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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Aurora G. Coedo

Abbrev:
Coedo, A.G.
Other Names:
Address:
CISC, Centro Nacional de Investigaciones Metalúrgicas, Avda Gregorio Amo 8, E-28040 Madrid, Spain
Phone:
+34-91-5538900
Fax:
+34-91-5347425

Citations 9

"Evaluation Of Different Sample Introduction Approaches For The Determination Of Boron In Unalloyed Steels By Inductively Coupled Plasma Mass Spectrometry"
Spectrochim. Acta B 2005 Volume 60, Issue 1 Pages 73-79
A.G. CoedoCorresponding Author Contact Information, E-mail The Corresponding Author, M.T. Dorado and I. Padilla

Abstract: An extended study of different sampling introduction approaches using inductively coupled plasma mass spectrometry (ICP-MS) is presented for the determination of boron in steel samples. The following systems for sample introduction were applied: direct sample solution nebulization by continuous nebulization (CN) using a cross-flow nebulizer and with flow injection (FI), applied to 0.1% (m/v) and 0.5% (m/v) sample solutions, respectively; FI after iron matrix extraction, using acetylacetone-chloroform, and isotopic dilution (ID) analysis as the calibration method; FI with on-line electrolytic matrix separation; and spark ablation (SA) and laser ablation (LA) as solid sampling techniques. External calibration with matrix-matching samples was used with CN, SA, and LA, and only acid solutions (without matrix matching) with FI methods. When FI was directly applied to a sample solution, the detection limit was of 0.15 ?g g-1, improving by a factor of 4 that was obtained from the CN measurements. Isotopic dilution analysis, after matrix removal by solvent extraction, made it possible to analyze boron with a detection limit of 0.02 ?g g-1 and, with the on-line electrolytic process, the detection limit was of 0.05 ?g g-1. The precision for concentrations above 10 times the detection limit was better than 2% for CN, as well as for FI methods. Spark and laser ablation sampling systems, avoiding digestion and sample preparation procedures, provided detection limits at the ?g g -1 levels, with RSD values better than 6% in both cases. Certified Reference Materials with B contents in the range 0.5-118 ?g g-1 were used for validation, finding a good agreement between certified and calculated values. © 2004 Elsevier B.V. All rights reserved.

"Evaluation Of Flow Injection Sample To Standard Addition Method For The Inductively Coupled Plasma Mass Spectrometric Determination Of Aluminum In Biological Tissues"
J. Mass Spectrom. 1996 Volume 31, Issue 4 Pages 427-432
A. G. Coedo*, M. T. Dorado, J. Ruiz, M. Escudero, J. C. Rubio

Abstract: Tissues were minced, dried and powdered. Portions (0.5 g) were oxidized with 4 mL HNO3 in a microwave apparatus, with a 7-step heating programme. The solution was evaporated almost to dryness, mixed with a solution containing 1 µg Sc(III) (internal standard to compensate for plasma and ion signal instability) and diluted to 25 mL with 0.1% HNO3. Portions (0.5 ml) of this solution were injected into the carrier (2.8 ml/min) containing an Al(III) standard of 20 ng/ml and 40 ng/nl of Sc(III) in 0.1% HNO3 and this was followed by the injection of 0.5 mL of a digestion blank. The injection valve was located a few cm away from the cross-flow nebulizer and the ions 27Al and 45Sc were measured. The sample concentration then corresponded to the difference between the signals for the sample (maximum) and the blank (minimum). The method has the advantages of requiring less sample, being quicker and minimizing salt deposition on the sample and skimmer cones. Results for reference materials were similar to those obtained by conventional standard additions. Recovery of 0.5-10 ppm Al(III) was close to 100%. The detection limit was 10 ppb.
Aluminum(III) Biological tissue Mass spectrometry Sample preparation Calibration Reference material Standard additions calibration

"On-line Ion-exchange Matrix Separation And Inductively Coupled Plasma Mass Spectrometric Determination Of Trace Impurities In High-purity Aluminum"
J. Anal. At. Spectrom. 2002 Volume 17, Issue 5 Pages 502-506
A.-G. Coedo, M. T. Dorado and I. Padilla

Abstract: The feasibility of using an anion-exchange resin for on-line separation of trace amounts of Fe, Cu, Mn, Mg, Cr, Ni, Zn, Co, Pb, and Cd from pure aluminum was investigated. A test portion of 50 mg of aluminum drillings was dissolved with 6 mL of a buffer solution, 2.64% (m/v) NaOH-0.91% (m/v) KCl (pH = 13.4±0.1). An aliquot of 500 µL of the solution obtained was passed through a micro-column, included in a flow injection (FI) manifold, packed with a 2 + 1 mixture of Metalfix Chelamine and Hyphan Cellulose (the micro-column volume was about 150 µL). The retained trace elements were eluted in the back-direction with 200 µL of a 3 + 1 mixture of 1 mol L-1 HCl-1 mol L-1 HNO3 and then determined using flow injection inductively coupled plasma mass spectrometry. The operating parameters and operational scheme of the manifold of the FI on-line ion-exchange assembly are given. The accuracy of the proposed method was tested by analyzing a pure aluminum standard sample (Aluminum Pechiney, CODE 566). Recoveries from 50 mg test portions of a high-purity aluminum (99.999%) spiked with 2.5 and 25 ng each of the studied analytes were close to 100%, and the relative standard deviations ranged from 1 to 3%. Determination limits (10s) were in the ng g-1 range.
Preconcentration

