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PubMed2004

Generation and destruction of unstable reagent in flow injection system: determination of acetylcysteine in pharmaceutical formulations using bromine as reagent.

A flow injection spectrophotometric procedure was developed for determination of acetylcysteine in sachets and liquid formulations. The determination of this drug was carried out by reacting it with bromine chemically generated in flow injection system monitored continuously at 400 nm. Acetylcysteine reacts with bromine causing a decrease in the absorbance that is proportional to the analyte concentration. The bromine in excess was destroyed on-line by an ascorbic acid solution before the discard. The calibration curve for acetylcysteine determination was linear in the concentration range from 1.6 x 10(-4) to 1.6 x 10(-3) mol/l with a detection limit of 8.0 x 10(-5) mol/l. The relative standard deviation (R.S.D.) was lesser than 1.2% for a solution containing 5.3 x 10(-4) mol/l acetylcysteine (n=10), and 60 determinations per hour were obtained.

Acetylcysteine↗
PubMed2005

Flow-injection chemiluminescence determination of phentolamine based on its enhancing effect on the luminol-potassium ferricyanide system.

It was found that the light emission produced by the oxidation of luminol by potassium ferricyanide in the basic medium was enhanced by phentolamine, a drug recently used to treatment of male and female sexual dysfunction. The optimum conditions for this chemiluminescent reaction were studied in detail by a flow-injection system. A new, simple and rapid method has been developed under the optimum conditions for determination of phentolamine. This method has the advantages of high sensitivity, good reproducibility and low detection limit. On the basis of investigation of chemiluminescent, fluorescent and UV spectra of phentolamine in basic solution containing potassium ferricyanide and luminol, a possible mechanism of this reaction was proposed. In the optimum conditions, CL intensities are proportional to concentrations of the phentolamine in the 0.01-1 microg/mL range. The limit of detection is 3.0 ng/mL for phentolamine. The method has been applied to the determination of phentolamine in the commercial preparations, synthetic samples and biological fluids with satisfactory results.

Calibration↗
PubMed2005

Chemiluminometric determination of propranolol in an automated multicommutated flow system.

In this work, a fully automated analytical methodology for the chemiluminometric determination of propranolol hydrochloride in pharmaceutical preparations is proposed. The developed procedure was based on the oxidation of propranolol by potassium permanganate in acidic medium and was implemented in a multicommutated flow system. The combined automated actuation of syringe pumps and two-way solenoid valves, under computer control, assured a high versatility in terms of sample and reagent manipulation and an effective run-time control of all analytical parameters, including a time-based insertion that enabled a significant solutions saving and the exploitation of different strategies for sample/reagent mixing. The calibration graph was linear over the range 20-150 mg l(-1) of propranolol hydrochloride with a relative standard deviation lower than 1.6% (n = 7). The results were in agreement with those obtained by the reference procedure with a relative deviation between -3.8 and 3.7% and a sampling rate of about 27 samples h(-1).

Autoanalysis↗
PubMed2005

Sequential-injection determination of traces of disodium phenyl dibenzimidazole tetrasulphonate in urine from users of sunscreens by on-line solid-phase extraction coupled with a fluorimetric detector.

A sensitive and selective method to determine disodium phenyl dibenzimidazole tetrasulphonate (PDT) in the urine of sunscreen users, which is suitable for studies on body accumulation/excretion is proposed. On-line solid-phase extraction allows the analyte to be retained and subsequentely eluted, using a strong anion exchange (SAX) microcolumn. Standard addition calibration was carried out with only one standard. The wavelengths of excitation and emission were 330 and 454 nm, respectively. The method allows PDT to be determined in both, spiked and unspiked human urine samples, without any pre-treatment. Results obtained for spiked urine samples (40-200 ng ml(-1)) showed the accuracy of the method. The mean relative standard deviations (R.S.D.) of the results was 7%. Five volunteers applied a sunscreen lotion containing 5% PDT and their urinary excretion was controlled from the moment of application until the excreted amounts were no longer detectable. The sensitivity of the proposed method is in the order of 1900 ml microg(-1) and the detection limit (3S(y/x)/b) is in the order of 5 ng of PDT, which means 10 ng ml(-1) for a 500 microl injected volume, and this is suitable for the PDT levels found in the urine.

