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Jacobus F. Van Staden - One of the best experts on this subject based on the ideXlab platform.
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Application of phthalocyanines in flow- and Sequential-Injection Analysis and microfluidics systems: A review
Talanta, 2015Co-Authors: Jacobus F. Van StadenAbstract:Phthalocyanines and metallophthalocyanines play a very important role in the metabolism of living organisms through biological pigments or biochromes and are therefore also employed in numerous applications in analytical chemistry. In flow-, and Sequential-Injection Analysis and microfluidic systems the role of phthalocyanines and metallophthalocyanines is centered as either that of analyte or that of a reagent or modifier in the determination of other species. This paper covers the attributes of phthalocyanines and metallophthalocyanines complexes as enhancements in chemical Analysis in flow- and Sequential Injection Analysis and microfluidic systems and points out the advantages and disadvantages in the implementation thereof.
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Simultaneous Determination of L- and D-T4 Using a Sequential Injection Analysis/Sensors System
Combinatorial chemistry & high throughput screening, 2010Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel BalcuAbstract:A Sequential Injection Analysis system was selected for the simultaneous determination of L- and D-T4 in raw material and pharmaceutical products, because of the highest precision and accuracy, the lower consumption of sample and buffer, and the flexibility of selecting different buffers accordingly with the type of sensors utilized as detectors. An amperometric biosensor based on D-amino acid oxidase was used as detector for D-T4 and an immunosensor based on anti-L-T4 was used as detector for L-T4. The SIA/biosensors system can be used reliably on-line in synthesis process control, for the simultaneous assay of L- and D- T4 with a frequency of more than 30 samples per hour.
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Determination of Free L-T4 and Free L-T3 from Blood Using the Immunosensors/Sequential Injection Analysis System
Analytical Letters, 2010Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel Balcu, Marius Constantin Mirica, Gabriel Lucian RaduAbstract:An immunosensors/Sequential Injection Analysis system is proposed for the assay of thyroid hormones free L-T4 and free L-T3 in blood samples. The working concentration ranges for free L-T4 and free L-T3, are between 2.0 and 720.0 pmol/L and between 2.0 and 340.0 pmol/L, respectively, with detection limits of 1.0 and 1.7 pmol/L, respectively. The selectivity of the immunosensors, as well as the recovery tests done for free L-T4 and free L-T3 (99.90 ± 0.01% (n = 10) and 99.94 ± 0.02% (n = 10)), made the immunosensors/Sequential Injection Analysis system suitable for the direct assay of thyroid hormones in blood samples.
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Determination of (+)-3,3',5,5'-Tetraiodo-L-thyronine (L-T4) in Serum and pharmaceutical formulations using a Sequential Injection Analysis/immunosensor system.
Journal of immunoassay & immunochemistry, 2008Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel Balcu, Marius Constantin Mirica, Nicolae MiricaAbstract:A Sequential Injection Analysis/immunosensor system is proposed for the Analysis of thyroxine (L-T4) in serum and in pharmaceutical formulations with a rate of 75 samples/hour. The immunosensor design is based on the physical immobilization of anti-L-T4 in carbon paste. The working concentration range of the immunosensor in the Sequential Injection Analysis system is between 36 and 1080 ng/mL with a limit of detection of 24.6 ng/mL. The system is very reliable and very easy to design and operate.
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On-line assay of the S-enantiomers of enalapril, ramipril and pentopril using a Sequential Injection Analysis/amperometric biosensor system.
Journal of pharmaceutical and biomedical analysis, 2004Co-Authors: Raluca-ioana Stefan, Jacobus F. Van Staden, Camelia Bala, Hassan Y. Aboul-eneinAbstract:A Sequential Injection Analysis/amperometric biosensor system is proposed for the enantioselective Analysis of the S-enantiomer of enalapril, ramipril and pentopril. The amperometric biosensor used as detector in the Sequential Injection Analysis was designed by immobilization of l-amino acid oxidase in carbon paste. The proposed SIA system can be utilized reliably for the enantioAnalysis of the S-enantiomer from the raw materials as well as from their pharmaceutical formulations, with a rate of 75 samples per hour and R.S.D. values better than 0.1% (n = 10).