"Use Of Boric Acid To Improve The Microwave-assisted Dissolution Process To Determine Fluoride Forming Elements In Steels By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 10 Pages 1193-1197
Aurora G. Coedo, M. Teresa Dorado, Isabel Padilla and Francisco J. Alguacil

Abstract: The applicability of FI-ICP-MS combined with microwave sample digestion for the simultaneous determination of trace amounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in iron and steel samples was studied. The use of hydrofluoric acid in the sample dissolution process produced nearly invisible insoluble particles with the REEs, leading to erroneous quantification of these elements. The addition of boric acid, complexing HF, solved this problem. By monitoring the transient signals produced by the FI microsampling system, it was possible to evaluate the effectiveness of the sample dissolution procedure. Severe depressive matrix effects caused by the sample matrix were encountered when the signals were compared with those from HNO3 solutions; in contrast, no effects were observed with the addition of boric acid. A highly alloyed steel, stainless steel certified reference material JK 37 (Sandvik Steel), was used to evaluate the effectiveness of the dissolution procedure and to develop the method. The limits of quantification (LOQ) calculated from 10.sqroot.s ranged between 0.008 µg g-1 for Lu and 0.040 µg g-1 for Nd. The relative standard deviation for all the analytes was better than 3% (n=4) for concentrations >10 times the LOQ.
Lanthanum Cerium Praseodymium Neodymium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Metals, lanthanides Alloy Mass spectrometry Sample preparation Reference material Interferences

"Study Of The Application Of Air-water Flow Injection Inductively Coupled Plasma Mass Spectrometry For The Determination Of Calcium In Steels"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 11 Pages 1037-1041
A. G. Coedo, M. T. Dorado, I. Padilla and F. J. Alguacil

Abstract: Steel shavings (0.25 g) and 100 ng Sc (internal standard) were transferred to a PTFE microwave digestion vessel, together with 5 mL HCl, 2 mL HNO3 and 0.1 mL HF, the vessel was sealed and subjected to 360 W of microwave power for 30 min. The solution was transferred to a PTFE beaker, mixed with 1 mL HF and 0.75 mL H2SO4 and evaporated to white fumes. This step eliminates isobaric interference from 12C16O2 and 28Si16O. The liquid was diluted to 50 mL. The Fe(III) matrix was removed from 20 mL by electrolysis at a Hg cathode. Portions (0.2 ml) were injected into the air segment (1.8 ml/min) of an air-0.5% HNO3 carrier by valve programming and the carrier was transported directly into the ICP mass spectrometer for measurement of the 44Ca peak (to avoid Ar interference with the 40Ca peak). Sensitivity was increased by a factor of three compared with injection into a continuous-flow of aqueous carrier. Calibration graphs were linear for 20-200 ng/l of Ca(II) solutions in 1.5% H2SO4 and containing 2 ng/l of Sc. The detection limit was 3 ng/ml, corresponding to 0.6 ppm Ca in the sample. At the detection li the RSD (n = 5) was 15%, decreasing to 1% above 30 ng/ml. The method was applied to the analysis of four reference steels (12-28 ppm Ca).
Calcium-44 Alloy Sample preparation Mass spectrometry Reference material Interferences

"Determination Of Trace Elements In Unalloyed Steels By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 6 Pages 449-453
Aurora G. Coedo and Teresa Dorado

Abstract: Steel (250 mg) was treated with 7 mL 65% HNO3, 200 µL 40% HF and 3 mL water and the mixture was digested in a microwave oven (program details given). The oven was cooled, the contents were transferred to a calibrated flask and 2.5 µg each of Be, Tl and Rh (internal standards) were added. The solution was diluted to 50 mL with 1% HNO3 and a 250 µL portion of the solution was pumped into the nebulizer (2.8 ml/min), mixed with the nebulizer gas (1.1 ml/min) and analyzed by ICP-MS (operating conditions given). The RSD was 3% for all analytes at concentrations 1 µg/g. The method was applied to the analysis of two pure Fe reference materials (BCR CRM 097 and NIST SRM 365). Results agreed well with certified values.
Trace elements Alloy BCR 97 NIST 365 Mass spectrometry Sample preparation Internal standard Reference material

