Slurry sampling in serum blood for mercury determination by CV-AFS

The heavy metal mercury (Hg) is a neurotoxin known to have a serious health impact even at relatively low concentrations. A slurry method was developed for the sensitive and precise determination of mercury in human serum blood samples by cold vapor generation coupled to atomic fluorescence spectrometry (CV-AFS). All variables related to the slurry formation were studied. The optimal hydrochloric concentration and tin(II) chloride concentration for CV generation were evaluated. Calibration within the range 0.1-10 μg L-1 Hg was performed with the standard addition method, and compared with an external calibration. Additionally, the reliability of the results obtained was evaluated by analyzing mercury in the same samples, but submitted to microwave-assisted digestion method. The limit of detection was calculated as 25 ng L-1 and the relative standard deviation was 3.9% at levels around of 0.4 μg L-1 Hg.Fil: Aranda, Pedro Rodolfo. Universidad Nacional de San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gil, Raul Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Moyano, Susana. Universidad Nacional de San Luis; ArgentinaFil: de Vito, Irma Esther. Universidad Nacional de San Luis; ArgentinaFil: Martinez, Luis Dante. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis; Argentin

Laser-induced fluorescence integrated in a microfluidic immunosensor for quantification of human serum IgG antibodies to Helicobacter pylori

A portable immunosensor coupled to laser-induced fluorescence (LIF) detection system has been successfully developed. It was applied to the quantitative determination of specific IgG antibodies against Helicobacter pylori present in human serum samples. This system is a relevant alternative tool for the diagnostic of peptic ulcer and gastritis diseases produced by H. pylori, which are recognized risk factors for the development of gastric mucosa associated lymphoid tissue lymphoma and gastric adenocarcinoma. More than 50% of the population has been affected by H. pylori, one of the most widespread infections around the world. Our proposed system combines the LIF detection, which offers great sensibility with the specificity of the immunological reactions and the microfluidic technology. The device has a central channel (CC) with packed H. pylori antigen immobilized on 3-aminopropyl-modified controlled pore glass (AP-CPG). Antibodies in serum samples reacted immunologically with the immobilized antigen and then, they were determined using alkaline phosphatase (AP) enzyme-labeled second antibodies specific to human IgG. The 4-methylumbelliferyl phosphate (4-MUP), employed as enzymatic substrate, was converted to soluble fluorescent methylumbelliferone by AP, and this fluorescent product was finally quantified by LIF detection system. The calculated detection limits for LIF detection and the ELISA procedure were 0.17 and 2.1 U mL -1, respectively, and the within- and between-assay coefficients of variation were below 5.1%.Fil: Seia, Marco Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Pereira, Sirley Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Carlos A. Fontán. Universidad Nacional de San Luis; ArgentinaFil: de Vito, Irma Esther. Universidad Nacional de San Luis; ArgentinaFil: Messina, Germán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Zinc oxide nanoparticles based microfluidic immunosensor applied in congenital hypothyroidism screening

In this article, we present an innovative approach for congenital hypothyroidism (CHT) screening. This pathology is the most common preventable cause of mental retardation, affecting newborns around the world. Its consequences could be avoided with an early diagnosis through the thyrotropin (TSH) level measurement. To accomplish the determination of TSH, synthesized zinc oxide (ZnO) nanobeads (NBs) covered by chitosan (CH), ZnO-CH NBs, were covalently attached to the central channel of the designed microfluidic device. These beads were employed as platform for anti-TSH monoclonal antibody immobilization to specifically recognize and capture TSH in neonatal samples without any special pretreatment. Afterwards, the amount of this trapped hormone was quantified by horseradish peroxidase (HRP)-conjugated anti-TSH antibody. HRP reacted with its enzymatic substrate in a redox process, which resulted in the appearance of a current whose magnitude was directly proportional to the level of TSH in the neonatal sample. The structure and morphology of synthesized ZnO-CH NBs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The calculated detection limits for electrochemical detection and the enzyme-linked immunosorbent assay procedure were 0.00087 μUI mL-1 and 0.015 μUI mL-1, respectively, and the within- and between-assay coefficients of variation were below 6.31 % for the proposed method. According to the cut-off value for TSH neonatal screening, a reasonably good limit of detection was achieved. These above-mentioned features make the system advantageous for routine clinical analysis adaptation.Fil: Seia, Marco Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Pereira, Sirley Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Fernández Baldo, Martín Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: de Vito, Irma Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Messina, Germán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; Argentin

