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Resano M.,University of Zaragoza | Aramendia M.,Centro Universitario Of La Defensa Academia General Militar Of Zaragoza | Belarra M.A.,University of Zaragoza
Journal of Analytical Atomic Spectrometry

The purpose of this review is to examine the literature devoted to direct sample analysis using high-resolution continuum source atomic absorption spectrometry in a tutorial way, in an attempt to provide guidelines on the most critical issues to consider when developing a new method. This review discusses in detail the advantages and limitations of this technique, highlighting its benefits in comparison with classic line source atomic absorption spectrometry instrumentation in the context of direct analysis of solid samples, slurries and complex liquid samples, trying to establish in which situations the use of this technique can be particularly beneficial. Some of the aspects that are addressed comprise: (i) the improved potential to detect and correct for spectral interferences; (ii) the different options to adjust the sensitivity to the analyte content; (iii) strategies to minimize matrix effects and calibrate with aqueous standard solutions; (iv) possibilities to carry out multi-element analysis. © 2014 The Royal Society of Chemistry. Source

Garcia-Gonzalez E.,Hospital Universitario Miguel Servet | Aramendia M.,Centro Universitario Of La Defensa Academia General Militar Of Zaragoza | Alvarez-Ballano D.,Hospital Universitario Miguel Servet | Trincado P.,Hospital Universitario Miguel Servet | Rello L.,Hospital Universitario Miguel Servet
Practical Laboratory Medicine

Objectives: Endogenous antibodies (EA) may interfere with immunoassays, causing erroneous results for hormone analyses. As (in most cases) this interference arises from the assay format and most immunoassays, even from different manufacturers, are constructed in a similar way, it is possible for a single type of EA to interfere with different immunoassays. Here we describe the case of a patient whose serum sample contains EA that interfere several hormones tests. We also discuss the strategies deployed to detect interference. Subjects and methods: Over a period of four years, a 30-year-old man was subjected to a plethora of laboratory and imaging diagnostic procedures as a consequence of elevated hormone results, mainly of pituitary origin, which did not correlate with the overall clinical picture. Results: Once analytical interference was suspected, the best laboratory approaches to investigate it were sample reanalysis on an alternative platform and sample incubation with antibody blocking tubes. Construction of an in-house 'nonsense' sandwich assay was also a valuable strategy to confirm interference. In contrast, serial sample dilutions were of no value in our case, while polyethylene glycol (PEG) precipitation gave inconclusive results, probably due to the use of inappropriate PEG concentrations for several of the tests assayed. Conclusions: Clinicians and laboratorians must be aware of the drawbacks of immunometric assays, and alert to the possibility of EA interference when results do not fit the clinical pattern. © 2015 The Authors. Source

Nakadi F.V.,Aragon Institute of Engineering Research | Nakadi F.V.,University of Sao Paulo | Da Veiga M.A.M.S.,Aragon Institute of Engineering Research | Da Veiga M.A.M.S.,University of Sao Paulo | And 4 more authors.
Journal of Analytical Atomic Spectrometry

This work investigates the possibility of obtaining Br isotopic information by generating a gaseous diatomic molecule in a graphite furnace and monitoring its absorption spectrum using a high-resolution continuum source device (HR CS GFMAS). Different metals (Al, Ba, and Ca) were investigated to produce this diatomic molecule and the most promising results, both in terms of isotopic shift and sensitivity, were obtained with Ca, thus leaving CaBr as the target species. The results demonstrate that, unlike what occurs when monitoring atomic spectra, which are characterized by very small isotopic shifts that can hardly be detected, using HR CS GFMAS it is feasible to observe several molecular transitions corresponding to Ca79Br and Ca81Br that are spectrally resolved (i.e. they act like two different molecules absorbing at different wavelengths), and can be simultaneously quantified. The method developed relies on the addition of both Pd and Ca (as a chemical modifier and molecule forming agent, respectively), the selection of peak height values and the use of IBC-m (iterative baseline correction for the monitoring of molecules) for setting the baseline. This method enables accurate Br isotopic analysis in 10 mg L-1 solutions with precision values around 2.5% RSD, without requiring any method for mass bias correction. Moreover, it is also demonstrated how the use of isotope dilution for calibration can help in circumventing severe chemical interferences (e.g., deriving from the presence of high amounts of Cl) when aiming at the direct determination of Br in solid samples by HR CS GFMAS. The accuracy of the method was evaluated via analysis of two different reference materials, poly(vinyl chloride) and tomato leaves. © The Royal Society of Chemistry 2016. Source