"Isotope Dilution Analysis For Flow Injection ICP-MS Determination Of Microgram Per Gram Levels Of Boron In Iron And Steel After Matrix Removal"
Anal. Chem. 1996 Volume 68, Issue 6 Pages 991-996
Aurora G. Coedo, Teresa Dorado, Bernardo J. Fernandez, and Francisco J. Alguacil

Abstract: Steel or Fe (0.25 g) was mixed with HCl, HNO3, H2SO4 and water in a high-pressure digestion vessel and dissolved using a microwave oven. A 10B spike solution was added (250 ng B) and the solution was evaporated to form solid salts, which were redissolved in water. The solution was extracted with acetylacetone/CHCl3 (1:1) at pH 1.4, the organic phase was discarded, and the extraction procedure was repeated on the aqueous phase. The aqueous layer was mixed with 1 mL HNO3, the solution was evaporated to 2 mL and diluted to 5 mL with water. The resulting test solution corresponded to 50 mg/ml sample, with the total B and Fe contents 1 µg/ml. Flow injection sampling minimized problems arising from the total salt concentration. The ICP-MS detection limit was 0.02 µg/g and the RSD values for concentrations 10 times this limit were 1% (n = 4). Good accuracy was obtained for eight Fe reference materials with B contents 10 µg/g.
Boron Metal Alloy NIST 361 NIST 363 NIST 951 NIST 365 BAM 285-1 BAS ECRM-097-1c BAS ECRM-281-1 ISIJ JSS-002-2 Mass spectrometry Sample preparation Reference material Interferences Matrix removal

"A Micro-scale Mercury Cathode Electrolysis Procedure For Online Flow Injection Inductively Coupled Plasma Mass Spectrometry Trace Elements Analysis In Steel Samples"
Anal. Chim. Acta 1999 Volume 389, Issue 1-3 Pages 247-255
Aurora G. Coedo, Isabel Padilla, Teresa Dorado and Francisco J. Alguacil

Abstract: An online matrix-analyte separation technique was developed for flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS) trace analysis. A µelectrolytic cell was designed to be inserted in the FI manifold. The technique was used to separate Zr, Hf, Y, rare earth elements (REEs), Th and U from a steel-matrix (Fe, Cr, Ni, Co, Mn and Mo). A microwave-assisted HNO3-HCl-HF-H2SO4 digestion procedure, with temperature/pressure regulation, was used for sample dissolution. Obtained solutions were evaporated to SO3 fumes, and 2 mi of this diluted sulfuric solution were introduced in the electrolytic cell through the manifold circuit. After matrix removal, the electrolyte was conducted to load a 300 µl sample loop to be injected into the plasma torch. Direct multielement standard solutions in diluted sulfuric acid (without matrix matching and sample pretreatment) were applied for external calibration. The determination limits, with reference to the solid, were improved by a factor of about 10 compared with that obtained from direct measurements of 0.1% (m/v) sample solutions. The relative standard deviations for all the analytes were better than 3.5% for concentrations above 10 times the limit of quantification. The developed method was applied in the determination of certified elements in Steel Reference Materials: NIST 363 and NIST 364. Recoveries from 0.200 g test portions of high-purity iron spiked at two different concentration levels were found better than 97%.
Zirconium Yttrium Hafnium Metals, rare earth Thorium-232 Uranium Lanthanum Lutetium Cerium Praseodymium Neodymium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Ytterbium Thallium NIST 363 NIST 364 Mass spectrometry Matrix removal Extraction

"Online Ion-exchange Separation And Determination Of Niobium, Tantalum, Tungsten, Zirconium, And Hafnium In High-purity Iron By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
Anal. Chim. Acta 1995 Volume 315, Issue 3 Pages 331-338
Aurora G. Coedo*, Teresa D. López and F. Alguacil

Abstract: A study was made to investigate the feasibility of using an anion-exchange resin for on-line separation of trace amounts of niobium, tantalum, tungsten, zirconium and hafnium from iron matrix samples. The incorporation of a micro-column packed with Dowex 1X8-100 ion-exchange resin into a flow injection system is presented. The detection was done with inductively coupled plasma mass spectrometry (ICP-MS). The sample treatment, optimization of analytical variables and measurable concentration levels are discussed. Recoveries from standard additions to a high-purity iron were for all the analytes close to 100%, with relative standard deviations ranging from 0.7 to 3.0%. The limits of quantification (10 sn-1) calculated from a 5% (m/v) iron sample solution were 8, 5, 14, 12 and 10 ng g-1 for Nb, Ta, W, Zr and Hf, respectively. The accuracy of the proposed method was tested by determining these elements in Euronorm-CRM 098-1 reference material. Recoveries from 0.250 g test portions of the above reference material spiked with 2.5 and with 12.5 ng each of the five analytes are reported.
Niobium Tantalum Tungsten Zirconium Hafnium High purity Ion exchange Mass spectrometry