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At least 127 records · Page 7Linked to original sources
PubMed1994

The glutamate biosensor and its application to flow injection analysis system.

A micro-enzyme electrode was fabricated by cross-linking L-glutamate oxidase with glutaraldehyde on aminopropyl-platinized platinum wire. A flow injection analysis system with glutamate sensor was used for L-glutamate determination. The peak current is linearly related to the L-glutamate concentration in the range of 0.02-2.0 mM, with good performance, accuracy (CV = 0.4%), fast response (< 60s), and stability (> 20 days). The system was applied to determine the concentration of L-glutamate in a fermentation broth. The recovery rate was in the range of 98.7-107.5%.

Amino Acid Oxidoreductases↗
PubMed1993

Improved flow injection analysis (FIA) method for determining selenium in biological samples, and the effect of captopril administration on selenium levels and glutathione peroxidase activity in rat.

An improved flow injection analysis (FIA) method has been developed for the determination of trace selenium in biological samples, and this method has been applied to investigate the effect of captopril, an antihypertensive drug having a thiol group, on selenium concentrations in the rat blood, liver and urine. After oral administration of captopril, selenium levels in the blood decreased, while those in the liver increased significantly. However, no pronounced effect was observed on the urinary excretion rate. The glutathione peroxidase activities in the blood and the liver were comparable to the changes in the selenium levels.

Administration, Oral↗
PubMed1992

Flow-injection analysis for malondialdehyde in plasma with the thiobarbituric acid reaction.

A simple, precise, and rapid method to measure plasma malondialdehyde (MDA) was developed by use of solvent extraction--flow-injection analysis. The reagent solution, containing thiobarbituric acid (TBA), 5 g/L in 100 mL/L phosphoric acid, and extraction solvent (methylisobutyl ketone, MIBK) were propelled with a double-plunger micropump at a flow rate of 0.3 mL/min, and 20 microL of sample was introduced into the reagent stream. After TBA-MDA reactant was extracted into MIBK, the organic phase was continuously separated by a successive phase-separation system equipped with two phase separators, and the absorbance of the TBA-MDA reactant was measured at 532 nm. This approach resulted in excellent sensitivity, a CV of < 1.5%, a good correlation with the conventional manual method, and a sampling frequency of 7 samples/h, suggesting that this semiautomated method is suitable for measuring plasma MDA.

Animals↗
PubMed1992

Colorimetric determination of free and total cholesterol by flow injection analysis with a fiber optic detector.

A flow injection method for the determination of total and free cholesterol is presented. Cholesterol esterase and cholesterol oxidase are immobilized on aminoalkyl glass beads. The beads are packed into a tubular glass reactor. The cholesterol esters traversing through the esterase reactor are cleaved to cholesterol and fatty acids. The oxidase reactor converts cholesterol to cholest-4-en-3-one and hydrogen peroxide is generated. The sample stream is merged with reagent streams consisting of a peroxidase solution and a solution of 2,2'-azino-bis-(3-ethyl-benzthiazoline-6-sulfonic acid) diammonium salt, and a hydrogen peroxide-dependent color reaction takes place in a short coiled reactor. The signal is monitored by means of fiber optic instrumentation. Cholesterol concentration can be related to the absorption of the oxidized dye form at a wavelength of 425 nm. The working range is 0.5-0.8 mmol l-1, and the sample throughputs are 60 and 30 h-1 for free and total cholesterol, respectively.

Cholesterol↗
PubMed1995

Development of a flow injection analysis (FIA) immunosensor for the detection of Escherichia coli.

A flow injection immunoanalysis (FIA) system has been developed for the detection of Escherichia coli in artificially contaminated food samples. Anti-E. coli antibodies were covalently immobilized onto porous aminopropyl glass beads via glutaraldehyde activation to form an immunoreactor. After adsorption of the cells onto anti-E. coli antibody bound glass beads, 4-methylumbelliferyl-beta-D-glucuronide was injected into the system which was then hydrolyzed by the adsorbed E. coli cells containing beta-D-glucuronidase, an enzyme which is very specific to E. coli and to a few other strains of Shigella. Fluorescent 4-methylumbelliferone released from the enzymatic reaction was then detected by a fluorometer. Owing to the specificity of the antibody towards E. coli, the FIA system was very selective for detection of E. coli whereas Shigella boydii, another GUD-positive bacterium, did not give any response. The FIA system was successfully used for detecting as low as 5 x 10(7) CFU/ml E. coli in less than 30 min and was reusable for at least 300 repeated assays. The immunoreactor yielded reproducible results during 3 months of experimentation if stored overnight at 4 degrees C in carrier buffer containing 0.05 to 0.25% Tween 20.

