University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Ivano G.R. Gutz

Abbrev:
Gutz, I.G.R.
Other Names:
Ivano Gebhardt Rolf Gutz
Address:
Instituto de Quimica, Universidade de Sao Paulo, Av. Prof. Lineu de Prestes, 748, 05508-900 Sao Paulo, Brazil
Phone:
+55-19-429-2150
Fax:
+55-11-3091-2150

Citations 19

"Microfluidic Cells With Interdigitated Array Gold Electrodes: Fabrication And Electrochemical Characterization"
Talanta 2005 Volume 68, Issue 2 Pages 429-436
Daniela Daniel and Ivano G.R. Gutz

Abstract: Microfluidic flow cells combined with an interdigitated array (IDA) electrode and/or individually driven interdigitated electrodes were fabricated and characterized for application as detectors for flow injection analysis. The gold electrodes were produced by a process involving heat transfer of a toner mask onto the gold surface of a CD-R and etching of the toner-free gold region by short exposure to iodine-iodide solution. The arrays of electrodes with individual area of 0.01 cm2 (0.10 cm of length x 0.10 cm of width and separated by gaps of 0.05 or 0.03 cm) were assembled in microfluidic flow cells with 13 or 19 ?m channel depth. The electrochemical characterization of the cells was made by voltammetry under stationary conditions and the influence of experimental parameters related to geometry of the channels and electrodes were studied by using K4Fe(CN) 6 as model system. The obtained results for peaks currents (I p) are in excellent agreement with the expected ones for a reversible redox system under stationary thin-layer conditions. Two different configurations of the working electrodes, Ei, auxiliary electrode, A, and reference electrode, R, on the chip were examined: Ei/R/A and R/Ei/A, with the first presenting certain uncompensated resistance. This is because the potentiostat actively compensates the iR drop occurring in the electrolyte thin layer between A and R, but not from R to each E i. This is confirmed by the smaller difference between the cathodic and anodic peak potentials for the second configuration. Evaluation of the microfluidic flow cells combined with (individually driven) interdigitated array electrodes as biamperometric or amperometric detectors for FIA reveals stable and reproducible operation, with peak heights presenting relative standard deviations of less than 2.2%. For electrochemically reversible species, FIA peaks with enhanced current signal were obtained due to redox cycling under flow operation. The versatility of microfluidic flow cells, produced by simple and low-cost technique, associated with the rich information content of electrochemical techniques with arrays of electrodes, opens many future research and application opportunities. © 2005 Elsevier B.V. All rights reserved.

"Ultra-simple Adaptor To Convert Batch Cells With Mercury Drop Electrodes In Voltammetric Detectors For Flow Analysis"
Talanta 2003 Volume 60, Issue 4 Pages 695-705
Jairo J. Pedrotti and Ivano G. R. Gutz

Abstract: A simple, robust and fast-responding flow adaptor for mercury drop electrodes (MDEs) is described. An L-shaped PTFE tube with an internal diameter of 0.5 mm is fixed with a silicone ring on the glass capillary of a MDE, in such a way as to direct the outcoming flow onto the mercury drop, from a distance of about 0.5 mm. Any commercial or laboratory-made batch cell, provided with an MDE, serves for the purpose. The level of supporting electrolyte in the cell is maintained constant through a siphon or a lateral draining orifice. The adaptor is compatible with all the different brands and operating modes of the MDEs (free dropping, controlled drop time, renewable static drop, hanging drop or sessile drop). Flow injection experiments were conducted with the following amperometric detection modes: sampled-DC, reverse pulse amperometry (RPA), and anodic stripping voltammetry (ASV). The FIA-RPA peaks presented a RSD <0.8% for 1.0 x 10^-5 mol L-1 lead(II) (N=30, V(sample)=100 µl). The response time (0-63% of the signal maximum) to a concentration step is 1.2 s for 500 µl injections of 0.1 mmol L-1 ascorbic acid in acetate buffer at a flow rate of 1 mL min-1, which corresponds to a response volume of 20 µl. As an example of practical application, copper(II) was determined in fertilizers by RPA using the standard addition method, at an analytical frequency of 90 injections per h.

