Interference-free determination of Ca in ultrapure water, concentrated acids and hydrogen peroxide using isotope dilution, ICP-MS and CH3F as a reaction gas

An analytical method was developed for Ca determination in ultrapure water, concentrated acids and hydrogen peroxide by ICP-MS, using CH3F as reaction gas in the dynamic reaction cell (DRC) and isotopic dilution (ID) as strategy of calibration for improve the accuracy and allow interference- free Ca determination

Isotope dilution analysis for particle mass determination using single-particle inductively coupled plasma time-of-flight mass spectrometry: application to size determination of silver nanoparticles

This paper describes methodology based on the application of isotope dilution (ID) in single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-ToFMS) mode for the mass determination (and sizing) of silver nanoparticles (AgNPs). For this purpose, and considering that the analytical signal in spICP-MS shows a transient nature, an isotope dilution equation used for online work was adapted and used for the mass determination of individual NPs. The method proposed measures NP isotope ratios in a particle-to-particle approach, which allows for the characterization of NP mass (and size) distributions and not only the mean size of the distribution. For the best results to be obtained, our method development (undertaken through the analysis of the reference material NIST RM 8017) included the optimization of the working conditions for the best precision and accuracy in isotope ratios of individual NPs, which had been only reported to date with multicollector instruments. It is shown that the precision of the measurement of these ratios is limited by the magnitude of the signals obtained for each NP in the mass analyzer (counting statistics). However, the uncertainty obtained for the sizing of NPs in this approach can be improved by careful method optimization, where the most important parameters are shown to be the selection of the spike isotopic composition and concentration. Although only AgNPs were targeted in this study, the method presented, with the corresponding adaptations, could be applied to NPs of any other composition that include an element with different naturally available isotopes

Detecting paraprotein interference on a direct bilirubin assay by reviewing the photometric reaction data

The direct bilirubin (D-Bil) assay on the AU Beckman Coulter instrumentation can be interfered by paraproteins, which may result in spurious D-Bil results. In a previous work, we took advantage of this fact to detect this interference, thus helping with the identification of patients with unsuspected monoclonal gammopathies. In this work, we investigate the possibility to detect interference based on the review of the photometric reactions, regardless of the D-Bil result. The D-Bil assay was carried out in a set of 2164 samples. It included a group of 164 samples with paraproteins (67 of which caused interference on the assay), as well as different groups of samples for which high absorbance background readings could also be expected (i.e. hemolyzed, lipemic, or icteric samples). Photometric reaction data were reviewed and receiver operating characteristics (ROC) curves were used to establish a cut-off for absorbance that best discriminates interference. The best cut-off was 0.0100 for the absorbance at the first photometric point of the complementary wavelength in the blank cuvette. Once the optimal cut-off for probable interference was selected, all samples analyzed in our laboratory that provided absorbance values above this cut-off were further investigated to try to discover paraproteins. During a period of 6 months, we detected 44 samples containing paraproteins, five of which belonged to patients with non-diagnosed monoclonal gammopathies. Review of the photometric reaction data permits the systematic detection of paraprotein interference on the D-Bil AU assay, even for samples for which reasonable results are obtained

High-resolution continuum source graphite furnace molecular absorption spectrometry for the monitoring of Sr isotopes via SrF formation: a case study

High-resolution continuum source graphite furnace molecular absorption spectrometry (HR CS GFMAS) can provide isotopic information under certain conditions, thus broadening its field of application. However, to date, only elements with two major stable isotopes have been monitored via this technique. In this work, the possibilities of HR CS GFMAS to determine isotope ratios of elements with more than two stable isotopes are evaluated for the first time. For this purpose, Sr was chosen as the analyte and SrF as the target species, so four different signals corresponding to four stable Sr isotopes (88Sr, 87Sr, 86Sr and 84Sr) should be distinguished. Nevertheless, due to the number of strontium isotopes, the shape of the peaks, and the resolution that the instrument exhibits in the spectral window, isotopic signals overlap, thus leading to potentially biased results. To circumvent this issue, a deconvolution protocol, consisting of measuring and correcting for the contribution of each isotope on the signals of the rest, was developed. These contributions were calculated as the signal ratio between the absorbance of the monoisotopic profile at the wavelengths where the maxima of other isotopes are expected and at its own maximum. Therefore, the interference can be simply subtracted from the net signal registered for the interfered isotope. The performance of this method was demonstrated for both naturally abundant and isotope-enriched Sr standards, paving the way for future applications in this field. Analysis of a real sample (tap water) spiked with a 84Sr solution is also demonstrated

Determinación directa de mercurio en sangre y orina por HR CS GFAAS con AuNPs como modificante químico

   Este trabajo usa la Espectrometría de Absorción Atómica con Horno de Grafito (HR CS GFAAS) para cuantificación de mercurio (Hg) en muestras certificadas (CRM) de orina y sangre, usando nanopartículas de oro (AuNPs) como modificante químico. Los porcentajes de recuperación obtenidos de muestras de CRM concuerdan con los valores de referencia (86 al 100%), presentando además valores de incertidumbre similares. &nbsp

Determination of chlorine via the CaCl molecule by high-resolution continuum source graphite furnace molecular absorption spectrometry and direct solid sample analysis

