http://hdl.handle.net/10045/2352 2013-05-18T12:12:10Z http://hdl.handle.net/10045/3267 Título: Use of ICP-AES as a HPLC detector for the determination of carbohydrates, carboxylic acids and metals in wines and several native varieties of tomato Autor/es: Paredes Paredes, Eduardo; Prats Moya, Soledad; Maestre Pérez, Salvador; Todolí Torró, José Luis Descripción: Comunicación presentada en la VI Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines, Vigo, 8-10 noviembre 2006 2007-11-26T14:40:54Z http://hdl.handle.net/10045/2752 Título: Sample introduction systems for the analysis of liquid microsamples by ICP-AES and ICP-MS Autor/es: Todolí Torró, José Luis; Mermet, Jean Michel Resumen: There are many fields in which the available sample volume is the limiting factor for an elemental analysis. Over the last ten years, sample introduction systems used in plasma spectrometry (i.e., Inductively Coupled Plasma Atomic Emission Spectrometry, ICP-AES, and Mass Spectrometry, ICP-MS) have evolved in order to expand the field of applicability of these techniques to the analysis of micro- and nanosamples. A full understanding of the basic processes occurring throughout the sample introduction system is absolutely necessary to improve analytical performance. The first part of the present review deals with fundamental studies concerning the different phenomena taking place from aerosol production to analyte excitation/ionization when the liquid consumption rate does not exceed 100μl/min. Existing sample introduction systems are currently far from the ideal and a significant effort has been made to develop new and efficient devices. Different approaches for continuously introducing small sample volumes (i.e., microsamples) have been reviewed and compared in the present work. Finally, applications as well as basic guidelines to select the best sample introduction system according to the sample particularities are given at the end of this review. 2006-03-01T00:00:00Z http://hdl.handle.net/10045/2751 Título: Compensation for matrix effects in ICP-AES by using air segmented liquid microsample introduction. The role of the spray chamber Autor/es: Todolí Torró, José Luis; Maestre Pérez, Salvador; Mermet, Jean Michel Resumen: The combination of sample injection into an air carrier stream (i.e., air segmentation) with a low sample consumption system has been evaluated for the analysis of microsamples through ICP-AES. A PFA micronebulizer has been coupled to: (i), a double pass spray chamber; (ii), a Cinnabar cyclonic spray chamber; and (iii), a torch integrated sample introduction system, TISIS. Three matrices have been studied: in addition to water two concentrated acid solutions (2 mol l–1 nitric acid and 1.7 mol l–1 acetic acid) and Na 5,000 µg ml–1. A simulation of the evolution of the drop size distributions of the aerosols with time was carried out in order to evaluate the extent of solvent evaporation inside the chamber. The total mass of solvent evaporated inside the chamber was estimated and it was concluded that, at 25 °C, about 4–6 s residence time were required to promote the maximum evaporation of the solvent. In order to ensure this, discrete sample introduction into an air carrier stream (i.e., air segmentation) was used. Narrow peaks (i.e., with a full width at half maximum, FWHM, as short as 10 s) were obtained for a 10 µl injected sample. The peaks found for the Cinnabar and TISIS were narrower than those for the double pass spray chamber. More importantly, the interferences caused by inorganic as well as organic matrices were less severe in discrete than in continuous mode. The theoretical simulations allowed explanation of these results in terms of the enhancement of the solvent evaporation both for water and matrices in this operating mode. The enhanced solvent evaporation with respect to the situation in continuous mode minimized differences in analyte transport towards the plasma induced by these compounds. Despite this, in discrete mode a residual matrix effect was found that was attributed to the aerosol transport process. Internal standardization (IS) was applied to transient signals and the interferences were compensated for in virtually all the cases. Good results were obtained for the four emission lines taken as internal standards (i.e., Mg 280.270, Co 228.616, Cr 205.552 and Cu 324.754). However, for acetic acid and a few lines, IS was not efficient for removing interferences. The methodology was validated by analyzing two reference solid samples of foods (i.e., bovine liver and mussel tissue). By using Cd 214.438 as internal standard and under discrete mode 100% recoveries were found. 2004-01-01T00:00:00Z http://hdl.handle.net/10045/2750 Título: Evaluation of several pneumatic micronebulizers with different designs for use in ICP–AES and ICP–MS. Future directions for further improvement Autor/es: Maestre Pérez, Salvador; Todolí Torró, José Luis; Mermet, Jean Michel Resumen: This paper reports characterization of the behavior of five pneumatic micronebulizers based on slightly different designs in inductively coupled plasma atomic-emission spectrometry and mass spectrometry (ICP–AES and ICP–MS). Two nebulizers were used as reference nebulizers, a high-efficiency nebulizer (HEN) and a micromist (MM). They were compared with a commercially available PFA (tetrafluoroethylene–per- fluoroalkyl vinyl ether copolymer) nebulizer and with two new prototypes called the polymeric pneumatic concentric nebulizer (PMN) and the high-solids micronebulizer (HSM). The dimensions of the nebulizers, the gas back-pressure, and the free liquid uptake rates were measured. The study also included tertiary aerosol dropsize distributions, analyte transport rate, and analytical figures of merit, i.e. sensitivities and limits of detection, both in ICP–AES and ICP–MS. Recoveries for two food solid reference materials were also determined. Overall, the results indicated that the PFA and the HEN nebulizers provided the best results. These two nebulizers delivered a higher mass of analyte to the plasma and showed better sensitivies giving lower limits of detection than the PMN, HSM and MM. The results revealed that the liquid prefilming effect occurring before aerosol production in the PFA nebulizer promoted more effi- cient interaction of liquid and gas, thus affording good results even though gas back-pressure values could be maintained below 3 bar. In contrast, the HEN had to be operated at about 7 bar under the same conditions. Nebulizer design did not have a relevant effect on the recovery, which confirmed that the spray chamber plays an important role in terms of non-spectroscopic interferences. 2004-07-01T00:00:00Z