"Determination Of Low Concentrations Of The Flotation Reagent Ethyl Xanthate By Sampled DC Polarography And Flow Injection With Amperometric Detection"
Talanta 2001 Volume 54, Issue 2 Pages 403-409
Pilar Hidalgo and Ivano G. R. Gutz

Abstract: A polarographic DCinst method with the static mercury drop electrode, SMDE, was developed for determination of the flotation collector ethyl xanthate (EtX) in the concentration range from 1 x 10^-5 to 8 x 10^-5 M. The potentiality of the method was demonstrated by evaluating the capacity of powdered galena ore (PbS) to adsorb EtX in a titration-like procedure. Sulfide could be determined simultaneously with EtX because in NaOH electrolyte their anodic waves are well separated (E-1/2 congruent to - 0.72 and - 0.42 V Versus Ag/AgCl, respectively). In addition, a new FIA method was developed by adapting a simple device to the tip of the glass capillary of a mercury electrode and doing amperometric detection at a fixed potential of - 0.1 V, always in the DCtast mode. No oxygen removal was required. Reproducible results were obtained at a frequency of 72 injections per h, with automatic renewal of the SMDE every second. The calibration curve for freshly prepared EtX standards rendered a straight line from 5 x 10^-6 to 8 x 10^-5 hi with correlation coefficient of 0.997, suitable for real applications in flotation processes and its effluents. (C) 2001 Elsevier Science B.V. All rights reserved.

"Pinch Valve Injector For Flow Analysis"
Quim. Nova 2001 Volume 24, Issue 5 Pages 689-692
Fabiano S. Palgrossi, Jairo J. Pedrotti# e Ivano G. R. Gutz

Abstract: An important component for the automation of flow injection analysis (FIA) systems is the sample injection valve. A simple and inexpensive commutator with 16 pinch valves (8 normally open and 8 closed) was developed and configured as a multichannel injection valve. It is activated by a single solenoid of 3 Kgf, powered by a pulsed driver circuit, controlled by a microcomputer or a switch. FIA with spcctrophometric detection of potassium dichromate solution was used for the evaluation of the new injection valve and its comparison with other valves, for sample loops of 50, 100, 200, 300 and 500 µL. The repeatability was favorable (RSD 1.0% for 15 injections at each loop volume) compared to a manual injector, an electropneumatic injector and an injector configured with three mini solenoid valves (RSD 1.1, 1.3 and 1.0%, respectively, for15 injections at each loop volume).

"Spectroelectrochemical Determination Of Chlorpromazine Hydrochloride By Flow-injection Analysis"
J. Pharm. Biomed. Anal. 2005 Volume 37, Issue 2 Pages 281-286
Daniela Daniel and Ivano G.R. Gutz

Abstract: An original, simple and sensitive flow-injection spectroelectroanalytical method for the determination of chlorpromazine in pure form or in pharmaceutical formulations is described. The method is based on the formation of a stable cationic radical by electro-oxidation in sulfuric acid medium (0.1 mol l -1), monitored in situ at ? = 524 nm. The determination of chlorpromazine hydrochloride in pure form or in pharmaceutical formulations was explored, considering the amperometric and the absorptiometric signal. The association of these two signals enhanced the selectivity of the analysis and proved decisive when other electroactive compounds or excipients like ascorbic acid were present in the formulation. The analytical parameters have been evaluated and the results obtained using standard additions are in agreement with the reference methods. © 2004 Published by Elsevier B.V.

"Fast Mapping Of Gunshot Residues By Batch Injection Analysis With Anodic Stripping Voltammetry Of Lead At The Hanging Mercury Drop Electrode"
Electroanalysis 2005 Volume 17, Issue 2 Pages 105-112
Adriana De Donato, Ivano G. R. Gutz*

Abstract: The forensic analysis of lead in gunshot residues (GSR) sampled on the hands of potential shooters is rendered faster, simpler and less expensive by a new batch injection analysis (BIA) method, based on differential pulse anodic stripping voltammetry (DPASV). A simple J shaped adaptor was designed to direct the flux of the analyte injected with a micropipettor onto the hanging mercury drop electrode of any commercial electrode stand. Sampling methods for GSR were compared and lifting with adhesive tape was elected for field use. The tapes are glued on polyethylene screens and stored in capped vials. Sampling with multiple strips provides coarse mapping of the distribution of lead on the shooter's hands. After a dissolution/extraction step with chloroform/aqueous 0.10 mol L-1 HCl, 100 L of the aqueous phase are injected during 25 s for accumulation of lead on the HMDE at -0.60 V (vs. Ag/AgCl). A detection limit of 20 ng/mL of Pb(II), outreaching for GSR analysis, is reached without oxygen removal, at a frequency of 20 injections per hour. Results for sequences of shootings with a revolver and a pistol are presented.

