University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Ari Ivaska

Abbrev:
Ivaska, A.
Other Names:
Address:
Abo Akademi University Process Chemistry Group, c/o Laboratory of Analytical Chemistry, Biskopsgatan 8, FIN 20500 Turku-Abo, Finland
Phone:
+358-2-2154420
Fax:
+358-2-2154479

Citations 17

"Potentiometric Measurements In Sequential Injection Analysis Lab-on-valve (SIA-LOV) Flow-system"
Talanta 2007 Volume 71, Issue 1 Pages 160-164
Timo Kikas and Ari Ivaska

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. © 2006 Elsevier B.V. All rights reserved.

"Spectrophotometric Determination Of Iron(III) And Total Iron By Sequential Injection Analysis Technique"
Talanta 2002 Volume 58, Issue 6 Pages 1131-1137
M. Kass and A. Ivaska

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(Ill) and tiron. The absorbance of the complexes is measured spectrophotometrically at 635 nm. Oxidation of iron(H) 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(Ill) 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. (C) 2002 Elsevier Science B.V. All rights reserved.
Tiron

"The Sequential Injection System With Adsorptive Stripping Voltammetric Detection"
Talanta 2001 Volume 53, Issue 6 Pages 1211-1219
W. W. Kubiak, R. -M. Latonen and A. Ivaska

Abstract: Two sequential injection systems have been developed for adsorptive stripping voltammetric measurement. One is for substances adsorbing at mercury, e.g. riboflavin. In this case, a simple arrangement with only sample aspiration is needed. Reproducibility was 3% and detection limit 0.07 muM. The measuring system was applied to determination of riboflavin in vitamin pills and to study the photodegradation process of riboflavin in aqueous solutions. In the second case, metal ions were determined. They have to be complexed before deposition on the mercury surface. Thus, both the sample and the ligand have to be aspirated in the system. In this case, the reproducibility was approximate to 6% and the detection limit < 0.1 ppm for cadmium, lead and copper when complexation with oxine was used. Dimethylglyoxime was used in determination of nickel and cobalt and nioxime complexes were used in determination of nickel and copper. With these complexing agents, the reproducibility was the same as with oxine, but the metals could be determined at concentrations lower than 0.01 ppm. Application of two ligands in a SIA system with AdSV detection was also studied. Simultaneous determination of copper, lead, cadmium and cobalt was possible by using oxine and dimethylglyoxime. Copper and nickel were simultaneously determined by using dimethylglyoxime and nioxime. <(c)> 2001 Elsevier Science B.V. All rights reserved.

"Interferences In A Polypyrrole-based Amperometric Ammonia Sensor"
Talanta 2000 Volume 52, Issue 2 Pages 269-275
Ilkka L&auml;hdesm&auml;ki, Wladyslaw W. Kubiak, Andrzej Lewenstam and Ari Ivaska

Abstract: The main focus of this article is on the interferences encountered when an amperometric ammonia sensor is used in matrices that are typical in clinical samples. The sensor is tested in presence of such interferences and ways to suppress them by sensor modification are presented. Two modification procedures are evaluated by comparing the stabilities, detection limits and signal-to-noise ratios of such sensors. Further, the issue of the ammonia-sensing mechanism of the polypyrrole electrode is addressed. Evidence is shown that a mobile counterion may be required for proper sensor operation. Such evidence supports the idea that polypyrrole undergoes a reversible redox,reaction when ammonia is detected at submillimolar concentrations.
Detector

"Titration Of Strong And Weak Acids By Sequential Injection Analysis Technique"
Talanta 2000 Volume 52, Issue 1 Pages 91-99
Silla Maskula, Johan Nyman and Ari Ivaska

Abstract: A sequential injection analysis (SIA) titration method has been developed for acid-base titrations. Strong and weak acids in different concentration ranges have been titrated with a strong base. The method is based on sequential aspiration of an acidic sample zone and only one zone of the base into a carrier stream of distilled water. On their way to the detector, the sample and the reagent zones are partially mixed due to the dispersion and thereby the base is partially neutralised by the acid. The base zone contains the indicator. An LED-spectrophotometer is used as detector. It senses the color of the unneutralised base and the signal is recorded as a typical SIA peak. The peak area of the unreacted base was found to be proportional to the logarithm of the acid concentration. Calibration curves with good linearity were obtained for a strong acid in the concentration ranges of 10^-4-10^-2 and 0.1-3 M. Automatic sample dilution was implemented when sulphuric acid at concentration of 6-13 M was titrated. For a weak acid, i.e. acetic acid, a linear calibration curve was obtained in the range of 3 x 10^-4-8 x 10^-2 M. By changing the volumes of the injected sample and the reagent, different acids as well as different concentration ranges of the acids can be titrated without any other adjustments in the SIA manifold or the titration protocol.