Administration, Topical↗
PubMed2006

Rapid determination of clindamycin in medicine with myoglobin-luminol chemiluminescence system.

A sensitive chemiluminescence method, based on the inhibitory effect of clindamycin on the chemiluminescence reaction between luminol and myoglobin in a flow-injection system, is proposed for the determination of clindamycin. The decrement of chemiluminescence intensity is linear with the logarithm of clindamycin concentration over the range from 0.1 to 70.0 ng ml-1 (r2=0.9995), with the detection limit of 0.03 ng ml-1 (3sigma). At a flow rate of 2.0 ml min-1, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 3.0% (n=5). The proposed procedure was applied successfully to the determination of clindamycin in capsules without any pretreatment process.

Anti-Bacterial Agents↗
PubMed2006

Flow injection chemiluminescent determination of amiodarone in pharmaceutical preparations using photogenerated tris(2,2'-bipyridyl)ruthenium(III).

A flow injection configuration was developed and evaluated for the chemiluminescent determination of amiodarone. The method is based on the reaction of the drug with tris(2,2'-bipyridyl)ruthenium(III), which was generated through the on-line photo-oxidation of tris(2,2'-bipyridyl)ruthenium(II) with peroxydisulfate. Under the optimum experimental conditions, a linear calibration graph was obtained over the range 3.0-60.0 microg ml(-1) with a detection limit of 0.28 microg ml(-1). The proposed method allows 120 injections h(-1) with excellent repeatability and precision (R.S.D. less than 0.5% and 2.8%, respectively) and a reagent consumption of only 0.37 micromol (0.27 mg) of Ru(bpy)(3)Cl(2) x 6H(2)O per determination. The method was successfully applied to the determination of amiodarone in commercial pharmaceutical formulations.

Amiodarone↗
PubMed2006

Determination of hydralazine with flow injection chemiluminescence sensor using molecularly imprinted polymer as recognition element.

A novel flow injection chemiluminescence (CL) sensor for hydralazine determination using molecularly imprinted polymer (MIP) as recognition element is reported. Hydralazine-MIP was prepared through non-covalent copolymerization using methacrylic acid (MAA) monomer, hydralazine template and ethylene glycol dimethacrylate (EGDMA) cross-linker. Particles of the MIP were packed into a v-shape glass tube for on-line adsorption of the analyte of hydralazine. The adsorbed hydralazine could be sensed by its great enhancing effect on the CL reaction between luminol and periodate. The CL intensity is linear to hydralazine concentration in the range from 2x10(-9) to 8x10(-7) g/mL. The detection limit is 6x10(-10) g/mL (3sigma) and the relative standard deviation is 2.8% (n=7) for 8x10(-9) g/mL hydralazine. The selective experiment showed that the selectivity and sensitivity of the CL method could be greatly improved when MIP was used as recognition element in the flow-injection CL sensor. The sensor was reversible and reusable. It could be used for more than 100 times. It has been used directly to determine the hydralazine in human urine.

Flow Injection Analysis↗
PubMed2006

Flow injection chemiluminescence determination of cefadroxil using potassium permanganate and formaldehyde system.

A simple, rapid and precise flow injection chemiluminescence (FI-CL) method is proposed for the determination of cefadroxil and is suitable for application to other antibiotics containing phenolic hydroxyl groups. A possible mechanism for this selectivity is suggested. The method is based on the CL-emitting reaction between cefadroxil and potassium permanganate in sulfuric acid medium, enhanced by formaldehyde (HCHO). Under the optimum conditions, calibration graphs over the ranges of 0.05-0.8 and 1.0-10.0 microg ml(-1) were obtained. The proposed method was successfully applied to the determination of cefadroxil in pharmaceutical formulations with no evidence of interference from common excipients. The detection limit (3sigma) of this method is 25 ng ml(-1) (6.9 x 10(-8) mol l(-1)). The relative standard deviation was less than 2% for 0.4 and 4.0 microg ml(-1) cefadroxil (n = 20). The sample throughput was found to be 120 h(-1).

Anti-Bacterial Agents↗
PubMed2006

Flow-injection chemiluminescent determination of cefprozil using Tris (2,2'-bipyridyl) ruthenium (II)-permanganate system.