"Critical Comparison Of Four Simple Adaptors For Flow Amperometric And Stripping Voltammetry With Mercury Drop Electrodes In Batch Cells"
Electroanalysis 2004 Volume 16, Issue 5 Pages 391-398
Andrea Cavicchioli, Daniela Daniel, Ivano Gebhardt Rolf Gutz*

Abstract: Electrochemical batch cells with mercury drop electrodes, MDEs, are readily available from a number of producers and widely used in electroanalysis for polarography, voltammetry and stripping voltammetry. To increase sample throughput and reduce reagent and sample consumption, the tendency is to couple the MDE with flow analysis systems (e.g., FIA, SIA or BIA). Many special flow cells for MDEs are described in the literature, but it is easier to convert existing commercial batch cells to flow operation. To assess the performance of such flow adaptors, four models were chosen because they are directly fitted to the glass capillary of any MDE, light enough not to impair the mechanical drop knocker and can be effortlessly built in the laboratory. They were all found adequate for flow amperometry and stripping voltammetry, with differences in sensitivity, flow rate dependence, response time, drop stability, tolerance to bubbles, uncompensated resistance and recontamination of disposed analyte from the electrolytic bath. Two of them, a simple L-shaped PTFE tube and an upstream nozzle holder made from a disposable pipette tip, gather a larger set of desirable features.

"Long-optical-path Thin-layer Spectroelectrochemical Flow Cell With Inexpensive Gold Electrodes"
Electroanalysis 2001 Volume 13, Issue 8-9 Pages 681-685
Daniela Daniel, Ivano G. R. Gutz

Abstract: A novel long-optical-path thin-layer spectroelectrochemical cell for flow systems is described and its suitability for in situ UV-visible applications, demonstrated. Gold electrodes with flat surface are simply cut from standard recordable CDs of the gold sputtered type. After removal of the protecting polymer layer, the area of the working and auxiliary coplanar electrodes is delineated by scraping off the gold layer. A set of twin electrodes is placed face to face within any standard spectrophotometric cuvette with 1.0 cm optical path. The sample is introduced with a syringe or peristaltic pump and reaches the bottom of the working electrodes through a PTFE tube. Evaluation was done with o-tolidine in acidic medium as a model system, and gave good results under stationary conditions and in the FIA mode. The appropriateness of the tell for flow operation including FlA, good potential control, simplicity of construction and maintenance, easy adaptability to existing instrumentation and a cost lower than any other proposed model are advantages of the innovative cell design.

"Determination Of Traces Of Uranium In Environmental Samples Using A Flow Injection System With Amperometric Catalytic Detection"
Electroanalysis 2000 Volume 12, Issue 10 Pages 742-746
Marco A. S. Aguiar, Karem S. G. Marquez, Ivano G. R. Gutz

Abstract: A new method for flow injection analysis (FIA) of traces of uranium by catalytic amperometric detection in nitrate medium is described. Interfering oxygen was removed by in-line degassing. A simple adapter was designed to afford FIA with batch cells comprising a hanging mercury drop electrode. The carrier electrolyte consisted of 10 mM LiNO3 and the electrolyte for the samples was 10 mM HNO3 + 10 mM LiNO3. The method is simple, rapid (up to 60 injections/h) and precise (RSD = 1.0% for n = 10 and C-U = 80 nM), presenting a LD of 13 pg of U or 3 nM (3 SD). Dissolution of solid samples (rock and soil) was abbreviated by employing a mixture of nitric and hydrofluoric acids in microwave heated closed vessels, followed by liquid-liquid extraction with TBP. Analysis of reference materials and intercomparison with other techniques gave very favorable results.

"A Batch Injection Analysis System For Ascorbic Acid Determination Using Amperometric Detection On A Sessile Mercury Drop Electrode"
Electroanalysis 1999 Volume 11, Issue 15 Pages 1124-1129
Adriana De Donato, Jairo J. Pedrotti, Ivano G.R. Gutz