Hassan Y. Aboul-enein - One of the best experts on this subject based on the ideXlab platform.
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Simultaneous Determination of L- and D-T4 Using a Sequential Injection Analysis/Sensors System
Combinatorial chemistry & high throughput screening, 2010Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel BalcuAbstract:A Sequential Injection Analysis system was selected for the simultaneous determination of L- and D-T4 in raw material and pharmaceutical products, because of the highest precision and accuracy, the lower consumption of sample and buffer, and the flexibility of selecting different buffers accordingly with the type of sensors utilized as detectors. An amperometric biosensor based on D-amino acid oxidase was used as detector for D-T4 and an immunosensor based on anti-L-T4 was used as detector for L-T4. The SIA/biosensors system can be used reliably on-line in synthesis process control, for the simultaneous assay of L- and D- T4 with a frequency of more than 30 samples per hour.
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Determination of Free L-T4 and Free L-T3 from Blood Using the Immunosensors/Sequential Injection Analysis System
Analytical Letters, 2010Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel Balcu, Marius Constantin Mirica, Gabriel Lucian RaduAbstract:An immunosensors/Sequential Injection Analysis system is proposed for the assay of thyroid hormones free L-T4 and free L-T3 in blood samples. The working concentration ranges for free L-T4 and free L-T3, are between 2.0 and 720.0 pmol/L and between 2.0 and 340.0 pmol/L, respectively, with detection limits of 1.0 and 1.7 pmol/L, respectively. The selectivity of the immunosensors, as well as the recovery tests done for free L-T4 and free L-T3 (99.90 ± 0.01% (n = 10) and 99.94 ± 0.02% (n = 10)), made the immunosensors/Sequential Injection Analysis system suitable for the direct assay of thyroid hormones in blood samples.
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Determination of (+)-3,3',5,5'-Tetraiodo-L-thyronine (L-T4) in Serum and pharmaceutical formulations using a Sequential Injection Analysis/immunosensor system.
Journal of immunoassay & immunochemistry, 2008Co-Authors: Raluca-ioana Stefan-van Staden, Jacobus F. Van Staden, Hassan Y. Aboul-enein, Ionel Balcu, Marius Constantin Mirica, Nicolae MiricaAbstract:A Sequential Injection Analysis/immunosensor system is proposed for the Analysis of thyroxine (L-T4) in serum and in pharmaceutical formulations with a rate of 75 samples/hour. The immunosensor design is based on the physical immobilization of anti-L-T4 in carbon paste. The working concentration range of the immunosensor in the Sequential Injection Analysis system is between 36 and 1080 ng/mL with a limit of detection of 24.6 ng/mL. The system is very reliable and very easy to design and operate.
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On-line assay of the S-enantiomers of enalapril, ramipril and pentopril using a Sequential Injection Analysis/amperometric biosensor system.
Journal of pharmaceutical and biomedical analysis, 2004Co-Authors: Raluca-ioana Stefan, Jacobus F. Van Staden, Camelia Bala, Hassan Y. Aboul-eneinAbstract:A Sequential Injection Analysis/amperometric biosensor system is proposed for the enantioselective Analysis of the S-enantiomer of enalapril, ramipril and pentopril. The amperometric biosensor used as detector in the Sequential Injection Analysis was designed by immobilization of l-amino acid oxidase in carbon paste. The proposed SIA system can be utilized reliably for the enantioAnalysis of the S-enantiomer from the raw materials as well as from their pharmaceutical formulations, with a rate of 75 samples per hour and R.S.D. values better than 0.1% (n = 10).
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Determination of (+)-3,3',5-triiodo-L-thyronine (L-T3) from serum using a Sequential Injection Analysis/immunosensor system.
Journal of immunoassay & immunochemistry, 2004Co-Authors: Raluca-ioana Stefan, Jacobus F. Van Staden, Hassan Y. Aboul-eneinAbstract:Abstract A Sequential Injection Analysis/immunosensor system is proposed for the Analysis of T3 in serum with a rate of 75 samples/hr. The immunosensor design is based on the physical immobilization of anti‐T3 in carbon paste. The working concentration range of the immunosensor in a Sequential Injection Analysis system is between 3.4 and 340 ng/mL with a limit of detection of 2.19 ng/mL. The system is very reliable and very easy to design and operate.
