Departamento de Química Física y Analítica
URI permanente para esta comunidadhttps://hdl.handle.net/10953/49
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Examinando Departamento de Química Física y Analítica por Materia "Ambient mass spectrometry"
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Ítem Ambient Diode Laser Desorption Dielectric Barrier Discharge Ionization Mass Spectrometry of Nonvolatile Chemicals(ACS Publications, 2013-02-19) Gilbert-López, Bienvenida; Schilling, Michael; Alhmann, Norman; Michels, Antje; Hayen, Heiko; Molina-Díaz, Antonio; García-Reyes, Juan Francisco; Franzke, JoachimIn this work, the combined use of desorption by a continuous wave near-infrared diode laser and ionization by a dielectric barrier discharge-based probe (laser desorption dielectric barrier discharge ionization mass spectrometry (LD-DBDI-MS)) is presented as an ambient ionization method for the mass spectrometric detection of nonvolatile chemicals on surfaces. A separation of desorption and ionization processes could be verified. The use of the diode laser is motivated by its low cost, ease of use, and small size. To achieve an efficient desorption, the glass substrates are coated at the back side with a black point (target point, where the sample is deposited) in order to absorb the energy offered by the diode laser radiation. Subsequent ionization is accomplished by a helium plasmajet generated in the dielectric barrier discharge source. Examples on the application of this approach are shown in both positive and negative ionization modes. A wide variety of multiclass species with low vapor pressure were tested including pesticides, pharmaceuticals and explosives (reserpine, roxithromycin, propazine, prochloraz, spinosad, ampicillin, dicloxacillin, enrofloxacin, tetracycline, oxytetracycline, erythromycin, spinosad, cyclo-1,3,5,7-tetramethylene tetranitrate (HMX), and cyclo-1,3,5-trimethylene trinitramine (RDX)). A comparative evaluation revealed that the use of the laser is advantageous, compared to just heating the substrate surface.Ítem Direct analysis of olive oil and other vegetable oils by mass spectrometry: a review(Elsevier) Beneito-Cambra, Miriam; Moreno-González, David; García-Reyes, Juan Francisco; Bouza, Marcos; Gilbert-López, Bienvenida; Molina-Díaz, AntonioVirgin olive oil (VOO) is a highly valued vegetable oil often subjected to fraud practices such as adulteration with lower prized oils such as seed oils and refined olive oil. Thus, there is a need to provide rapid tools that allow high-throughput authentication and quality control of VOO as well as other valued oils. Mass spectrometry offers unique features -such as specificity, sensitivity and speed of analysis-that map well against this challenge, either those based on atmospheric pressure ionization methods (ESI and APCI) or those occurring under vacuum conditions such as MALDI for nonvolatile species or headspace sampling-mass spectrometry using electron impact ionization (HS-MS) or chemical ionization (proton transfer reaction mass spectrometry (PTR-MS) and selected ion flow tube mass spectrometry (SIFT-MS)) for volatile fraction analysis. In addition, more recent atmospheric pressure methods (Ambient MS) enable direct analysis with minor or even no sample manipulation. The aim of this article is to provide a critical overview on all these methods and their potential use for vegetable oil characterization, highlighting the strengths and weaknesses of the different