Escherichia coli↗
PubMedDate not supplied

Determination of sulfur dioxide in wines and beverages by flow injection analysis with reductive amperometric detection and electrolytic cleanup.

A new flow injection method is described for the determination of sulfur dioxide in red and white wines and other beverages. A dual-electrode electrochemical detector eliminates interferences by reduction at an upstream coulometric electrode before reductive detection of sulfur dioxide at the amperometric electrode. The data for free and total sulfur dioxide in wines and other beverages agree well with those obtained by the standard aspiration-oxidation method.

Beverages↗
PubMed1992

Flow injection analysis and in-line biosensors for bioprocess control: a comparison.

Miniaturization will unify the different approaches chosen for the application of biosensors in bioprocess control. The most versatile system, which in our opinion is flow injection analysis will be the method of choice for the introduction of biosensors in bioprocess control. A lot of experience will be gained for the future development of miniaturized total chemical analysis systems.

Biosensing Techniques↗
PubMed1994

Flow injection analysis for glucose using an amperometric enzyme electrode based on lipid-modified glucose oxidase as the detector.

The concentration of glucose is determined by a combination of flow-injection analysis with amperometric enzyme sensor detection. The enzyme sensor is prepared by coating a glassy carbon electrode with a layer of lipid-modified glucose oxidase and Nafion: first, a benzene solution of the modified enzyme is placed on the glassy carbon electrode and dried, then a Nafion solution is placed on the electrode and dried. The sensor-based system exhibited a linear response for glucose concentration up to 10 mM with a sampling rate of 250 sample/h, and is stable for 12 weeks after 2000 glucose injections.

Beverages↗
PubMed1980

Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green.

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.

Bromcresol Green↗
PubMed2001

Mass spectrometric confirmation criterion for product-ion spectra generated in flow-injection analysis. Environmental application.

The suitability of a confirmation criterion recently recommended in the Netherlands for gas chromatography with mass spectrometric detection (GC-MS), was evaluated for flow-injection analysis (FIA) with atmospheric pressure chemical ionisation MS-MS detection. The main feature of the criterion is that the relative ion abundances of the four diagnostic ions are taken into account. That is, for lower-intensity peaks, relative standard deviations may be higher; this is an advantage with chemical ionisation MS procedures. A series of triazines and their degradation products were used as test compounds. Tap and surface water samples spiked at 0.33 microg/l were analysed by means of a selected reaction monitoring MS-MS procedure. For all analytes but hydroxysimazine (3 transitions), 4-9 transitions could be selected which invariably met the demands of the criterion. Some of the transitions used originate from the 37Cl isotopic mass of the parent compounds which provides additional structural information. Data for twenty surface water samples analysed by means of FIA-MS-MS as well as GC-MS and liquid chromatography with diode array UV and MS-MS detection gave essentially the same results over the 0.1-1.0 microg/l range. In two samples desethylatrazine was reported by FIA-MS-MS whereas this compound was not detected by GC-MS. For a first test, this is a promising result.

Flow Injection Analysis↗
PubMed1992

Use of various types of column reactors for flow-injection analysis.

Two or three different kinds of immobilized enzymes can be aligned in a minireactor so that sequential enzymatic reactions are carried out from upstream to downstream during flow-injection analysis. A lactate oxidase-catalase reactor, used as precolumn for removing pre-existing lactate in serum before the lactose dehydrogenase (LDH) reactions, was useful for the determination of serum LDH activity, which did not require any blank correction. A sequential glutamate dehydrogenase-glutamate oxidase reactor was also useful for a novel chemiluminometric determination of ammonia. On the other hand, a co-immobilized creatininase-creatinase-sarcosine oxidase reactor, in spite of containing creatininase which catalyses the reversible reaction, was the most efficient for the determination of serum creatinine.