Víctor Cerdà - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of sorbitol in Pichia pastoris cultivation applying Sequential Injection Analysis
Biochemical Engineering Journal, 2008Co-Authors: Burkhard Horstkotte, Francisco Valero, Carolina Arnau, Olaf Elsholz, Víctor CerdàAbstract:Abstract A simple and robust analyser system based on Sequential Injection Analysis for the determination of sorbitol in Pichia pastoris MutS phenotype batch fermentation is described. Applicability for the bioprocess monitoring of sorbitol in batch culture medium in a concentration range of 8–1.5 g l−1 with satisfying sorbitol recovery was demonstrated during 60 h. Optimization of physical and chemical parameters is further described. The method proved to be reproducible (R.S.D.
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At-line determination of formaldehyde in bioprocesses by Sequential Injection Analysis
Analytica Chimica Acta, 2006Co-Authors: Burkhard Horstkotte, Víctor Cerdà, Olaf Elsholz, E. Werner, Stefan Wiedemeier, Reiner LuttmannAbstract:Abstract A Sequential Injection Analysis (SIA) method for the at-line determination of formaldehyde in a cultivation process of Pichia pastoris is presented. A genetically modified yeast strain was used for cultivation processes wherein methanol feed induced the production of the recombinant protein 1-3del I-TAC. Recurring measurements of culture medium, its blank and including standard addition were performed with Nash reagent using an automated syringe device and photometric detection. The apparatus was coupled via a laboratory-made flow-through adapter to a continuous filtered and cell-medium flow from the bioreactor. At-line monitoring of formaldehyde was performed at two cultivations, each of 250 h during fed-batch phases with glycerol and methanol as carbon sources. High reliability, robustness and reproducibility of the method, the software and the instrumentation as well as the high selectivity of the reaction were demonstrated.
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Spectrofluorimetric determination of aluminum in drinking waters by Sequential Injection Analysis
Analytica Chimica Acta, 2002Co-Authors: Christophe Brach-papa, Víctor Cerdà, Bruno Coulomb, Jean-luc Boudenne, Frédéric ThéraulazAbstract:Abstract A selective procedure for the determination of Al 3+ in drinking and natural waters is proposed. The analytical procedure is based both on the complex formation between Al 3+ and 8-hydroxyquinoline-5-sulfonic acid (HQS) and on a fluorimetric detection of the complex. The reaction was carried out in presence of thioglycolic acid as a masking agent. This procedure has been adapted to a Sequential Injection Analysis (SIA) system. Operative conditions both for batch and SIA procedures were investigated including reagent concentration, volumes, pH and wavelengths used for the fluorimetric detection. Batch procedure allows determination of Al 3+ at ppb level (LOQ: 2.8 μg l −1 ) within a working range of 2.2–300 μg l −1 . The SIA procedure was successfully employed for the determination of Al 3+ in several commercial drinking and tap waters.
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Monitoring of environmental parameters by Sequential Injection Analysis
Trends in Analytical Chemistry, 2001Co-Authors: Víctor Cerdà, F Bauzá, Andreu Cladera, Artemi Cerda, Rosanna Forteza, Manuel Miró, E Gomez, José Manuel EstelaAbstract:The use of Sequential Injection Analysis (SIA), as applied to the control of environmental parameters, is reviewed. Its advantages and drawbacks are compared with those of flow Injection Analysis (FIA). FIA is simpler and easier to handle, has a higher sample throughput, and may be controlled manually, but SIA is more robust and versatile and better adapted for multiparametric and stopped flow techniques.
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Study on the implementation of flow titrations in Sequential Injection Analysis
Laboratory Robotics and Automation, 1999Co-Authors: J.m. Estela, Andreu Cladera, F. Más, Víctor CerdàAbstract:Several variables that affect flow spectrophotometric titrations in Sequential Injection Analysis (SIA) systems were studied by using titration of a strong acid with a strong base as a model; blue bromothymol was used as an indicator and distilled water was used as a carrier. Both possibilities of performing titrations on SIA systems according to the aspiration sequences (a) titrant B/sample/titrant A and (b) titrant/sample are considered. In case (a) the possibilities regarding the use of different volumes and/or different concentrations of titrant reagents were studied and are discussed. The established methodology allows hydrochloric acid determinations with 0.1 M sodium hydroxide within the range 32–1000 mM by means of logarithmic calibration curves. The Analysis rate is of 5 min/sample. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 207–216, 1999
Ari Ivaska - One of the best experts on this subject based on the ideXlab platform.