"Application Of Sequential Injection Analysis To Anodic-stripping Voltammetry"
Talanta 1997 Volume 44, Issue 4 Pages 713-723
Ari Ivaskaa,* and Wladyslaw W. Kubiakb

Abstract: The system (diagram given) incorporated an eight-port value, PVC tubing (0.8 mm i.d.), holding and auxiliary coils (1.5 m), and a thin-layer detector cell with a vitreous-C working electrode, Ag/AgCl/3 M NaCl reference electrode and stainless-steel auxiliary electrode. Successive aspiration of stripping solution, deaerated 0.1 M HCl, sample, plating solution (10 µM-HgSO4 in 0.1 M HCl) and deaerated 0.1 M HCl was performed with the potential held at +0.5 V. Solutions stacked in the holding coil were pumped to the detector in reverse sequence. The generation of the Hg film on the electrode was followed by deposition of sample at -1 V, scanning to 0 V at 20 mV/s and measurement of the stripping current. Separation of Cd(II) and In(III) was achieved using 0.01 M EDTA in 2 M NaOH as stripping solution. Separation of Cd(II) and Tl(I) was achieved using 2 M ethylenediamine in 0.1 M HCl as stripping solution. Separation of Pb(II), Cd(II), Tl(I), Cu(II) and Sn(II) was achieved using a stripping solution giving 0.04 M EDTA, 0.8 M ethylenediamine in 0.8 M NH3 buffer of pH 9.8 at the detector. The calibration graph was linear for 30-175 nM-Pb in water and the detection limit was 25 nM. 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 online 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. (C) 1997 Elsevier Science B.V.
Lead(2+) Cadmium(2+) Thallium(I) Copper(II) Tin(II) Water Voltammetry Electrode Sequential injection Buffer

"A Polypyrrole-based Amperometric Ammonia Sensor"
Talanta 1996 Volume 43, Issue 1 Pages 125-134
Ilkka L&auml;hdesm&auml;kia, Andrzej Lewenstama and Ari Ivaskaa,*

Abstract: The Pt working electrode (0.16 mm2) was coated with oxidized poly(pyrrole) electrochemically. The electrode was mounted in a wall-jet cell in a flow injection system. Samples (0.1 ml) were injected into a water carrier (1.15 ml/min) which was mixed with 50 mM borax buffer of pH 9.2 to keep the NH3/NH4 ratio constant (also pumped at 1.15 ml/min). The NH3 was detected amperometrically at 0.3 V vs. Ag/AgCl, with a graphite counter electrode. Calibration graphs were linear for 10^-100 µM-NH4Cl injected, with an RSD of 2.2% at 10 µM and 1.1% at 100 µM (n = 10). Small amounts of anions like chloride and nitrate also gave a response due to their doping effect in the polymer. The interference could be partly overcome by adding SDS and 'swamping' amounts of NaCl to the buffer stream. The sensor was partly deactivated in the presence of >1 mM NH3.
Ammonia Electrode Amperometry Sensor Interferences

"Potentiometric And Spectrophotometric Determination Of Calcium In The Wet End Of Paper Machines By Flow Injection Analysis"
Talanta 1993 Volume 40, Issue 1 Pages 95-99
Johan Nyman and Ari Ivaska*