A rapid and sensitive chemiluminescence (CL) method using flow-injection (FI) has been developed for the determination of a second generation cephalosporin, cefprozil. The method is based on the CL reaction of cefprozil with acidic potassium permanganate and tris (2,2'-bipyridyl) ruthenium (II), Ru (bipy)3(2+). The CL intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 0.1-3.0 microg ml(-1) with minimum detectability of 0.005 microgml(-1) (S/N=3). The correlation coefficient was 0.9998 (n=6) with a relative standard deviation (%R.S.D.) of 1.63% for 2.0 microgml(-1). The proposed method was successfully applied to commercial tablets. The average percentage recovery (n=6) was 99.9+/-1.40.

Cephalosporins↗
PubMed2006

Determination of paracetamol: historical evolution.

Paracetamol is a common analgesic and antipyretic drug that is used for the relief of fever, headaches and other minor aches and pains. Their determination in pharmaceuticals is of paramount importance, since an overdose of paracetamol can cause fulminating hepatic necrosis and other toxic effects. Many analytical methodologies have been proposed for the determination of paracetamol. The aim of the present study is to evaluate the utility of different techniques for quantification of paracetamol content in pharmaceutical formulations and biological samples.

Acetaminophen↗
PubMed2006

Determination of metoprolol tartrate in tablets and human urine using flow-injection chemiluminescence method.

In this paper, a simple, rapid and sensitive flow-injection chemiluminescence method has been developed for the determination of metoprolol tartrate, which acts as a kind of sensitizer in the chemiluminescence emission from the redox of SO(3)(2-) with Ce(IV) in acidic medium. Under the optimized conditions, the proposed method allows the measurement of metoprolol tartrate over the range of 1.5 x 10(-8) to 7.3 x 10(-6)mol/L with a detection limit of 4.7 x 10(-9)mol/L (3sigma), and the relative standard deviation for 7.3 x 10(-7)mol/L metoprolol tartrate (n=11) is 2.20%. The utility of this method was demonstrated by determining metoprolol tartrate in tablets and human urine sample.

Cesium↗
PubMed2006

Multicommuted flow system employing pinch solenoid valves and micro-pumps. Spectrophotometric determination of paracetamol in pharmaceutical formulations.

A multicommuted spectrophotometric flow-based procedure for the determination of paracetamol in pharmaceutical formulations is proposed. The method is based on the reaction of paracetamol with sodium hypochlorite forming N-acetyl-p-benzoquinoneimine, which reacts with sodium salicylate in alkaline medium producing a blue indophenol dye that was measured at 640nm. The flow system was designed employing four pinch solenoid valves and two solenoid micro-pumps, which were assembled aiming to obtain a compact module, resulting in minimization of reagents consumption and waste generation. Aiming to prove the usefulness of flow system an analytical procedure for paracetamol determination in pharmaceutical formulations was developed. To allow accuracy assessment samples were also analyzed using the AOAC reference method. Applying the paired t-test between results no significant difference at the 95% confidence level was observed. Other profitable features such as a linear response ranging from 5.0 to 125.0mgl(-1) (R=0.9992, n=7), a sampling rate of 60 determinations per hour, a detection limit of 0.4mgl(-1) paracetamol, a relative standard deviation of 1.5% (n=11) for a typical sample solution containing 25.0mgl(-1) paracetamol, reagent consumption of 1.28mg sodium hypochlorite and 6.4mg sodium salicylate per determination were also achieved.

Acetaminophen↗
PubMed2006

Photo-induced chemiluminometric determination of Karbutilate in a continuous-flow multicommutation assembly.

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. The studied calibration range, from 0.1 microg l(-1) to 65 mg l(-1), resulted in a linear behaviour over the range 20 microg l(-1)-20 mg l(-1) and fitting the linear equation: I=(1180+/-30)C+(15+/-5) with the correlation coefficient 0.9998. The limit of detection was 10 microg l(-1) and the sample throughput 17 h(-1). After testing the influence of a large series of potential interfering species, the method was applied to water and human urine samples.

Calibration↗
PubMed2006

Automated determination of flutamide by a validated flow-injection method: application to dissolution studies of pharmaceutical tablets.