Abstract: A batch injection analysis (BIA) system, which uses an automatic mercury electrode (AME) as an amperometric detector, is described. The capillary of this AME was adapted in an inverted position through the bottom of a simple cylindrical electrochemical cell, in order to generate more stable sessile drops and to grant free access for the tip of the programmable micropipettor. The BIA system was evaluated by using the electrochemical oxidation of L-ascorbic acid to dehydroascorbic acid on the sessile mercury drop electrode. Acetate buffer solution (50 mM, pH 4.8) was used as supporting electrolyte. The working electrode was operated at +0.230 V (vs. Ag/AgCl). The effect of the dispensing rate, of the dispensed volume, of the distance between the mercury drop and the pipettor tip, as well as of the solution level in the cell were evaluated. Injections of 50 µL were suitable to reach a detection limit of about 2.5 µM (450 ppb). At the 50 µM ascorbic acid level, an RSD of 1.6% (N = 35) was observed with or without mercury drop renewal between injections. A frequency of 300 injections per hour may be reached when the drop is renewed sporadically. The new BIA method was applied to the determination of ascorbic acid in packed/canned tropical fruit juices. Selectivity was granted by differential measurements of the peak current before and after exposure of samples to ascorbate oxidase (from cucumber).
Ascorbic acid Batch injection analysis

"Miniaturized Reference Electrodes With Microporous Polymer Junctions"
Electroanalysis 1996 Volume 8, Issue 7 Pages 673-675
Jairo J. Pedrotti, L&uacute;cio Angnes, Ivano G. R. Gutz *

Abstract: The construction and evaluation of a simple and effective mini-reference electrode is presented. Major innovations are the use of high density microporous polyethylene for the restricted flow junction between the internal and external electrolyte and a polypropylene disposable pipette tip as the electrode body. Low electrolyte bleeding, reduced size, relatively low electrical resistance and simplified procedure of construction are some of the advantages of the presented design. These characteristics make this electrode particularly suitable for use with small-volume cells and flow cells, as well as applications where chloride contamination should be avoided. Other applications for the microporous membrane in electroanalysis are introduced.
Voltammetry Electrode

"Automatic Mercury Drop Electrode With Double Solenoid Activated Valve"
Electroanalysis 1992 Volume 4, Issue 6 Pages 635-642
Jairo Pedrotti, Lucio Angnes, Ivano G. R. Gutz*

Abstract: The construction and evaluation of a simple, low cost, and versatile automatic mercury electrode, working as dropping (DME), hanging (HMDE), or static drop electrode (SMDE), is described. Fast action of the needle valve is obtained with two solenoids, one for opening the valve and the other for closing it. The electrode can be controlled from a microcomputer or with a digital circuit. The performance of this electrode compares favorably with that of commercial ones in terms of area reproducibility (SD < 0.05%), response time of the valve, current profile during potentiostatic extrusion of the drop, and flexibility of use.

"Selective Determination Of Traces Of Copper By Adsorptive Accumulation Of Copper(I) Benzotriazolate, Transient Amalgamation And Anodic Stripping Voltammetry"
Electrochim. Acta 1998 Volume 43, Issue 23 Pages 3423-3429
Valberes B. Nascimentoa and Ivano G. R. Gutza,*

Abstract: Anodic stripping voltammetry with adsorptive accumulation of amalgam forming metals is proposed and demonstrated for the determination of traces of copper ions in, the presence of benzotriazole, HBTA (an excellent corrosion inhibitor for copper). The accumulation of the metal ions is accomplished, as customary, by adsorption on the mercury electrode of a coordination compound with a suitable ligand. Specifically, copper(II) is reduced to copper(I) and accumulated as the Cu(I)BTA complex on a hanging mercury drop electrode at 0.0 V vs SCE, under convection. Subsequently, copper(I) is reduced to the amalgam by applying a potential step to -0.4 V during 15 s or less. Finally, the potential is scanned in the positive direction and the differential pulse anodic peak of the re-oxidation of Cu(Hg) to Cu(I)BTA is recorded. A 2 min accumulation period provides a detection limit of 3 x 10^-9 M and an analytical curve linear up to 8 x 10^-7 M. Accumulation for 10 min (or more) lowers the detection limit to 8 x 10^-10 M (or lower). The new mode opens alternatives to improve the selectivity of cathodic stripping methods involving amalgam forming metals, and to reconsider ligands that give rise to unsatisfactory cathodic stripping peaks, such as HBTA.
Copper(II) Voltammetry Electrode Preconcentration

"Quick Production Of Gold Electrode Sets Or Arrays And Of Microfluidic Flow Cells Based On Heat Transfer Of Laser Printed Toner Masks Onto Compact Discs"
Electrochem. Commun. 2003 Volume 5, Issue 9 Pages 782-786
Daniela Daniel and Ivano Gebhardt Rolf Gutz

