SEARCH · Search PubMed

Results for “Flow Injection Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources

PubMed1990

Competitive heterogeneous enzyme immunoassay for theophylline by flow-injection analysis with electrochemical detection of p-aminophenol.

A competitive enzyme-linked immunoabsorbent assay based on the flow-injection amperometric detection of p-aminophenol has been investigated with use of the materials and general procedure of a commercial kit for the determination of theophylline in human serum. The antibody is immobilized on glass beads, and the enzyme label is alkaline phosphatase (EC 3.1.3.1). The high currents generated during the electrochemical detection allowed a rapid (35 min) and simple determination of theophylline throughout its therapeutic range (10-20 mg/L) and also in the subtherapeutic range (detection limit of about 80 micrograms/L).

Aminophenols↗

PubMed2006

Electrochemical determination of minoxidil in different pharmaceutical formulations by flow injection analysis.

The electrochemical behavior and amperometric-FIA quantification of minoxidil at a glassy carbon electrode is described. The procedure is based on electrochemical oxidation at 0.800 V (vs. Ag/AgCl/NaCl(3 M) in a phosphate buffer solution. Minoxidil was determined over the range 1 x 10(-7) - 1 x 10(-4) M. Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance. The optimal conditions were: working potentials, 0.800 V; flow rate, 0.74 mL min(-1); and solution pH 7.0. This system allowed a sampling rate of 120 samples per hour without any pretreatment. The proposed method was used for minoxidil quantification in pharmaceutical preparations with satisfactory results. The accuracy of FIA-amperometric method was established by a comparison with the conventional UV determination technique using a paired t-test indicating the absence of systematic errors.

Electrochemistry↗

PubMed2005

Potentiometric flow injection analysis of mebeverine hydrochloride in serum and urine.

Four PVC membrane electrodes for the determination of mebeverine hydrochloride (MvCl) were fabricated and fully characterized in terms of composition, life span, usable pH range, working concentration range and temperature. The membranes of these electrodes consist of mebeverinium-silicotungstate (Mv-ST), silicomolybdate (Mv-SM), phosphotungstate (Mv-PT), or phosphomolybdate (Mv-PM) ion-associations dispersed in PVC matrix with dibutyl phthalate plasticizer. The electrodes showed near-Nernstian response over the concentration range of 4.0 x 10(-6) to 1.0 x 10(-2)M MvCl and were applied to the potentiometric determination of mebeverinium ion in pharmaceutical preparations, serum and urine in steady state and flow injection (FI) conditions with average recoveries of 96.4-102 % and relative standard deviations of 0.132-1.86%. The electrodes exhibit good selectivity for MvCl with respect to a large number of inorganic cations, organic cations, sugars and amino acids. The sensitivities of these electrodes are high enough to measure as low as 1.86 microg/ml of MvCl which permit the determination of the Ksp values of the ion-associates used. The proposed potentiometric methods offer the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored sample solutions.

Flow Injection Analysis↗

PubMed2003

Determination of nabumetone in pharmaceutical formulation by flow injection analysis (FIA) with UV-detection.

A precise and accurate FIA method for the quantification of nabumetone (NAB) in pharmaceuticals is described. The best suitable carrier solvent system consisted of ethanol: water (30:70 v/v). Sample solution (4.7 x 10(-6) M NAB) was prepared in this solvent and injected to the instrumental system at a flow rate of 1.2 ml x min(-1). The signals were detected by a UV detector at 228.8 nm. The calibration curves of NAB was linear in the concentration range of 1.4 x 10(-6) M-2.8 x 10(-5) M. The intra- and inter-assay precision were less than 2.6%. The method exhibited a good linearity with the correlation coefficients. The LOD and LOQ values were found to be 4.4 x 10(-7) and 1.3 x 10(-6) M, respectively. The effects of the tablet excipients were insignificant at the 95% probability level. The calculated tablet content was 99% which is agreement with the ranges stated by pharmacopoeias.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2003

A new approach to the integrated calibration in flow injection analysis.

A new proposal how to perform the analytical procedure according to the integrated calibration method is presented. An original flow injection system has been designed for this purpose. When using only a single standard solution, the measurement information gathered during a single analytical course permits construction of four calibration graphs and calculation of as many as four independent estimations of the analyte concentration in the sample examined. As the calibration method applied integrates the set of standards method and the standard addition method, the analytical estimations may be obtained in both the interpolative and the extrapolative manner and the final result can be effectively verified in terms of accuracy. The system developed was experimentally tested on the example of spectrophotometric determination of chromium. It has been proved to be capable of saving time and reagents as well as providing reliable analytical results. Owing to the instrumental simplicity and analytical efficiency the system is expected to be useful for routine analysis.

