Recording the real sample distribution and concentration/time functions in flow injection analysis

A rapid and precise assay for peroxide as ‘active oxygen’ in products, by flow injection analysis in a high pressure system with spectrophotometric detection

A method was developed for determination of arsenic by Atomic Absorption Spectrometry - Hydride Generation in Flow Injection Analysis (FIA). The flow injection system was operated in the merging zones configuration, where sample and reagent are simultaneously injected into two carrier streams, HC1 and H2O, respectively. For separation of arsine a continuous gas-liquid separator was designed. The liquid phase flows to a free-running drain while the gaseous phase is purged by nitrogen into the atomization cell. The optimum conditions for the generation of arsine were established as: reaction coil of 50 cm, sample and reagent injected volume of 250 p.L, 1.0% (m/v) solution of sodium tetrahydroborate and 1.0 mol L’1 hydrochloric acid, cell temperature of 900°C, flow rates of 3.6 mL min’1 for hydrochloric acid and tetrahydroborate Solutions and a flow rate of 130 mL min-1 for the carrier gas (N2). Many elements cause interferences in this technique in gaseous and condensed phases. It was found that Mn(II), Pb(Il), Fe(IIl), Cu(II), Ni (II), Zn (II), Al (III) and Cd (II) caused signal reductions for arsenic of at least 10%. The interferences were reduced by using an on-line mini-column with 50 mg of the cation exchange resin Amberlite IRA-120. The interferences in the gaseous phase were caused by Se(IV), Sn(II), Sb(III), Bi(III) and Te (IV). To overcome these efíects, thioureia was used as masking agent. Under the optimum experimental conditions, the detection limit. defined as three times the standard deviation of the blank measurement, was found to be 0,35 ng mL’1 for As(lII) and 0,52 ng mL’1 for As(V). The relative standard deviation of 2,3% for 0,1 mg L’1 As(IIl) and 1,7% for 0,1 mg L’1 As(V) and a sampling rate of about 120 determinations per hour. The method was shown to be satisfactory for determination of traces arsenic in water samples (natural and certificate).

Simultaneous and direct determination of urea and creatinine in human urine using a cost-effective flow injection system equipped with in-house contactless conductivity detector and LED colorimeter

Sequential flow injection spectrophotometric determination of nitrite and nitrate in various samples

A gravity-induced flow injection system for surface plasmon resonance biosensor

An equation was derived for the determination of a stability constant from a flow injection titration experiment in which the product of the reaction is monitored. This equation showed that if the product concentration at the equivalence points of the titration was used as the basis for the calculation, the method was independent of all the variables associated with the flow injection system, provided that a single-line manifold was used. If the system corresponded to that described by the well stirred mixing chamber model, then the time interval between the peaks could be used to determine the ratio of the stoicheiometric coefficients of the reactants. The use of the method is illustrated for the copper(II)-EDTA system giving values for log K in reasonable agreement with the literature values.

A flow injection analysis (FIA) system for evaluation of the antioxidant activity of a compound capable of scavenging a hypochlorite anion (OCl⁻), one of the reactive oxygen species (ROS), was developed. Aminophenyl fluorescein (APF), a fluorescence indicator of ROS, was mixed manually with the test compounds and the mixed solution was injected into the FIA system. The injected solution was reacted in-line with OCl⁻, that was produced by using sodium dichloroisocyanurate in the presence of 0.1 M CH3CO2Na in H2O. The fluorescence intensity of fluorescein generated from non-fluorescent APF was significantly attenuated in compounds that had a scavenging effect on OCl⁻. The precision obtained by the FIA system was satisfactory (relative standard deviation < 5.0%) and a rapid assay within 0.5 min per sample was achieved. The proposed FIA system was used to demonstrate that reduced glutathione, dithiothreitol, and 3-methyl-1-phenyl-5-pyrazolone (edaravone) showed a significant scavenging effect on OCl⁻. Therefore, the proposed FIA system can be used as a screening assay for OCl⁻-scavenging compounds.

Objective To establish a catalytic spectrophotometric method for determination of iodine in water without the use of highly toxic arsenic reagents with good precision and accuracy. Methods A new flow injection catalytic spectrophotometry method for determination of iodine in water was established by combining flow injection analysis (FIA) with a new catalytic spectrophotometry for determination of iodine with no need of arsenic reagent. The standard curve linearity, sample detection limit, precision and accuracy of different iodine content ranges(0 - 250, 0 - 1 200 μg/L) were tested. The test result was compared with that of the arsenic-based catalytic spectrophotometry recommended by the iodine deficiency disorders monitoring program in China(recommended monitoring method). Results A calibration relation of C = aA2 + bA + d (C: iodine concentration, A: measuring absorbance peak area from FIA) of the new method existed in the range of 0 - 250 and 0 - 1 200 μg/L. The linear correlative coefficient were both 0.999 9. The detection limit for iodine in water was 0.3 μg/L. The FIA peak shape of the sample tube with the lowest content is determined, and the sensitive iodine signal is detected. The water samples with different iodine content ranges were determined in parallel for 6 times, and the coefficient of variation (CV) was 0.2% - 2.7%; the recoveries ranged from 95.0% to 105.0%, and the total average recovery was 100.3%. The measured values of water iodine standard material GBW 09113e [(8.2 ± 1.2) μg/L] and GBW 09114d [(62.0 ± 6.0) μg/L] in the standard curve of different iodine contents were all within the uncertainty range of the given value. There was no significant difference between the results of recommended monitoring method and the new method(t = 0.781, P > 0.05). Conclusions The new method for measuring water iodine has a wide standard curve range, high sensitivity, and good precision and accuracy. The instrument is easy to operate, and no need for toxic arsenic reagent. The method is a reliable method for water iodine detection. Key words: Iodine; Water; Arsenic; Flow injection analysis; Catalytic spectrophotometry

For more than a decade, immunoassay methods have held great promise for use not only in their classic clinical applications but also in food, pesticides, process and quality control, industrial fermentations, etc. A great number of publications have appeared in these fields. Flow injection analysis (FIA) is a technique that allows the automatic analysis of a large number of samples and/or continuous monitoring, and it has been proven to be applicable to a variety of analytical problems. Nevertheless, antibody-supported flow injection systems have received relatively little attention. Only recently, the advantage of the specificity inherent to most immune reactions began to be exploited in FIA procedures. Flow injection coupled to immunoassays (FIIA) is arising as a powerful tool for the development of analytical protocols, and the application of FIA techniques is expected to contribute enormously in improving the speed and quality of immunoassays. This article gives an overview on the application...

A sensitive procedure for the rapid determination of arsenic(III) by flow injection analysis and chemiluminescence detection

A flow-injection system for determination of acetic acid in Escherichia coli cultivations with electrochemical detection based on immobilized acetate kinase (AK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) was developed to cope with the problems related to measurements under process conditions such as interferences from pyruvate, drift of electrode baseline and making the cultivation medium and reagents compatible. The results obtained by flow injection analysis were compared with those obtained with an enzymatic test kit.

Detection of amino acids at conducting electroactive polymer modified electrodes using flow injection analysis. Part II. Use of microelectrodes

Ergometrine sensing in rye flour by a magnetic bead-based immunoassay followed by flow injection analysis with amperometric detection

Dispersion in cylindrical channels on the laminar flow at low Fourier numbers

Determination of complexing abilities of ligands for metal ions by flow injection analysis and high-performance liquid chromatography : I. Principle of the substitution reaction method