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21. A time-based flow injection–cold vapor–atomic absorption spectrometry system with on-line microwave sample pre-treatment for the determination of inorganic and total mercury in urine1Presented at the Flow Analysis VII Conference held in Piracicaba, Brazil from 23–26 August 1997.1

Author

Gallignani, M, primary, Bahsas, H, additional, Brunetto, M.R, additional, Burguera, M, additional, Burguera, J.L, additional, and Petit de Peña, Y, additional

Published
1998
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39. On-line emulsification of lubricating oils in a flow-injection system for chromium determination by electrothermal atomic absorption spectrometry

Author

Burguera, José Luis, Salager, Raquel Anton de, Burguera, Marcela, Salager, Jean Louis, Róndon, Carlos, Carrero, Pablo, Gallignani, M., Brunetto, M. R., and Briceño, Marisol

Abstract

A simple and quick procedure has been developed for the on-line preparation of a one phase emulsion in a flow injection (FI) system for chromium determination by electrothermal atomic absorption spectrometry (ETAAS) with Zeeman-effect background correction. The entire FI system was controlled by a computer, independent of the spectrometer. A 1-ml plug of sample solution was injected into the carrier stream of hexane and was subsequently mixed with streams of 3.8% (m/v) sodium chloride, 5.0% (v/v) sodium dodecylsulfate (SDS) and 5.0% (v/v) of sec-butanol. The flow rates of the carrier, sodium chloride, SDS and sec-butanol streams were 1.0, 0.5, 0.5 and 0.2 ml min−1, respectively. The sonication of the flowing solutions improved the stability of the emulsion and provided quantitative recoveries. An emulsified sub-sample of 200-µl was collected in a capillary of a sampling arm assembly. Thereafter, 20 µl of this sample solution were introduced by means of positive displacement with air through a time-based solenoid injector (TBSI) in the graphite tube atomizer. The furnace program included two drying steps (at 110 and 130 °C) to minimize the sputtering of the sample in the atomizer. In all instances, the pyrolysis, atomization and cleaning temperatures of 1600, 2400 and 2500 °C were used to obtain good peak profiles with low background signals without the addition of any chemical modifier. The method provides a linear range for chromium from 7.0 to 50 µg l−1 and a limit of detection of 4.0 µg l−1, which corresponds to 6.0 ng g−1. The results were precise (0.6–0.8% RSD) and the recovery values found in the analysis of spiked samples ranged from 99.2 to 102.2%. The agreement between the observed and certified values obtained from two NIST Standard Certified Materials was good. The method described is satisfactory for determining chromium in new and used lubricating oil samples.

Published
2000

41. Determination of methylmercury and inorganic mercury in whole blood by headspace, cryofocusing gas chromatography and atomic absorption spectrometry

Author

R. Brunetto, M., R. Luna, J., Zambrano, A., Gallignani, M., Burguera, M., L. Burguera, J., and Petit de Peña, Y.

Abstract

A method for the determination of different mercury species in whole blood is described. Inorganic mercury (InHg) was determined in 2 ml of standard solutions or blood samples using head space (HS) injection coupled to atomic absorption spectrometry (AAS) after treatment with concentrated sulfuric and tin(II) chloride as a reductant agent in a closed HS vial. After stirring, the InHg was converted to elementary mercury and carried with a nitrogen flow through a quartz cell heated at 200 °C and the absorbance signal was evaluated by AAS. For the determination of methylmercury (MeHg), 2 ml of a standard solution or a blood sample were treated with 10 mg of iodoacetic acid and 0.4 ml of concentrated H2SO4. Then, the MeHg species were HS-injected into a gas chromatograph (GC), separated on a semicapillary column (AT-1000) with a flow of helium, then carried to the quartz cell heated at 1000 °C and detected by AAS. The high content of salts in blood samples, where sodium chloride is the major component (0.14 mol l–1), affected the gas–liquid distribution coefficient of both mercury species in the HS vial. A linear calibration graph was obtained in the ranges 1–20 and 1–125 µg Hg l–1 added as InHg and MeHg, respectively. The detection limits for InHg and MeHg were 0.6 and 0.2 µg Hg l–1, respectively. The relative standard deviations for eleven independent measurements were 5% for both mercury species. Recovery values ranging from 98 to 106% for InHg and from 95 to 105% for MeHg and from 93 to 95% for ethylmercury (EtHg) were obtained. The accuracy of the proposed method was also established by the analysis of certified whole blood samples for InHg and MeHg. No difference between the sum of these two species determined by our procedure and the recommended total mercury concentrations in the certified samples was observed. Results for the determination of MeHg and InHg in 30 controls and 30 dentists are presented to illustrate the practical utility of the proposed method.

Published
1999
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50. Development of a MSFIA sample treatment system as front end of GC-MS for atenolol and propranolol determination in human plasma.

Author

Brunetto Mdel R, Clavijo S, Delgado Y, Orozco W, Gallignani M, Ayala C, and Cerdà V

Subjects
Acetamides chemistry, Factor Analysis, Statistical, Flow Injection Analysis instrumentation, Fluoroacetates chemistry, Gas Chromatography-Mass Spectrometry methods, Humans, Microwaves, Sensitivity and Specificity, Trimethylsilyl Compounds chemistry, Atenolol blood, Flow Injection Analysis methods, Propranolol blood, Solid Phase Extraction methods
Abstract

An on-line solid-phase extraction (SPE) method coupled to gas chromatography-mass spectrometry (GC-MS) has been developed for the determination of atenolol (ATN) and propranolol (PRO) in human plasma. The hyphenation of SPE with multisyringe flow injection analysis (MSFIA) allows the simultaneous GC-MS determination of ATN and PRO with high selectivity and sensitivity. On-line preconcentration and derivatisation of the analytes were carried out by means of using restricted access materials (RAM) and microwave (MW) assisted derivatisation reactions with N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA)+1% trimethylchlorosilane (TMCS). Multivariate optimization was applied to optimize experimental conditions. The whole procedure comprising sample pretreatment and analyte determination took about 15 min. However, the overlap of the automatic sample treatment with the GC separation increased the frequency to 7 samples h(-1). The validated method was successfully applied to direct ATN and PRO determination in human plasma., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Published
2015
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