Ammonia↗
PubMed1997

Fast on-line flow injection analysis system for IgG monitoring in bioprocesses.

An automated immunoassay, with one affinity component immobilized on a solid surface, has been developed to monitor the production of different immunoglobulins during mammalian cell cultivation processes. The whole analysis device is based on the principle of flow injection analysis (FIA) and a cartridge with the immobilized affinity component is implemented into the FIA system. This cartridge is filled with a carrier material to which protein G is covalently bound. After sample injection, binding of the IgG on the protein G within the cartridge takes place while after a washing step, the IgGs are eluted by a pH shift, and the IgG concentration is monitored via fluorescence. In the automated immunoassay, undiluted cell free samples from the reactor or from down-stream processing can be analyzed directly. Due to the separation the IgG can be detected without interference from other sample components by protein fluorescence. The results are obtained with analysis times below 6 min. Sample volumes of less than 100 microliters may be used. The assay is sensitive to concentrations from 5 up to 500 micrograms ml-1. Using this FIA-System, immunoglobulins G, produced in different media, were successfully monitored. The results of the assay were validated by ELISA.

Biochemistry↗
PubMed1996

A microdialysis fibre based sampler for flow injection analysis: determination of L-lactate in biofluids by an electrochemically synthesised bilayer membrane based biosensor.

A microdialysis fibre based, low volume sampler is described which can be used in flow injection analysis (FIA) when an on-line dilution of the sample and/or removal of high molecular weight interferents is required. This device used in combination with a lactate amperometric biosensor based on lactate oxidase electrochemically immobilised in a bilayer membrane of poly(o-phenylendiamine) and overoxidized poly(pyrrole) permits the extension of the linear range of response up to 10 mM lactate. Combining microdialysis sampling with FIA and amperometric detection at an interference-free and fast-response biosensor, lactate determination in complex media such as serum, milk and yoghurt can be easily achieved with a high sample throughput and no sample pre-treatment.

Animals↗
PubMed1984

Highly sensitive flow injection analysis of glucose and uric acid in serum using an immobilized enzyme column and chemiluminescence.

A method for the flow injection analysis of glucose and uric acid in serum using immobilized enzymes in column form and chemiluminescence detection is described. The method is based on the determination of chemiluminescence formed by the reaction of a luminol-ferricyanide mixture with hydrogen peroxide which is produced by the action of the respective oxidases on glucose and uric acid. Glucose or uric acid in serum were determined with 1 microliter of the sample at a speed of 120 samples/h without carryover and at an assay time of approximately 10 s. The immobilized glucose oxidase column measured only 1.0 X 5 mm, and the immobilized uricase column 1.0 X 20 mm. The present method gave perfect linearity of the data up to 4.0 g glucose per liter or 0.10 g uric acid per liter with satisfactory precision, reproducibility, and accurate reaction recoveries. Furthermore, the present method was hardly affected by ascorbic acid, while the peroxidase-linked colorimetric method is usually influenced significantly by ascorbic acid. Both column reactors showed good operational stability for a 2-month period, during which time they were repeatedly used for analyses over 2000 times. The results on glucose and uric acid correlated satisfactorily with those obtained by other well-established methods.

Blood Glucose↗
PubMedDate not supplied

Determination of total sulfite in shrimp, potatoes, dried pineapple, and white wine by flow injection analysis: collaborative study.

A method for the determination of total sulfite in shrimp, potatoes, dried pineapple, and white wine by flow injection analysis (FIA) was collaboratively studied by 8 laboratories. In the method, the sample solution is reacted with sodium hydroxide to liberate aldehyde-bound sulfite. The sample stream is acidified to produce SO2 gas, which diffuses across a Teflon membrane in the gas diffusion cell into a flowing stream of malachite green. The degree of discoloration of the malachite green is proportional to the amount of sulfite in the sample solution. Red wine was included in the study but interlaboratory precision for these samples was not satisfactory and correlation with Monier-Williams results was poor. The present method is not recommended for use with these samples. For shrimp, potatoes, dried pineapple, and white wine, average reproducibility (RSDR) of results was 25% for samples at 10 ppm SO2 and 10% for samples at greater than 50 ppm. Overall average reproducibility was 14%. Recoveries of sulfite added to samples averaged 80%. Comparison of FIA with the Monier-Williams method indicated comparable results by the 2 methods. The FIA method has been adopted official first action for determination of greater than or equal to 5 ppm total sulfite in shrimp, potatoes, dried pineapple, and white wine.