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Potentiometric measurements in Sequential Injection Analysis lab-on-valve (SIA-LOV) flow-system.
Talanta, 2006Co-Authors: Timo Kikas, Ari IvaskaAbstract:Abstract Advantages of using Sequential Injection Analysis lab-on-valve (SIA-LOV) in potentiometric measurements are studied with Ca2+ sensitive solid-contact ion-selective electrodes (SC-ISE) and pH electrode based on polyaniline (PANI). Experiments show that Ca2+-SC-ISE requires a stopped flow mode to be used in order to get longer equilibration time. On the other hand, PANI based pH electrode gives better results under flow conditions. SIA-LOV was found to be a flexible solution handling system for potentiometric measurements. The technique gives a possibility to fine-tune the calibration range or even recondition the electrode before every measurement without losing in linear range of calibration.
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Spectrophotometric determination of iron(III) and total iron by Sequential Injection Analysis technique
Talanta, 2002Co-Authors: M Kass, Ari IvaskaAbstract:Abstract A procedure for determination of concentrations of iron(III) and total iron by Sequential Injection Analysis is described. The method is based on the strong blue-colored complexes formed between iron(III) and tiron. The absorbance of the complexes is measured spectrophotometrically at 635 nm. Oxidation of iron(II) and masking of interfering fluoride is simultaneously done by injecting one zone of hydrogen peroxide and one of thorium(IV) between the sample and reagent zones. Concentration of iron(III) and total iron, in the range 0.002–0.026 M, in diluted samples from a pickle bath were determined. The relative standard deviation was 0.4% (n=7). The method was also used in a pilot plant of a zinc process for determination of iron(III) in the range 0.2–3.0 g l−1. The sample throughput is approximately 17 samples per hour, including three repetitive determinations of each sample.
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Application of Sequential Injection Analysis to anodic stripping voltammetry
Talanta, 1997Co-Authors: Ari Ivaska, Władysław W. KubiakAbstract:Sequential Injection Analysis (SIA) technique has been applied to anodic stripping voltammetry (ASV). The sample and reagent volumes can easily be controlled by SIA. The technique also allows plating of the mercury film on-line and therefore substantially reduces generation of mercury containing waste. Repeated sample passage through the detector was used during the deposition step to enhance the sensitivity. The way solution handling is done in SIA allows an easy and effective medium exchange procedure increasing the selectivity of the method. This has been demonstrated by changing the stripping medium and having different complexing agents in the stripping solution. The observed potential shifts of the stripping peaks could theoretically be explained in the cases where the complexation constants are known. Calibration and the standard addition methods are discussed and demonstrated by determining copper in tap water as a method of testing the procedure.
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Spectrophotometric determination of calcium in paper machine white water by Sequential Injection Analysis
Analytica Chimica Acta, 1995Co-Authors: Johan O. Nyman, Ari IvaskaAbstract:Abstract A Sequential Injection Analysis method is developed for the determination of calcium in white water of a paper machine. The determination is based on the formation of a coloured complex between Ca 2+ and o -cresolphthalein complexone, which is monitored spectrophotometrically. Parameters of the method were optimized in order to give a working range as broad as possible. A working range of 5–500 mg l −1 Ca 2+ was achieved with a sample volume of 30 μ1. Preliminary tests of the method were conducted using off-line samples from different paper mills in Finland. The method developed was also tested in an on-line application at a paper mill which produces wood-containing paper grades.
J.f. Van Staden - One of the best experts on this subject based on the ideXlab platform.