Aramendia M.,Centro Universitario Of La Defensa Academia General Militar Of Zaragoza | Florez M.R.,University of Zaragoza | Piette M.,Ghent University | Vanhaecke F.,Ghent University | Resano M.,University of Zaragoza
Journal of Analytical Atomic Spectrometry

In this work, a new methodology for direct determination of Al in whole blood samples by means of high-resolution continuum source graphite furnace molecular absorption spectrometry has been developed, based on the formation of the AlF diatomic molecule in the graphite furnace and the subsequent monitoring of its molecular absorption. The proposed methodology provides an alternative method to conventional atomic absorption, solving most of the problems related to the latter technique, particularly matrix effects, providing a straightforward alternative for blood analysis. The addition of NH 4F·HF, which is required for promotion of the AlF molecule, was found to improve sample matrix removal for whole blood samples, whether they contain EDTA or heparin as anticoagulant agents. Besides minimizing residues in the graphite platform, this circumstance enabled the use of aqueous standards to build a calibration curve, avoiding the need for the cumbersome method of standard additions, while not affecting significantly detection capabilities (1.8 μg L -1 LOD). The method developed was also used for exploring the possibilities of Al as a chemical marker assisting forensic diagnosis of death-by-drowning. For this purpose, a set of samples (water and blood) obtained from 8 drowning suspects and two controls were analysed for their Al levels. Although additional studies with a large number of samples would be needed in order to draw definitive conclusions from a forensic point of view, a positive correlation between Al concentration in the drowning water and Al concentration in the blood of drowning suspects was found, supporting the validity of Al as a marker for drowning diagnosis. © 2011 The Royal Society of Chemistry. Source

Aramendia M.,Centro Universitario Of La Defensa Academia General Militar Of Zaragoza | Aramendia M.,Aragon Institute of Engineering Research | Rello L.,Miguel Servet Universitary Hospital | Berail S.,University of Pau and Pays de lAdour | And 3 more authors.
Journal of Analytical Atomic Spectrometry

This work describes a novel procedure based on the use of a 1030 nm femtosecond (fs) laser ablation (LA) device operating at a high repetition rate (30000 Hz) coupled to a sector field-inductively coupled plasma-mass spectrometer (ICP-MS), enabling the complete ablation of dried blood spot (DBS) specimens in a reasonable time (200 s for samples of 5 μL). The integration of the complete signal obtained, in combination with the use of Pt as an internal standard (which can be added to the clinical filter paper prior to the blood deposition, ensuring compatibility with unsupervised sample collection schemes), permits obtaining an analytical response that is independent of the particular characteristics of every sample. On the basis of this methodology, an analytical method was developed for the direct determination of several elements (Cd, Co, Cu and Pb) in four blood reference materials as well as in three real samples, providing accurate results in all cases evaluated, at concentration levels ranging from 0.1 to hundreds of μg L-1. Detection limits of 0.043 (Cd), 0.42 (Co), 0.54 (Cu), and 0.040 (Pb) μg L-1 are achieved, and precision values most often range between 3 and 9% RSD. Finally, the potential to couple the LA device simultaneously to a multicollector-ICP-MS and a sector field-ICP-MS unit by split-flow is also demonstrated, thus allowing us to obtain both elemental (Co, Cu, Cd and Pb) and isotopic (Cu isotopic composition) information from every particular DBS, and therefore maximizing the amount of information that can be drawn from a single DBS specimen. Still, the precision of the approach is limited at this point, as RSD values of approx. 1500 ppm and delta variations of almost 4‰ were observed for five DBS specimens created from the same blood sample. This journal is © The Royal Society of Chemistry. Source

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