Abstract: Paper machine back water was acidified to pH 4 with HCl (before or after filtering), injected into a stream of water at 0.5 mL min-1 and merged with 0.02 M quinolin-8-ol (0.9 mL min-1) buffered with 2-amino-2-methylpropan-1-ol to pH 10.5, which acted as a masking agent for Mg2+. After passing through a reaction coil (30 cm x 0.5 mm) the stream was treated with 0.15 mM o-cresolphthalein complexon solution (2.4 mL min-1) in a second coil and the absorbance of the solution was measured at 570 nm. The calibration graph was rectilinear in the range 10 to 250 ppm of Ca2+. For the potentiometric determination, the sample (20 µL) was injected into water as above and merged with a stream of 0.28 M NaNO3 at 0.5 mL min-1. After passage through a reaction coil (90 cm x 0.5 mm) the Ca2+ in the solution was measured with a flow-through ion-selective electrode vs. Ag - AgCl. The response was rectilinear in the range 10 to 300 ppm. The spectrophotometric method gave Ca values slightly higher than those of the potentiometric method.
Calcium Industrial Potentiometry Spectrophotometry 8-Hydroxyquinoline

"Process Analytical Chemistry - A New Direction In Analytical Chemistry"
Kem. Kemi 1988 Volume 15, Issue 5 Pages 465-468
Ivaska, A.

Abstract: The applications are discussed of process analytical chemistry in the chemical industry, particularly in the development of sensing devices capable of measuring concentration. of species directly in the process. Knowledge obtained in process analytical chemistry can also be applied where continuous monitoring and a feedback control system are used.
Closed loop Process control Review

"Flow Injection Analysis. A Dynamic Method Of Analysis"
Kem. Kemi 1986 Volume 13, Issue 5 Pages 494-499
Ivaska, A.

Abstract: The principles of flow injection analysis are reviewed. (23 references).
Review

"Voltammetric On-line Analysis Of Molecules Of Biological Importance"
J. Electroanal. Chem. 1981 Volume 128, Issue 1 Pages 459-467
W. Franklin Smyth, A. Ivaska, J.S. Burmicz, I.E. Davidson and Y. Vaneesorn

Abstract: The on-line voltammetric behavior of several groups of biologically important molecules, (a) 1,4-benzodiazepines, (b) 2-thiobarbituric acids and (c) thioamides, is investigated. A flow through voltammetric cell based on the wall jet principle is described and the DC and pulse working modes are studied in on-line situations. Direct oxidation at the glassy carbon electrode, direct oxidation at a mercury coated glassy carbon electrode and cathodic stripping on this mercury coated glassy carbon electrode have been evaluated with respect to analytical optimization, i.e., in terms of linear range, limit of detection etc.
Thioamides Benzodiazepine, derivatives Thiobarbituric acid Voltammetry Electrode Detector Flowcell

"Application Of A Voltammetric Flow-through Cell To Flow-injection Analysis (FIA)"
Collect. Czech. Chem. Commun. 1981 Volume 46, Issue 11 Pages 2865-2870
Ari Ivaskaa and Tom H. Ryan

Abstract: A new voltammetric flow-through cell has been designed to be used as an electrochemical detector in HPLC (high performance liquid chromatography) and may also be used as a voltammetric detector of FIA (flow-injection-analysis). The cell is of wall jet type and has a volume of approximately 1 µL. Performance of the cell was tested and the flow-characteristic determined by analyzing paracetamol which is oxidized at a glassy carbon electrode and is frequently used as a pain-killing drug. Application of DC (direct current) and NP (normal pulse) voltammetric working modes in FIA were studied. DC was found to be more sensitive and should be used when low sample concentrations are determined. NP was, however, found to give more reproducible results at high concentrations. A known tablet formulation containing paracetamol was analyzed by the proposed method and a good agreement was found between the result obtained and the manufacturer's certificate.
Acetaminophen Acetaminophen Anilide Hydroxyacetanilide Pharmaceutical Voltammetry Electrode Electrode Electrode Review Theory Interferences

"A Jet Ring Cell With A Renewable Solid Support For Amperometric Detection Of Glucose In A Sequential Injection Analysis System"
Anal. Lett. 1996 Volume 29, Issue 13 Pages 2257-2267
Tom Lindfors; Ilkka L&auml;hdesm&auml;ki; Ari Ivaska