Screen-printed immunosensor for quantification of human serum IgG antibodies to Helicobacter pylori

This paper describes the development of a screen-printed immunosensor for the rapid and sensitive quantification of human serum immunoglobulin G (IgG) antibodies to Helicobacter pylori. This microorganism cause peptic ulcers and chronic gastritis, affecting around the 10% of the world population. Antibodies in the serum sample are allowed to react immunologically with the purified H. pylori antigens that are immobilized on graphite screen-printed electrodes (GSPE). The bound antibodies are quantified by alkaline phosphatase (AP) enzyme-labeled second antibodies specific to human IgG. p-Aminophenyl phosphate (p-APP) was converted to p-aminophenol (p-AP) by AP, and an electroactive product was quantified using Osteryoung square wave voltammetry (OSWV). The electrochemical detection can be done within 1 min and total assay time was 25 min. The calculated detection limits for electrochemical detection and the ELISA procedure are 0.5 and 1.8 U ml-1, respectively. Reproducibility assays were made using repetitive standards of H. pylori specific antibody (measured as the activity of the correspondent anti-serum's enzyme conjugated) and the intra- and inter-assay coefficients of variation were below 5%. The electrochemical immunosensor showed higher sensitivity and lower time consumed than the standard spectrophotometric detection ELISA method, demonstrate its potential usefulness for early assessment of human serum immunoglobulin G (IgG) antibodies to H. pylori. © 2007 Elsevier B.V. All rights reserved.Fil: Messina, Germán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: de Vito, Irma Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

On-line microfluidic sensor integrated with an enzyme-modified pre-cell for the monitoring of paracetamol in pharmaceutical samples

An on-line microfluidic sensing device with an enzyme-modified pre-cell coupled to an amperometric detector for the monitoring of paracetamol in pharmaceutical formulations is described. Horseradish peroxidase (HRP) [EC 1.11.1.7], immobilized on a 3 μl pre-cell, in presence of hydrogen peroxide catalyses the oxidation of paracetamol to N-acetyl-p-benzoquinoneimine. The electrochemical reduction back to hydroquinone is detected on glassy carbon electrode surface at -0.10 V. The recovery of paracetamol from 10 samples ranged from 99.00 to 101.10%. This method could be used to determine paracetamol concentration in the range 0.35-100 μM (r = 0.997) with a limit of detection of 3.0 × 10-7 M and a relative standard deviation was less than 4.1% (n = 8). The method was successfully applied for the processing of as many as 20 samples per hour of paracetamol in pharmaceutical formulations.Fil: Messina, Germán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: de Vito, Irma Esther. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Enrichment method for trace amounts of rare earth elements using chemofiltration and XRF determination

A preconcentration method for subsequent determination of rare earth elements (REE) by X-ray fluorescence (XRF) spectrometry was developed. The method is based on using (o-[3,6-disulfo-2-hydroxy-l-naphthylazo]-benzenearsonic acid) (Thorin) as acomplexing agent which is retained on a polyamide membrane by a chemofiltration process. The pH dependence of the chemofiltration of these metal ions on the membrane and other variables, such as flow-rate, contact time, kinetic of complex formation, etc. were determined. The membrane containing the chemofiltrate formed a thin film, which eliminated the interelemental effects when measured by XRF. The detection limits were 23, 23 and 49 ng/mL for Sm(III), Eu(III) and Gd(III), respectively. High enrichment factors were obtained. The method was successfully applied to the preconcentration of Sm(III), Eu(III) and Gd(III) from different samples.Fil: de Vito, Irma Esther. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Analítica; ArgentinaFil: Olsina, Roberto Antonio. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Analítica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Masi, Adriana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química. Área de Química Analítica; Argentin

Preconcentration and elimination of matrix effects in XRF determinations of rare earth elements by preparing a thin film through chemofiltration