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Speciation of Mn(II) and Mn(VII) by on-line spectrophotometric Sequential Injection Analysis
Analytica Chimica Acta, 2003Co-Authors: J.f. Van Staden, L.v Mulaudzi, Raluca-ioana StefanAbstract:An on-line Sequential Injection Analysis system with spectrophotometric detection using 4-(2-pyridylazo) resorcinol as reagent is proposed for the speciation of Mn(II) and Mn(VII). The sampling frequency is 30 determinations per hour. The linear range for Mn(II) is 0.020–0.500 mg/l with a detection limit of 0.005 mg/l and for total Mn 0.025–0.550 mg/l with a detection limit of 0.008 mg/l. The % RSD is 0.27 and 0.34 for Mn(II) and Mn(VII), respectively (n = 10). Chemical masking of Fe and Al was achieved by on-line addition of a 0.1 mol/l NaF solution. The proposed system yielded results that compare very well with standard methods. © 2003 Elsevier B.V. All rights reserved.
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Simultaneous detection of S and R captopril using Sequential Injection Analysis.
Talanta, 2000Co-Authors: Raluca-ioana Stefan, J.f. Van Staden, Hassan Y. Aboul-eneinAbstract:A simultaneous detection Sequential Injection Analysis (SIA) system is proposed for the determination of S and R captopril using a potentiometric, enantioselective membrane electrode based on maltodextrin (DE=14–17) for the assay of S-captopril and an amperometric biosensor for the assay of R-captopril. The proposed SIA system can be utilized reliably for the on-line simultaneous detection of the enantiomers in the synthesis process at a rate of 38 samples per hour in the following linear concentration ranges: 100–1000 nmol/l (R-captopril) and 1–1000 μmol/l (S-captopril) with a RSD better than 0.009% (n=10).
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spectrophotometric determination of thiocyanate by Sequential Injection Analysis
Analytica Chimica Acta, 2000Co-Authors: J.f. Van Staden, Anna-maria BothaAbstract:A Sequential Injection Analysis (SIA) system was developed for the spectrophotometric determination of thiocyanate as Fe(SCN) 2C . The physical parameters (flow rate, sample and reagent volumes, holding coil and reaction coil internal diameter and length) which influence dispersion in a SIA system were optimized. The effect of the reagent concentration and nitric acid concentration (in the reagent solution and carrier stream, respectively), were also studied. Reagent consumption was effectively reduced by introducing the reagent as a zone into the nitric acid carrier stream, compared to flow Injection Analysis where the reagent itself is the carrier stream. The system is fully computerized and able to monitor thiocyanate in samples at 24 samples per hour with a relative standard deviation of <1.20% for samples and standards with thiocyanate concentrations above 10.0 mg l 1 . The calibration graph is linear from 2.0 to 150.0 mg l 1 with a 3 detection limit of 1.1 mg l 1 . The system has been applied to the determination of thiocyanate in process solutions and waste waters. ©2000 Elsevier Science B.V. All rights reserved.
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Spectrophotometric determination of thiocyanate by Sequential Injection Analysis
Analytica Chimica Acta, 2000Co-Authors: J.f. Van Staden, Anna-maria BothaAbstract:A Sequential Injection Analysis (SIA) system was developed for the spectrophotometric determination of thiocyanate as Fe(SCN) 2C . The physical parameters (flow rate, sample and reagent volumes, holding coil and reaction coil internal diameter and length) which influence dispersion in a SIA system were optimized. The effect of the reagent concentration and nitric acid concentration (in the reagent solution and carrier stream, respectively), were also studied. Reagent consumption was effectively reduced by introducing the reagent as a zone into the nitric acid carrier stream, compared to flow Injection Analysis where the reagent itself is the carrier stream. The system is fully computerized and able to monitor thiocyanate in samples at 24 samples per hour with a relative standard deviation of
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Determination of Reaction Stoichiometries by Using the Sequential Injection Analysis Technique
Instrumentation Science & Technology, 1999Co-Authors: J.f. Van Staden, H. Du Plessis, R.e. TaljaardAbstract:Abstract A simple and reliable Sequential Injection Analysis system is proposed to determine the reaction stoichiometries of different complexes. In this study, the Fe(III)/Tiron complex as 1:1 complex and the Fe(II)/1,10-phenanthroline complex as 1:3 complex were evaluated. The importance of the correct reagent order, as well as the need for thorough mixing, is highlighted.