The first flow-injection (FI) method for the determination of flutamide--a potent antiandrogen used for the treatment of prostate cancer--is reported. The method is based on the direct measurement of the absorbance of the analyte at 310 nm under flow conditions. Parameters affecting the determination such as detection wavelength, sample injection volume and flow rate were studied and optimized. The assay was validated (linearity, limits of detection and quantitation, accuracy, repeatability, reproducibility and selectivity) for the dissolution studies of flutamide-containing tablets during stability testing. The results were in good agreement with high performance liquid chromatography (HPLC) used as a reference method.

Androgen Antagonists↗
PubMed2004

Highly selective spectrophotometric flow-injection determination of trace amounts of bromide by catalytic effect on the oxidation of m-cresolsulfonephthalein by periodate.

A new flow-injection method is reported for the determination of bromide. The method is based on catalytic effect of bromide on the oxidation of m-cresolsulfonephthalein by periodate in acidic media. The reaction was followed spectrophotometrically by measuring the decrease in absorbance at 528 nm. The influence of pH, reagent concentration and manifold variables on the sensitivity was studied. Under optimum conditions, a calibration graph was obtained in the range of 0.160-20.00 microg ml(-1) bromides with a limit of detection of 0.150 microg ml(-1) bromide. The relative standard deviation for ten replicate measurement of 1.0 microg ml(-1) bromide was 2.1%. The influence of potential interfering ions on the selectivity was studied. The method successes to measure bromide in the presence of other halide ions. The method was used to measure bromide in river water and tap water.

Bromides↗
PubMed2004

Flow injection chemiluninescence for detecting picogram amounts of dobesilate in human urine.

A sensitive method for the determination of dobesilate in pharmaceutical preparations and human urine is described by using controlled-reagent-release technology. The method entailed the use of luminol and periodate, which are immobilized on anion exchange resin and react in alkaline medium, giving chemiluminescence (CL) at 425 nm. Dobesilate was detected by measuring the decrease of CL intensity, and which was observed linear over the dobesilate concentration range of 10-600 pg ml(-1), and the limit of detection was 3.5 pg ml(-1) (3sigma) and a relative standard deviation of less than 3.0%. At a flow rate of 2.0 ml min(-1), the determination of dobesilate, including sampling and washing, could be performed in 0.5 min, giving a throughput of about 120 times per hour. The proposed method has an extremely low limit of detection down to 3.5 pg ml(-1), thus it can be applied directly in the assay of human urine without any pre-treatment. It was also found that the dobesilate concentration reached its maximum after orally administrated for 3.5h, and the excretion ratio in 24h was 58.8% in the body of volunteers.

Calcium Dobesilate↗
PubMed2006

Chemometrics-assisted simultaneous determination of cobalt(II) and chromium(III) with flow-injection chemiluminescence method.

In this paper, a flow-injection chemiluminescence (CL) system is proposed for simultaneous determination of Co(II) and Cr(III) with partial least squares calibration. This method is based on the fact that both Co(II) and Cr(III) catalyze the luminol-H(2)O(2) CL reaction, and that their catalytic activities are significantly different on the same reaction condition. The CL intensity of Co(II) and Cr(III) was measured and recorded at different pH of reaction medium, and the obtained data were processed by the chemometric approach of partial least squares. The experimental calibration set was composed with nine sample solutions using orthogonal calibration design for two component mixtures. The calibration curve was linear over the concentration range of 2 x 10(-7) to 8 x 10(-10) and 2 x 10(-6) to 4 x 10(-9) g/ml for Co(II) and Cr(III), respectively. The proposed method offers the potential advantages of high sensitivity, simplicity and rapidity for Co(II) and Cr(III) determination, and was successfully applied to the simultaneous determination of both analytes in real water sample.

Calibration↗
PubMed2006

Flow injection-chemiluminescence determination of phenol using potassium permanganate and formaldehyde system.

It is found that phenol can react with potassium permanganate in the acidic medium and produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction are in detail studied using a flow injection system. The experiments indicate that under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of phenol in the range 5.0x10(-9) to 1.0x10(-6)gmL-1 with a detection limit (3sigma) of 3x10(-9)gmL-1. The relative standard deviation is 1.2% for 4.0x10(-7)gmL-1 phenol solution in 11 repeated measurements. This method has the advantages of simple operation, fast response and high sensitivity. The method is successfully applied to the determination of phenol in the waste water.

Flow Injection Analysis↗