Calibration↗

PubMed2004

Determination of pressure-temperature coordinates of liquid-vapor critical loci by supercritical fluid flow injection analysis.

Knowledge of phase behavior as sample is transferred through a chromatograph is necessary for the user to either take advantage of desirable effects, such as peak focusing possibilities, or to avoid disastrous peak broadening. Users staying within the norms of conventional chromatographic techniques may not realize the phase behavior events that might be happening or that might be avoided by virtue of the parameter values they use. However, users working with unconventional conditions or with unconventional fluids, such as near-critical or supercritical fluids, must have an awareness of phase behavior through their chromatograph to ensure success. Complete phase diagrams of binary fluids are rare. However, most chromatographic parameters can be set using only knowledge of the temperature and pressure coordinates of the appropriate critical locus. These coordinates can be quickly determined for Type I binary mixtures using chromatographic equipment and a peak-shape observation technique to perform a simple flow injection experiment. Results and chromatographic applications of this knowledge will be summarized.

Chemical Phenomena↗

PubMed2001

Simultaneous determination of Cd(II), Cu(II) and Pb(II) in surface waters by solid phase extraction and flow injection analysis with spectrophotometric detection.

A method for heavy metal monitoring using spectrophotometric detection is presented. Traces of Cu(II), Pb(II) and Cd(II) at the low microg l(-1) level can be determined simultaneously after both selective removal of metal interferences and preconcentration using 'extraction chromatographic resins'. Lewatit TP807'84, which contains di(2,4,4-trimethylpentyl)phosphinic acid as active component, was used as solid adsorbent. Two minicolumns containing this resin were used: one at pH 3.2 for the removal of interferences, such as Zn(II) and Fe(III), and the other at pH 5.5 for the selective preconcentration of the target analytes. Spectrophotometric determination used FIA methodology with sulfarsazene as chromogenic reagent and partial least-squares multivariate calibration. The method was successfully applied to the analysis of surface waters from the Llobregat river and ground water samples from wells in the Guadiamar basin. Accuracy, expressed in terms of recoveries, was in the range 80-120% and relative standard deviations were below 10%.

Cadmium↗

PubMed2000

Chemiluminescence determination of thioridazine hydrochloride by flow-injection analysis.

Hydrogen peroxide, potassium permanganate, potassium dichromate, potassium hexacyanoferrate(III), cerium(IV) sulphate and sodium peroxidisulphate have been tested as potential reagents for chemiluminescence generation from the oxidation of phenothiazine derivatives. Only with potassium permanganate in acidic medium were satisfying results achieved. A total of 13 different phenothiazine derivatives produce luminescence of different intensities on oxidation. Thioridazine hydrochloride was chosen to develop a rapid and simple method for its determination in pharmaceutical formulations. The limit of detection is 1.2 x 10(-6) mol l(-1), and 110 samples per hour can be determined.

Antipsychotic Agents↗

PubMed1994

Amperometric flow-injection analysis of creatinine based on immobilized creatinine deiminase, leucine dehydrogenase and L-amino acid oxidase.

Leucine dehydrogenase/L-amino acid oxidase was proposed as an enzymatic conversion system for ammonia and its application to amperometric assay of creatinine was investigated. Ammonia formed by creatinine deiminase catalyzed hydrolysis of creatinine was converted to L-leucine by leucine dehydrogenase, and the oxidation of L-leucine by L-amino acid oxidase was detected with an oxygen electrode. Two approaches were proposed to overcome the problem of endogenous ammonia and L-amino acids. The first was using glutamate dehydrogenase prereactor to remove endogenous ammonia; endogenous L-amino acids were corrected by a separate run. In the second approach, endogenous ammonia and L-amino acids were simultaneously compensated with a two-channel system. It resulted in double peak recording that the flow was split and rejoined between the two ends of creatinine deiminase reactor and a delay coil and a reference column were properly set at one of the two-channels. One gave the sum response of all responsible compounds, the other that of endogenous interferences except creatinine. Both approaches were applied to creatinine assay in urine and the results showed a good agreement with those obtained from the Jaffe method.

Amino Acid Oxidoreductases↗

PubMed2006

Sequential flow injection analysis system on-line coupled to high intensity focused ultrasound: green methodology for trace analysis applications as demonstrated for the determination of inorganic and total mercury in waters and urine by cold vapor atomic absorption spectrometry.

A new concept is presented for green analytical applications based on coupling on-line high-intensity focused ultrasound (HIFU) with a sequential injection/flow injection analysis (SIA/FIA) system. The potential of the SIA/HIFU/FIA scheme is demonstrated by taking mercury as a model analyte. Using inorganic mercury, methylmercury, phenylmercury, and diphenylmercury, the usefulness of the proposed methodology for the determination of inorganic and total mercury in waters and urine was demonstrated. The procedure requires low sample volumes and reagents and can be further applied to all chemical reactions involving HIFU. The inherent advantages of SIA, FIA, and HIFU applications in terms of high throughput, automation, low reagent consumption, and green chemistry are accomplished together for the first time in the present work.