Trace rare earth elements (REE) can be enriched by collecting them on a filter after they have formed their complexes with 2,2′-(1,8-dihydroxy-3,6-disulfonaphthylene-2,7-bisazo) bisbenzenearsonic acid (Arsenazo III) through a process called chemofiltration. The filter, which constitutes a thin film, is passed directly to the X-ray fluorescence (XRF) spectrometer, eliminating, in this manner, the interelemental effects produced in XRF determinations. High preconcentration factors and low detection limits are obtained: 18.3 ng mL-1 for Sm, 17.5 ng mL-1 for Eu and 34 ng mL-1 for Gd. The method was applied to the determination of these elements in NIST standard reference glasses with very good precision.Fil: de Vito, Irma Esther. Universidad Nacional de San Luis; ArgentinaFil: Olsina, Roberto Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Masi, Adriana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Removal of arsenic(V) ions from aqueous media by adsorption on multiwall carbon nanotubes thin film using XRF technique

A solid phase extraction using multiwalled carbon nanotubes, modified with a tertiary amine, ALIQUAT 336, has been developed as a preconcentration technique for the determination of trace amounts of As(V) in water samples. After "batch-based mode" As(V) adsorption on ALIQUAT 336-Multiwalled carbon nanotubes, determinations were made directly on the solid by X-Ray Fluorescence spectrometry, which reduces the number of reagents used and minimizes the sample handling. The method herein described combines the advantages of solid phase extraction with the benefits of any X-Ray Fluorescence method associated to the large areas held by the carbon nanotubes, which make them a promising solid sorbent for preconcentration procedures. The enrichment factor was calculated considering that the thin film obtained from the 100 mL solution of 1000 μg L-1 As had a final thickness of 0.04 mm and a final diameter of 16.7 mm, the volume deposited on the pellet was 0.0088 cm3. Thus the preconcentration factor obtained was 104 fold, which represented a highly satisfactory value for trace analysis by X-Ray Fluorescence. Satisfactory results were obtained for the determination of arsenic in samples of the standard reference material "NIST 1643e - Trace Elements in Water and drinking water".Fil: Aranda, Pedro Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Llorens, Ivan. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química Analítica; ArgentinaFil: Perino, Ernesto. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química Analítica; ArgentinaFil: de Vito, Irma Esther. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química Analítica; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Solid-phase preconcentration and determination of mercury(II) using activated carbon in drinking water by X-ray fluorescence spectrometry

A novel and simple method was developed for the preconcentration and determination of mercury(II) from hydrochloric acid solutions through their adsorption on Aliquat 336 (tri-octylmethylammonium chloride)-activated carbon. The determinations were made directly on the solid by X-ray fluorescence spectrometry, which had the advantage of eliminating the step of elution of the mercury retained. This preconcentration system enabled the determination of Hg(II) in drinking water samples at µg l−1 levels. A 1700-fold enrichment factor was obtained. The described methodology showed excellent reproducibility, accuracy, and detection limits improvement by eliminating the step of elution of the analyte, replacing those methods based on cold vapor generation, reducing reagent consumption, and handling of samples.Fil: Aranda, Pedro Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Colombo, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Perino, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: de Vito, Irma Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; Argentin

Solid phase extraction of chromium(VI) using Aliquat336 immobilized on a thin film of multiwall carbon nanotubes

We report on a novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples. Cr(VI) is adsorbed - in a "batch mode" - on multiwalled carbon nanotubes covered with Aliquat 336 and then determined directly, i. e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling. The method combines the advantages of solid-phase extraction with the benefits of the XRF method in that the large areas required by the carbon nanotubes make them a promising solid sorbent for preconcentration. The enrichment factor was calculated after considering that the thin film obtained from the 10 mL solution of 1 mg L -1 of Cr(VI) has a real thickness of 0. 04 mm and a final diameter of 16. 7 mm, so that the volume deposited on the pellet is 0. 0088 cm 3 and the preconcentration factor is 1000.Fil: Aranda, Pedro Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina; ArgentinaFil: Perino, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina; ArgentinaFil: Bertolino, Franco Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina; ArgentinaFil: Raba, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina; ArgentinaFil: de Vito, Irma Esther. Química Analitica; Facultad de Quimica Bioquimica y Farmacia; Universidad Nacional de San Luis; Argentin