Solid phase micro-extraction in a miniature ion trap mass spectrometer

Fiber introduction mass spectrometry (FIMS), a variation of solid-phase microextraction (SPME) and membrane introduction mass spectrometry (MIMS), is employed with a miniature mass spectrometer. The inlet system, constructed of commercially available vacuum parts, allows the direct introduction of the SPME needle vacuum chamber into the mass spectrometer. Thermal desorption of the analyte from the poly(dimethylsiloxane) (PDMS) coated fiber was achieved with a built in nichrome heater, followed by electron ionization of the analytes internal to the cylindrical ion trap (CIT). The system has been tested with several volatile organic compounds (VOC) in air and to analyze the headspace over aqueous solutions, with limits of detection in the low ppb range. The signal rise (10-90%) and fall (90-10%) times for the system ranged from 0.1 to 1 s (rise) and 1.2 to 6 s (fall) using heated desorption. In addition, this method has been applied to quantitation of toluene in benzene, toluene, xylene (BTX) mixtures in water and gasoline. This simple and rapid analysis method, coupled to a portable mass spectrometer, has been shown to provide a robust, simple, rapid, reproducible, accurate and sensitive (low ppb range) fieldable approach to the effective in situ analysis of VOC in various matrices.12891119112

Collision of millimetre droplets induces DNA and protein transfection into cells

Nonperturbing and simple transfection methods are important for modern techniques used in biotechnology. Recently, we reported that electrospraying can be applied to DNA transfection in cell lines, bacteria, and chicken embryos. However, the transfection efficiency was only about 2%. To improve the transfection rate, physical properties of the sprayed droplets were studied in different variations of the method. We describe a highly efficient technique (30–93%) for introduction of materials such as DNA and protein into living cells by electrospraying droplets of a high conductivity liquid onto cells incubated with the material for transfection. Electric conductivity has a sizable influence on the success of transfection. In contrast, molecular weight of the transfected material, types of ions in the electrospray solution, and the osmotic pressure do not influence transfection efficiency. The physical analysis revealed that collision of cells with millimetre-sized droplets activates intracellular uptake

Semi-quantitative analyses of metabolic systems of human colon cancer metastatic xenografts in livers of superimmunodeficient NOG mice

Analyses of energy metabolism in human cancer have been difficult because of rapid turnover of the metabolites and difficulties in reducing time for collecting clinical samples under surgical procedures. Utilization of xenograft transplantation of human-derived colon cancer HCT116 cells in spleens of superimmunodeficient NOD/SCID/IL-2Rγnull (NOG) mice led us to establish an experimental model of hepatic micrometastasis of the solid tumor, whereby analyses of the tissue sections collected by snap-frozen procedures through newly developed microscopic imaging mass spectrometry (MIMS) revealed distinct spatial distribution of a variety of metabolites. To perform intergroup comparison of the signal intensities of metabolites among different tissue sections collected from mice in fed states, we combined matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI–TOF-IMS) and capillary electrophoresis–mass spectrometry (CE–MS), to determine the apparent contents of individual metabolites in serial tissue sections. The results indicated significant elevation of ATP and energy charge in both metastases and the parenchyma of the tumor-bearing livers. To note were significant increases in UDP-N-acetyl hexosamines, and reduced and oxidized forms of glutathione in the metastatic foci versus the liver parenchyma. These findings thus provided a potentially important method for characterizing the properties of metabolic systems of human-derived cancer and the host tissues in vivo

Advances in structure elucidation of small molecules using mass spectrometry

The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules

Novel CFCs-substitutes recommended by EPA (hydrofluorocarbon-245fa and hydrofluoroether-7100): Ion chemistry in air plasma and reactions with atmospheric ions

The ion chemistry of the title compounds, a nonafluorobutyl methyl ether and a hydrofluoropropane, is elucidated by a combination of studies using atmospheric pressure ionization mass spectrometry and triple quadrupole mass spectrometry. In the positive ion mode, the hydrofluoroether readily forms an [M - F](+) ion, attributable to hydronium ion induced dehydrofluorination, the product of which can be further hydrated to give a protonated hydrofluoroester. By contrast, the hydrofluoropropane does not react with the hydronium ion but rather gives hydrofluoroalkenylium cations via H atom and F atom abstraction by the dioxygen radical cation. In the negative ion mode, the fluorobutyl methyl ether undergoes dissociative electron capture with O-2(-.), O-2(-.) (H2O), O-3(-) and NO2- to generate the fluorobutoxy anion, which can dissociate by CF2=O loss to give the perfluorocarbanion when the precursor ions are internally excited. The hydrofluoropropane reacts readily with common atmospheric anions to form molecular complexes with F-, O-2(-.), and O-3(-.) and the strongly H-bonded species, O-2(-.)(HF) and F-(HF). Interestingly, isomeric pentafluoropropanes form in the reaction with O-2(-.), either O-2(-.)(HF) or F-(HF), depending on the specific pattern of the fluoro substitution

Determination of Brain Extracted Lipids by Thin-Layer Chromatography – Imaging Desorption Electrospray Ionization (TLC-Imaging DESI).

En este artículo se narra la reforma llevada a cabo desde 1994 en adelante en la estructura y el funcionamiento del hospital Luis Calvo Mackenna, centro asistencial pediátrico de nivel terciario perteneciente al Servicio de Salud Metropolitano Oriente, de Santiago, Chile. Se refieren brevemente los antecedentes de la formación del sistema de salud de Chile, los cambios traídos por el gobierno militar en 1979 y otras transformaciones debidas al primer gobierno democrático en 1990 y al segundo, establecido en 1994. A pesar de los buenos indicadores de salud de Chile y del deseo del gobierno actual de establecer equidad en los servicios y poner en marcha un sistema descentralizado, el sistema de salud modelado fundamentalmente en los decenios de 1950 y 1960 no ha podido hacer frente a los cambios causados por la transición demográfica y el nuevo perfil epidemiológico de la población. Uno de los grandes problemas es que los niveles secundario y terciario de atención no tienen la capacidad necesaria para responder a la demanda. Bajo una nueva dirección interesada en métodos contemporáneos de gestión, en el hospital Luis Calvo Mackenna se reestructuraron los servicios clínicos con nuevos departamentos y unidades, se llevó a cabo un estudio del clima organizacional, se capacitó intensivamente a todo el personal para inculcarle el espíritu de participación y una nueva visión de la misión del hospital y del trabajo en equipo, y se formuló un plan estratégico que todavía se está cumpliendo.<br>This article discusses the structural and operational reform process that took place beginning in 1994 in Luis Calvo Mackenna Hospital, a tertiary pediatric care facility run by Oriente Metropolitan Health Center in Santiago, Chile. The formation of the Chilean health care system is briefly outlined, along with the changes brought about by the military government in 1979 and other transformations introduced by the first democratic government in 1990 and by the second one, in 1994. In spite of Chile's favorable health indicators and of the current government's desire to establish equitable services and to launch a decentralized system, the health care system that was fundamentally modeled in the fifties and sixties has failed to respond successfully to the demographic transition and to the population's new epidemiologic profile. One of the main problems is that services at the secondary and tertiary levels lack what is necessary to respond to the demand. Under a new leadership with an interest in modern administrative methods, clinical services at Luis Calvo Mackenna Hospital were restructured with new departments and units, a study of the organizational climate was carried out, the entire staff was intensively trained so as to generate a spirit of involvement and a new vision of the hospital's mission and teamwork, and a strategic plan was drawn up that is still being implemented