Animals↗
PubMed1996

Near-infrared detection of flow injection analysis by acoustooptic tunable filter-based spectrophotometry.

The instrumentation development of a near-infrared (near-IR) spectrophotometer based on an acoustooptic tunable filter (AOTF) and its application as a detector for flow injection analysis (FIA) are reported. In addition to being compact and all solid state, this AOTF-based instrument is very sensitive, has high resolution, and can be rapidly scanned. The latter advantage make it uniquely suited as a detector for FIA, in that it can rapidly record the whole near-IR absorption spectrum of a mixture passing through the FIA flow cell. Subsequent treatment of the recorded spectra with multivariate calibration methods makes it possible to use the FIA, for the first time, for such applications as the simultaneous determination of trace amounts of water and benzene in ethanol. Because all organic compounds absorb light in the near-infrared region, this AOTF-based near-IR detector can serve as a universal detector for FIA; as a consequence, applications of the FIA techniques can be expanded to other areas which are not possible otherwise.

Benzene↗
PubMed1997

Flow injection analysis for measurement of activity of matrix metalloproteinase-7 (MMP-7).

A simple and convenient method for measuring the activity of a recombinant human matrix metalloproteinase 7 (MMP-7, matrilysin) was developed by flow injection analysis (FIA). For this method, purified recombinant MMP-7 zymogen expressed in E. coli and the substrate peptide (MOCAc-Pro-Leu-Gly-Leu-A2pr(DNP)-Ala-Arg-NH2) were used. Following the incubation of substrate peptide with activated r-proMMP-7, the resulting fluorescent product peptide (MOCAc-Pro-Leu-GLY) was monitored with a fluorescence detector (lambda ex 328 mm, lambda em 393 mm) without chromatographic separation. In this FIA system, the analysis time is 2 min and the standard curve is linear from 5 to 100 pmol of the product peptide injected. In order to use this FIA system as a method for screening inhibitors against MMP-7, the effects of CaCl2, EDTA and of the tissue inhibitor of metalloproteinase-1, and -2, were tested. A synthetic PRCGXPD-containing peptide (BS-10) was also observed to inhibit MMP-7 activity, with an IC50 value of 104 microM. Thus, it was concluded that the activity of r-MMP-7 can be reliably measured by the proposed system. Furthermore, to confirm the utility of this FIA system as a screening method, the inhibitory activity of the MMP-related substance in Joro spider (Nephilia clavata) venom was measured by this method. This inhibitory activity was observed in an extract of a venom diluted 1000-fold. Thus, the FIA method is not only simple and quick, but also sensitive enough to screen and analyze the inhibitory properties of a large number of test compounds.

Enzyme Inhibitors↗
PubMed2000

Rapid and selective determination of ammonium by fluorimetric flow injection analysis.

Selective and sensitive procedures for the determination of ammonium in river water and diluted urine were developed by using flow injection analysis equipment. The methods are based on the derivatization of ammonia with o-phthaldehyde (OPA) and thioglycolate under alkaline conditions. The formed isoindole derivative is detected fluorimetrically at an excitation wavelength of 415 nm and an emission wavelength of 485 nm. The derivatization only takes 15 to 20 s at room temperature to achieve the maximum sensitivity. The optimized OPA reagent shows a surprisingly high selectivity for ammonium in the presence of many primary amines. With respect to the analysis of turbid and fluorescent sample solutions the selectivity can be improved by separating the ammonia through a microporous membrane from the OPA reagent. Without this separation step ammonia can be detected in the range between 0.05 and 100 microM with excellent linearity. After the insertion of an optimized membrane separation cell ammonia can be determined in the linear range between 0.2 microM and 20 mM.

Amines↗