This work investigates the possibilities of high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of Cl in solid samples via the CaCl molecule and measurement of its molecular absorption. The method proposed is based on addition of 400 µg Ca as molecule-forming reagent and of 20 µg Pd as chemical modifier, which helps to stabilize the analyte and enhances sensitivity. The molecular spectrum for CaCl offers different lines with different limits of detection and linear ranges, which permitted to analyze solid samples with different Cl contents. The lowest limit of detection (0.75 ng Cl, corresponding to 0.75 µg g-1 for a typical sample mass of 1 mg) could be achieved by combination of three of the most sensitive lines in the vicinity of 620.862 nm, while the amplest linear range (up to 860 ng Cl) was achieved by selection of the less sensitive line at 377.501 nm. The method developed enabled the direct determination of Cl in solid samples using simple external calibration with aqueous standards. Good precision (5–9% RSD) and accuracy was attained in a series of certified samples of very different nature (i.e. coal, iron oxide, polyethylene, human hair, pine needles, rice flour and milk) and with very different Cl contents, ranging from about 50 µg g-1 to 1% (w/w) Cl. The method appears as particularly useful for Cl determination in samples with elevated Ca contents, for which biased results with other diatomic molecules, such as AlCl or SrCl, may be obtained

Estudio de las posibilidades de la absorción molecular de alta resolución empleando fuente continua en cámara de grafito para la medida de diferentes isótopos de Sr.

This work proposes the application of HR-CS-GF-MAS for the isotopic analysis of strontium as an approach to study the possibilities of the technique in the analysis of elements with multiple stable isotopes. For this purpose, the SrF molecule will be formed and corrections will be applied to obtain individual isotopic signals.Este trabajo plantea la aplicación de HR-CS-GF-MAS para el análisis isotópico de estroncio como una aproximación al estudio de las posibilidades de la técnica en el análisis de elementos con múltiples isótopos estables. Para ello, se formará la molécula de SrF y se aplicarán correcciones para obtener señales isotópicas individuales

Interference-free determination of Ca in ultrapure water, concentrated acids and hydrogen peroxide using isotope dilution, ICP-MS and CH3F as a reaction gas

An analytical method was developed for Ca determination in ultrapure water, concentrated acids and hydrogen peroxide by ICP-MS, using CH3F as reaction gas in the dynamic reaction cell (DRC) and isotopic dilution (ID) as strategy of calibration for improve the accuracy and allow interference- free Ca determination

Programa específico de preparación física para unidades Acorazadas/Mecanizadas

Este proyecto surge de la necesidad de dotar de un carácter específico a la formación física de las unidades Acorazadas/Mecanizadas, orientado a los requerimientos físicos propio de sus tareas y misiones en combate.Con este objetivo, se ha decidido crear un programa específico de preparación física para unidades Acorazadas/Mecanizadas, basado en el Modelo de Periodización Tradicional de Lev Matveev. Con el objetivo de evaluar las capacidades físicas trabajadas en el programa, se ha creado un nuevo test físico. Este test pretende complementar el Test General de la Condición Física, incluyendo un sistema de calificación propio para cada prueba basado en tres niveles: básico, intermedio y avanzado.Para determinar las capacidades físicas necesarias por las unidades Acorazadas/Mecanizadas, se ha realizado una encuesta a Cuadros de Mando del Regimiento Acorazado “Córdoba” nº 10 y del Regimiento de Infantería Mecanizada “La Reina” nº 2 y una entrevista con un Profesor de educación Física del Ejército de Tierra. Además, se ha evaluado la implicación de las capacidades físicas en diferentes tareas propias de este tipo de unidades. Para establecer qué marcas clasifican a un individuo según los niveles establecidos se ha realizado el nuevo test a un grupo de voluntarios del Regimiento Acorazado “Córdoba” nº 10. Mediante análisis estadístico de los resultados se ha creado una clasificación preliminar con rangos de clasificación para las diferentes pruebas.De esta forma, se concluye que añadir un carácter específico a la formación física mediante un programa de formación física exclusivo para unidades Acorazadas/Mecanizadas puede tener efectos positivos en la preparación física de dichas unidades. También se ha concluido que la Fuerza Muscular es la capacidad física más importante, seguida de la Resistencia Muscular, Flexibilidad y por último la Resistencia Cardiorrespiratoria.<br /

Cu fractionation, isotopic analysis, and data processing <i>via</i> machine learning: new approaches for the diagnosis and follow up of Wilson's disease <i>via</i> ICP-MS

Information about Cu fractionation and Cu isotopic composition can be paramount when investigating Wilson's disease (WD). This information can provide a better understanding of the metabolism of Cu. Most importantly, it may provide an easy way to diagnose and to follow the evolution of WD patients. For such purposes, protocols for Cu determination and Cu isotopic analysis via inductively coupled plasma mass spectrometry were investigated in this work, both in bulk serum and in the exchangeable copper (CuEXC) fractions. The CuEXC protocol provided satisfactory recovery values. Also, no significant mass fractionation during the whole analytical procedure (CuEXC production and/or Cu isolation) was detected. Analyses were carried out in controls (healthy persons), newborns, patients with hepatic disorders, and WD patients. While the results for Cu isotopic analysis are relevant (e.g., δ65Cu values were lower for both WD patients under chelating treatment and patients with hepatic problems in comparison with those values obtained for WD patients under Zn treatments, controls, and newborns) to comprehend Cu metabolism and to follow up the disease, the parameter that can help to better discern between WD patients and the rest of the patients tested (non-WD) was found to be the REC (relative exchangeable Cu). In this study, all the WD patients showed a REC higher than 17%, while the rest showed lower values. However, since establishing a universal threshold is complicated, machine learning was investigated to produce a model that can differentiate between WD and non-WD samples with excellent results (100% accuracy, albeit for a limited sample set). Most importantly, unlike other ML approaches, our model can also provide an uncertainty metric to indicate the reliability of the prediction, overall opening new ways to diagnose WD