Abstract: A new amperometric method for the detection of glucose has been developed. A jet ring cell with a renewable solid support (JRR) is connected to a sequential injection analysis (SIA) system. The solid support, consisting of small spherical particles of agarose gel, with a mean bead size of 90 b.mum, is coupled with the enzyme glucose oxidase (GOD). The suspension is injected through a multiport valve in the SIA-system and is trapped in the JRR cell by a gap of 10 b.mum between the glassy carbon (GC) working electrode and a stainless steel counter electrode. The subsequent injection of glucose results in formation of hydrogen peroxide, which is detected by oxidation at 1.0 V (vs. Ag/AgCl/KCl (3 M)). Thereafter the suspension is removed by reversing the pump flow and subsequently replaced with fresh suspension for the next determination of glucose. The linear working range for the JRR-sensor, at this stage of the work, is 100 b.muM - 5 mM.
Glucose Amperometry Sequential injection Interferences Jet ring cell

"Spectrophotometric Determination Of Sulphur Dioxide And Hydrogen Sulfide In Gas Phase By Sequential Injection Analysis Technique"
Anal. Chim. Acta 2001 Volume 449, Issue 1-2 Pages 189-197
M. Kass and A. Ivaska

Abstract: Methods for determination of H2S and SO2 in gas phase have been developed. The methods are based on absorption of the gases in scrubbing solutions and subsequent sequential injection analysis (SIA) determination of the absorbed gases. The reagents used in the SIA measurements, pararosaniline for SO2 and nitroprusside for H2S, are very specific for the analytes. Absorbance of the reaction products is measured at 558 nm. The methods have been developed for determination Of SO2 in the range 1.6-8.0 g/m(3) and H2S in the range 5-15 g/m(3). The relative standard deviation of the determinations is less than 2.5% (n = 10). The methods developed are intended for on-line monitoring of H2fS and SO2 in gas generated when heating coal at coke production.

"Spectrophotometric Determination Of Calcium In Paper Machine White Water By Sequential Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 286-292
Johan Nyman and Ari Ivaska*

Abstract: The determination of Ca in white water of a paper machine was based on the formation of the colored complex between Ca2+ and o-cresolphthalein complexone (CPC). White water samples were centrifuged at 1500 rpm for 30 min and the clear supernatant solution was used for the Ca2+ determination. The analysis was carried out on a computer-controlled sequential analysis system comprising of a peristaltic pump, a 10 port multi-position valve, a holding coil (1.5 m x 0.9 mm i.d.), a reaction coil (60 cm x 0.5 mm i.d.) and a spectrophotometric detector equipped with a sandwich-type flow-through cell (30 µL; 3 mm light path). The detection wavelength was 580 nm and flow-rates of 3.3-3.5 ml/min were used. The analysis was carried out by aspirating sample solution from the holding coil for 0.5 s (30 µL) followed by 2.5 mg/ml 8-hydroxquinoline solution for 1 s (60 µL) and 0.24 mM CPC for 1 s (60 µL). The mixture was pumped through the detection cell. The calibration graph was linear for 10^-500 mg/l Ca and the RSD (n = 5) was 2.5% within the linear range.
Calcium Process liquor Water Spectrophotometry Sequential injection Complexation Computer

"A Computer-controlled Voltammetric Flow Injection System"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 433-438
Mikael Wasberg and Ari Ivaska

Abstract: The cited system is described and illustrated and is demonstrated by the determination of I- and Cl-. Sequential change of the sampling channel allows injections from various flows into the carrier stream that can easily be changed for special plating or washing procedures and the valve system permits the introduction of up to three more flow streams. In the determination of I-, rectilinear response is achieved between 0.04 and 0.4 mM with coefficient of variation of 3.0 and 0.6% at the lower and upper ends of the range, respectively.
Chloride Iodide Electrode Voltammetry Computer Theory

"Applications Of A Voltammetric Flow-through Cell In Online Analysis For Organic Compounds"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 283-291
Ari Ivaska, W. Franklin Smyth

Abstract: A flow-through voltammetric cell is described and the DC and pulse working modes are studied in on-line situations. On-line analysis of different compounds has been done by (a) direct oxidation at a glassy carbon electrode, (b) direct reduction or (c) direct oxidation at a mercury-coated solid electrode, and (d) cathodic stripping by first depos-iting the compound on a mercury film and then employing a cathodic DC voltage scan. The linear range and the detection limit of the on-line method are better than those in quiescent solutions
Organic compounds Electrode Voltammetry Flowcell