Abstract: A process is described to speedily produce in the laboratory, single or multiple coplanar gold electrodes of any shape and with sizes ranging from 100 µm to 10 cm, as well as to assemble microfluidic flow cells with them. The innovative combination of simple processes for ad hoc design and production uses readily available equipment and inexpensive materials, like recordable compact disks of the gold sputtered type. The following steps are involved: drawing of the electrode(s) on a microcomputer; laser printing of the design on wax paper; heat-transfer of the toner onto the gold surface of a peeled CD-R; etching of the gold layer from unprinted regions; removal of the toner with a solvent; activation; and use in conventional batch or flow cells. To obtain microfluidic flow cells with 7-12 µm interlayer gap, a gasket spacer of the desired shape is drawn and laser printed, the toner layer is heat transferred onto one CD piece with pre-etched electrodes and a second CD section is heat-sealed on top of it. The functionality of these electrodes as well as of the microfluidic flow cells is demonstrated by voltammetry and flow injection amperometric analysis.

"Adaptation Of Poly(tetrafluoroethylene) Tips To Mercury-drop Electrodes And Evaluation By Flow Injection Analysis"
Anal. Chem. 1993 Volume 65, Issue 4 Pages 500-503
Ivano G. R. Gutz, Lucio Angnes, and Jairo J. Pedrotti

Abstract: To overcome the effect of solution creeping between the Hg drop and the internal wall of the glass capillary in such electrodes, which can affect the area reproducibility of the drop as well as the drop time, a length (~3 cm) of PTFE tubing (0.051 mm i.d.; 0.35 mm o.d.) was heat-sealed at both ends and affixed by epoxy adhesive within a Tygon tube (1.6 mm o.d.). A 20-mm length of the combined tube was cut off and the orifice was conically widened to a depth of ~2 mm before gluing the tube within the drilled-out end (4-mm-deep cavity; 1.5 mm diameter) of a glass capillary tube; the lower end was then trimmed to a precise level. A dropping, hanging or static Hg electrode could easily be prepared from the tube assembly; a thick-walled PTFE tube could be used similarly and did not require enclosure within a Tygon reinforcing tube. A sessile static drop electrode prepared from thin-walled PTFE tubing was used as indicator, together with a Ag - AgCl electrode, in an amperometric flow cell in which a stainless steel needle acted as the cell outlet and the auxiliary electrode. This cell was applied in flow injection analysis for the determination of Cd in acidic medium and of As(III) in 0.1 M KOH medium. Repeated use of the same drop showed no degradation of response; for As, the linear dynamic range was 0.3 to 1500 ng.
Cadmium Electrode Teflon membrane Linear dynamic range

"Flow Injection Spectroelectroanalytical Method For The Determination Of Promethazine Hydrochloride In Pharmaceutical Preparations"
Anal. Chim. Acta 2003 Volume 494, Issue 1-2 Pages 215-224
Daniela Daniel and Ivano Gebhardt Rolf Gutz

Abstract: The first flow injection spectroelectroanalytical method for the determination of promethazine hydrochloride has been developed. It is based on the in situ detection of a colored cationic radical formed during electroxidation at a gold electrode in sulfuric acid medium (0.1 mol l-1) and it offers a number of advantages in terms of simplicity, rapidity, selectivity and sensitivity over many other approaches. The determination of promethazine hydrochloride in pure form or in pharmaceutical formulations was investigated, considering the amperometric and the absortiometric signal. Although the amperometric signal alone can be used for the determination of promethazine in simple formulations like Fenergan (Rhodia-Farma), the photometric signal might become decisive when other electroactive compounds, such as dipyrone, are present in the formulation, e.g. in Lisador (Farmasa).Promethazine was quantified in Fenergan and Lisador. The results obtained using either conventional calibration curves or standard additions, were equivalent to those obtained with the official method recommended in the British Pharmacopoeia (BP) and in agreement with the labeled composition, for Fenergan. For Lisador, the results for promethazine were within 2% of the nominal value informed by the producer and the official method could not be applied due to dipyrone interference.