Biosensing Techniques↗

PubMed2001

Highly sensitive determination method for total carbonate in water samples by flow injection analysis coupled with gas-diffusion separation.

A spectrophotometric method for the determination of total carbonate in water samples was developed. The method is based on the color change of an acid-base indicator in relation to the concentration of permeable gas substances through a membrane. By using a new portable FIA system equipped with a gas-diffusion unit, a highly sensitive and on-site determination of total carbonate in aqueous solutions was investigated. A new color-change system with 4-(2',4'-dinitrophenylazo)-1-naphthol-5-sulfonic acid (DNN5S) was developed. Absorbance changes of the reagent solution were measured at 450 nm with a light-emitting diode (LED) as a light source. A new type of gas-diffusion unit was used, and was constructed with double tubing: the inner tubing was a micro porous PTFE (polytetrafluoroethylene) tubing (1.0 mm inner diameter and 1.8 mm outer diameter, pore size 2 microns, porosity 50%); the outer tubing was made of glass with 2.0 mm inner diameter. The optimized system conditions were as follows: the sample size was 200 microliters, the temperature of the air bath for the gas-diffusion unit was 25 degrees C, and the length of the gas-diffusion unit was 15 cm; each flow rate was 0.3 ml min-1. For measuring carbonate at low concentrations, a method for preparing water with less carbonate was proposed: the carbonate content of the water was decreased down to 5 x 10(-7) M. The calibration graph was rectilinear from 1 x 10(-6) M to 10(-3) M, and the detection limit (corresponding to a signal-to-noise ratio of 3) was 1 x 10(-6) M of carbonate. The relative standard deviation (RSD) of ten measurements of 2.3 x 10(-5) M Na2CO3 solution was 1.9%. The total carbonate in various kinds of water (such as river, sea, rain, distilled and ultra purified) was determined.

Carbonates↗

PubMed1999

Evaluation of data produced by optode arrays under flow injection analysis (FIA) conditions using a partial least squares method (PLS2).

Transient diffuse reflectance spectra in the visible wavelength region from an enzyme optode were evaluated to determine artificial mixtures consisting of penicillin and ampicillin simultaneously. In order to achieve a discrimination of the samples the optode operated at two different working pH values. Using an appropriate FIA modus a linear range in the increase and decrease of the time-dependent signal was registered which could be easily fitted by means of ordinary linear regression. In this way characteristic static and dynamic features of the enzyme catalyzed reaction could be extracted for the evaluation by partial least-squares (PLS). The pre-processed raw data were differently weighted and the optimal number of primary factors was each selected by full cross validation. The interpretation of the spectral loadings and the correlation matrix identifies redundant variables resulting in a model with an optimal number of variables. The results obtained with this model show that the straightforward linear regression can be a sufficient approach to avoid the introduction of systematic errors in on-line pre-processing of data.

Ampicillin↗

PubMed1987

Measurement of protein using flow injection analysis with bicinchoninic acid.

We have used the bicinchoninic acid reagent developed by Pierce Chemical Co. to measure proteins in a simple flow injection analyzer. The sensitivity is comparable to that of the Lowry method and no pipetting of reagents is needed. Results are obtained in less than 1 min and samples may be run at a rate of 60/h. The response is linear over a range of protein concentration (0-10 micrograms) and sample size (5-20 microliters) convenient for most analytical requirements. A peristaltic pump, a controlled-temperature water bath, and a spectrophotometer with flow cuvette are the only special apparatus required.

Proteins↗

PubMed1996

Development of an on-line control system for the cultivation of animal cells in a hollow-fiber reactor using flowing injection analysis and a visual programming language.

A system for the independent control of ammonia and glutamine in a hollow-fiber reactor has been developed. On-line analysis of the two chemical species was performed using FIA. A custom-made program has been written to fully automate the FIA, to perform measurements, calibrations and data acquisition, and to activate two peristaltic feed pumps. Diagnostic tests were also automatically performed in order to identify, and in some cases eliminate, erroneous measurements and calibrations due to instrument failures. For this purpose, a visual programming language (LabVIEW) has been chosen. Ammonia concentration was controlled by varying the medium supply rate to the hollow-fiber reactor which was shown to behave like an ideal-stirred tank reactor. The glutamine concentration was controlled through the intermittent activation of a pump delivering a concentrated solution of this species to the reactor. This control system was tested with a culture of hybridoma cells at three different ammonia and one glutamine set-points. The hollow-fiber reactor was successfully operated automatically for more than 1200 h with ammonia and glutamine concentrations accurately controlled at non-limiting levels. The visual programming environment was found to be reliable and highly suitable for the development of custom programs for bioprocess control.

