determination of photodegradated chloramphenicol.
2002
Abstract A new, simple, clean and selective flow injection strategy based on the tandem photochemical reaction-chemiluminescence detection was applied to the determination of chloramphenicol. The determination is based on the on-line photodegradation of the drug in a glycine buffer at pH 8.8 by using a photoreactor consisting of 697 cm×0.5 mm PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. Photodegradated chloramphenicol is detected by direct chemiluminescence of resulting photo-fragments and their subsequent reaction with potassium permanganate in sulfuric acid medium as oxidant. The method allows the chemiluminescence determination of compounds which do not exhibit n…
Flow injection-chemiluminescence determination of octyl dimethyl PABA in sunscreen formulations
2002
Abstract A sensitive flow injection (FI) procedure was developed for the determination of the UV-filter octyl dimethyl PABA in sunscreen formulations based on its chemiluminescence (CL) induced by potassium permanganate in sulfuric acid. Both second-order and log–log calibration graphs can be used to perform the analysis. Ninety injections per hour can be carried out, which means a sample throughput of 18 h −1 if five injections per solution are performed. The limit of detection (3 σ ) was 25 ng ml −1 . The interference effects of the excipient and other UV filters are studied. Sunscreen formulations containing octyl dimethyl PABA were analysed by both the proposed FI-CL method and a liquid…
Use of micellar mobile phases for the chromatographic determination of clorazepate, diazepam, and diltiazem in pharmaceuticals
2001
An ODS-2 column, a micellar mobile phase of high elution strength containing 0.1M sodium dodecyl sulfate and 3% (v/v) butanol, and ultraviolet detection at 230 nm are used for the determination of either of two benzodiazepines (clorazepate and diazepam) and a benzothiazepine (diltiazem) in pharmaceuticals. The procedure is shown to be competitive against conventional chromatography with methanol-water mobile phases, especially for diltiazem. The composition of the micellar mobile phase is selected using a predictive strategy based on an accurate retention model and assisted by computer simulation. Calibration graphs are linear at least in the 2.5 to 20 microg/mL, 4 to 20 microg/mL, and 5 to…
Enhanced flow-injection–chemiluminometric determination of sulphonamides by on-line photochemical reaction
2003
Abstract The viability of the tandem photochemical reaction-chemiluminescence detection has been studied for an heterogeneous group of sulphonamides (sulphamethoxazole, sulphadiazine, sulphamerazine, sulphamethoxypyridazine, sulphacetamide, sulphadimidine, sulphanilamide, sulphathiazole and sulphaguanidine) using sulphamethoxazole (whose chemiluminescent behaviour has not been previously reported) as a test substance. The ‘on-line’ photochemical-reaction of sulphonamides provides an enhancing influence on the chemiluminometric response of the drugs during their oxidation by potassium permanganate in sulphuric acid medium (sulphamethoxazole, sulphacetamide, sulphadimidine and sulphanilamide …
A chemiluminescence flow-based procedure for determination of carbaryl in natural waters exploiting multicommutation and enzymatic reaction
2007
A chemiluminescence procedure for the determination of carbaryl in natural waters using acetylcholinesterase and choline oxidase is described. The flow system designed to implement multicommutation approach controlled by microcomputer comprised five solenoid valves, two columns with immobilized enzymes on controlled pore glass beads and chemiluminometric flow cell. In the best experimental conditions a linear response ranging from 25 to 700 µg L-1 carbaryl was obtained. Water samples were spiked with carbaryl in order to access the accuracy and recoveries between 95 and 101% were obtained for a concentration level ranging from 25 to 100 µg L-1 carbaryl. Detection limit and variation coeffic…
eta1-Allypalladium complexes with tridentate PNP’ ligand for the assembly of modified Screen Printed Electrodes: an electrochemical study.
2015
Specific Pd-based organometallic complex, in particular the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4 was used for the assembly of chemically modified Screen Printed Electrodes (SPEs) and their electrochemical reactivity was also investigated. For this purpose potassium ferricyanide, hexaammineruthenium(III) chloride, sodium hexachloroiridate-(III) hydrate, ascorbic acid (AA), uric acid (UA), acetaminophen (Ac), guanine (G) and adenine (A) were used to study the electron-transfer processes, which occurred at modified SPEs, fabricated by using the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4, applying the drop casting procedure. Interesting results were obtained in the case of the guanine (G) quantitative detection,…
Flow injection flame atomic spectrometric determination of iron, calcium, magnesium, sodium and potassium in ceramic materials by using a variable-vo…
1993
A series of different ceramic materials, such as porcelain, feldspar, kaolin, varnish, clay and stoneware have been analyzed. Iron, calcium and magnesium have been determined in these materials by flame atomic absorption and sodium and potassium by flame emission. The use of a variable-volume injector enables one to carry out these analyses in a flow system (after fusion of samples with lithium metaborate) and does not require different dilutions for the determination of each type of sample considered, nor the use of different flow injection manifolds. The developed procedure provides a limit of detection of 100 μg/l for Na, 70 μg/l for Ca, 50 μg/l for both Fe and K and 8 μg/l for Mg. The c…
Atomic-absorption spectrometric determination of calcium, magnesium and potassium in leaf samples after decomposition with molten sodium hydroxide
1991
Abstract The decomposition of standard leaf samples of varied origin and nature by fusion with sodium hydroxide in an open system has been studied. The use of sodium nitrate as an auxiliary agent facilitated the mineralization of most of the samples. The solutions obtained were analysed for calcium, magnesium and potassium by flame atomic-absorption spectrometry. The method is fast and quite precise, with absolute standard deviations of 0.04–0.13, 0.002-0.03 and 0.04–0.12% for calcium, magnesium and potassium contents of O.8-5.0, 0.13–0.48 and 0.36–2.2% respectively. The limits of detection (μg/ml) in the determination step were 0.10 for calcium, 0.011 for magnesium, and 0.09 for potassium.
Automated determination of reboxetine by high-performance liquid chromatography with column-switching and ultraviolet detection.
2000
A fully automated method including column-switching and isocratic high-performance liquid chromatography (HPLC) was developed for quantitative analysis of the new antidepressant reboxetine, a noradrenaline reuptake inhibitor. After serum injection into the HPLC system and on-line sample clean-up on a silica C8 (10x4.0 mm I.D.) clean-up column with an eluent consisting of 2.5% acetonitrile in deionized water, the chromatographic separation was performed on an analytical column (Lichrospher CN; 250x4.6 mm I.D.) with an eluent of acetonitrile-aqueous potassium phosphate buffer (0.008 M, pH 6.4) (50:50). The UV detector was set at 273 or 226 nm. The limit of quantification was about 15 ng/ml at…