"In-line TiO2-assisted Photodigestion Of Organic Matter In Aqueous Solution For Voltammetric Flow Analysis Of Heavy Metals In Water Samples"
Anal. Chim. Acta 2001 Volume 445, Issue 2 Pages 127-138
Andrea Cavicchioli and Ivano G. R. Gutz

Abstract: A novel enhanced photocatalytic digestion method for water samples, based on the addition, to the sample, of a suspension of TiO2 (anatase) and aiming at voltammetric heavy metal determination, is presented and evaluated. The quelate Cd(II)-EDTA acted as a model system in this investigation. The voltammetric wave of Cd(II) is effectively suppressed in the presence of EDTA in excess, but it experiences recovery as the coordinating capacity of the ligand is destroyed. It was observed that the presence of a TiO2 suspension 0.1% w/w neither affects the polarographic wave of the metal ion nor hinders its stripping voltammetry, although some catalyst adheres to the mercury drop. The retention of TiO2 on the electrode is further minimised by operating in the flow injection mode with renewable Hg drop electrodes. The voltammetry of samples of 1 mmol L-1 EDTA solutions, buffered with AcH/Ac- to pH 4 and containing 0.1 mmol L-1 Cd(II), collected during irradiation, revealed significant acceleration of the recovery of the Cd(II) signal in the presence of TiO2. It was demonstrated that the method is perfectly fit for flow analysis through a system that integrates the following stages: injection of sample, monosegmented with air bubbles; addition of TiO2 to the sample; in-line photodigestion; debubbling; degassing (dissolved O2 removal); accumulation of Cd(Hg) at the mercury electrode; and voltammetric stripping. Complete recovery of the 0.01 mmol L-1 Cd(II) signal was obtained for 150 µl sample plugs containing 0.1 mmol L-1 EDTA, after a transit time of 155 s in the irradiation chamber, at 30°C. Degradation of EDTA in real matrixes was also carried out.

"Overcoming Oxygen Quenching In Fluorescence Spectrometry With A Highly Efficient In-line Degassing Device Interfaced With A Flow Cell"
Anal. Chim. Acta 2000 Volume 422, Issue 2 Pages 131-137
Jairo J. Pedrotti, Solange Lima, Nina Coichev and Ivano G. R. Gutz

Abstract: To overcome the quenching effect of oxygen in fluorescence spectrometry, an in-line flow degassing device (FDD) was successfully applied to the removal of oxygen from sample solutions. The FDD consisted of a 3 m long coil of capillary silicone rubber tubing, installed in a glass flask maintained under reduced pressure of N-2 (2.400 Pa). To avoid recontamination of the emerging flow with O-2, the connection of the silicone tube with the fluorimetric cell is made with flexible silica capillary tube. Solutions can be injected with a syringe or feed with a pump. Aqueous solution of ruthenium(II) tris-bipyridil chloride, subject to quenching by oxygen, served as a luminescent probe. The performance was checked against independent amperometric measurements of O-2 with a Clark cell, that correlated well with the O-2 obtained from the fluorescence data using the Stern-Volmer relationship. At a flow rate of 1.0 mL min-1, the concentration of O-2 (measured amperometrically) dropped from 8.24 mg L-1 to 15 µg L-1 for a residence time of 34 s in the FDD, rendering the oxygen quenching effect on [Ru(bipy)(3)](2+) undetectable. The FDD compares favorably with direct inert gas purging of the solution in efficiency and speed. Moreover, it is compatible with flow injection analysis. A frequency of 35 determinations per hour was attained at 1 mL min-1, with good repeatability of the peaks (RSD = 0.8%, n = 25 injections of 200 µl of 1 x 10^-4 M [Ru(bipy)(3)](2+)).
Fluorescence Quenching Instrumentation

"A Fast, Highly Efficient, Continuous Degassing Device And Its Application To Oxygen Removal In Flow Injection Analysis With Amperometric Detection"
Anal. Chim. Acta 1994 Volume 298, Issue 3 Pages 393-399
Jairo J. Pedrotti, L&uacute;cio Angnes and Ivano G. R. Gutz

Abstract: A new continuous degassing device, based on the permeation of gases dissolved in a liquid through the walls of a narrow-bore polymeric tube, is described. The key innovation, responsible for the superior efficiency in relation to other designs, consists in maintaining a reduced pressure of an inert gas (N2, ~1600 Pascal) in the degassing chamber that contains the coiled polymeric tube wandered by the solution. When applied to the continuous removal of oxygen from an electrolyte in flow-injection analysis, FIA, with amperometric detection (flow of 1.0 ml/min, 34 s residence time), a decrease of at least 99.97% in the oxygen reduction current is experienced. Routine determination of 80 samples per hour of heavy metals like cadmium is afforded with a detection limit of about 10 ppb (1.8 x 10^-12 mol of Cd(II) for 20 µL injections), by using a sessile drop mercury electrode. FIA with pre-concentration followed by voltammetric stripping extends the detection limit to the sub-ppb level, as illustrated by monitoring lead and cadmium in samples of drinking water.
Amperometry Apparatus Gas diffusion Membrane