Animals↗

PubMed2000

Determination of beta-amylase activity by a fluorimetric 2-p-toluidinylnaphthalene-6-sulfonate flow-injection analysis (2, 6-TNS-FIA) method, using amylose and amylopectin as substrates.

2-p-Toluidinylnaphthalene-6-sulfonate (2,6-TNS) is a compound which is barely fluorescent in pure water but whose fluorescence can be strongly enhanced if the environment becomes hydrophobic, i.e. by the addition of suitable substrates such as proteins or 1, 4-alpha-D-glucans. The enhancement of fluorescence results from the formation of a 2,6-TNS/substrate complex. For linear and ramified 1, 4-alpha-D-glucans, the fluorescence intensities of the complexes depend linearly on their concentrations but nonlinearly on their average molecular weights (AMW). Thus, the fluorescence detector acts simultaneously as a linear detector concerning the concentration of 1,4-alpha-D-glucan and as a nonlinear mass-selective detector concerning its AMW. These properties have been used for the development of a fluorimetric 2,6-TNS-FIA methodology for the determination of beta-amylase activity, using amylose and amylopectin as substrates. The experimental data points, corresponding to the concentration of "detectable" substrate vs depolymerization time, were fitted using a two-parameter exponential decay curve, and the depolymerization rates at time zero were calculated. The depolymerization rates at time zero vs the corresponding initial substrate concentrations were fitted using the Michaelis-Menten hyperbola and the enzymic constants k(3) and K(m) for amylose (5.93 x 10(-3) g/microKat. min and 1.49 g/L, respectively) and for amylopectin (7.40 x 10(-3) g/microKat+. min and 1.65 g/L, respectively) were determined.

Amylopectin↗

PubMed2000

Gold electrodes from recordable CDs for mercury quantification by flow injection analysis.

The development of a new methodology for the construction of very efficient flow cells for mercury detection by potentiometric stripping analysis, employing the thin gold layer of recordable CDs as working electrode is reported. This new source of electrodes (CDtrodes) show very attractive performance, similar to that obtained with commercial gold electrodes, with superior versatility. The low cost of this new source of "gold electrodes" allows a frequent replacement of the electrode, avoiding cumbersome clean-up treatments. Various experimental parameters have been optimized to yield low detection limits (0.25 ng/mL of mercury for 5 min deposition at 0.3 V) and good precision (standard deviation of 1.9% was obtained for 15 repetitive measurements using 10 ng/mL of mercury). Standard curves were found to be linear over the range of 0.5-100 microg L(-1) of mercury. The flow cells developed were used for the quantification of mercury in oceanic and tap water.

Journal Article↗

PubMed2003

On-line separation and preconcentration of silver ion on amidino-thiourea immobilized glass beads packing in flow injection analysis with atomic absorption spectrometric detection.

Amidino-thiourea immobilized glass beads (AGB I) were prepared and used as the microcolumn packing for the flow injection (FI) on-line separation and preconcentration of Ag(I) coupled with atomic absorption spectrometry (AAS) determination. Base metal ions and anions with a concentration of 2.0 mg mL(-1) had no interference with the determination of Ag(I). The limit of detection (LOD) of Ag(I) for a preconcentration time of 60 s with a sampling flow rate of 5.0 mL min(-1) for 40.0 ng mL(-1) of Ag(I) were 0.50 ng mL(-1) with the peak-height absorbance mode and 1.26 ng mL(-1) with the peak-area absorbance mode, respectively. The relative standard deviations (RSD) of 7 replicate determinations were 0.9% and 0.7% for the peak-height absorbance (H) and the peak-area absorbance (A), respectively. The method was successfully applied to the determination of Ag(I) in ore samples.

Journal Article↗

PubMed1991

[Determination of tetracyclines by flow injection analysis].

An accurate, convenient and fast method was proposed for the determination of tetracyclines (tetracycline, chlortetracycline, oxytetracycline, doxycycline and methacycline) and their preparations by flow injection detector based on tetracycline flow-through sensor. The parameters affecting the measurement were discussed. The detector can respond to tetracycline, chlortetracycline, oxytetracycline, doxycycline and methacycline, at the same time. Their slopes are 51-55 mV/decade over the concentration range of 10(-2)-5 x 10(-5) mol/L at pH 1.5-3.5. The results obtained are in good agreement with those by biological assay (less than 3% deviation). One hundred samples can be determined in an hour.

Electrochemistry↗