Chem415 Quantitative Bio-Element Imaging Center (QBIC): Part II

Chem415 Quantitative Bio-Element Imaging Center (QBIC): Part II www.phwiki.com

Chem415 Quantitative Bio-Element Imaging Center (QBIC): Part II

Higgins, Polly, Metro Mix Editor has reference to this Academic Journal, PHwiki organized this Journal Chem415 Quantitative Bio-Element Imaging Center (QBIC): Part IIApril 13, 2015Director: Professor Thomas V. O’HalloranManaging Director: Keith MacRenaris, Ph.D1Analytical Advantages of ICP over AA2ICP is The Choice as long as Multi-Element Analysis3

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Component Breakdown of ICPFront End IntegrationFor Liquid Samples: autosamplers coupled to peristaltic pumpsFor Separations/Speciation Analysis: Systems can be designed with GC, HPLC, IC or CE prior to integration into the ICPFor Imaging: Laser ablation units can be integrate as long as quantitative elemental imaging/mapping Sample IntroductionNebuliser – Need to produce a fine mist as long as efficient sample introduction – Usually made of quartz or PFA – concentric, self-aspirating, in addition to cross-flow Spray Chambers – Need to discern between large in addition to small droplets from the nebulizer prior to introduction into the plasma torch – bead impact, cyclonicPlasma TorchMore efficient in addition to reproducible vaporization, atomization, excitation, in addition to ionization due to high temperatures of the plasma 6000 K – 10000 K versus 3300 K as long as flames in addition to furnacesUses mainly argon as carrier gas an torch source so low noise or contamination due to electrode materials required in Flame AA or GFAASDetectionOptical Emission Spectrometer – Usually a echelle polychromator in addition to CCD, CID, or CMOS detector chipsMass Spectrometer – Quadropole, Magnetic Sector Field, or Orbitrap with pulse counting in addition to analog detectors4Autosampler/Peristaltic PumpAutosamplers: Usually come in a variety of configurations with multiple rack typesPeristaltic Pumps are typically used due to low cost in addition to consistency2 issues with peristaltic pumps: 1) with ICP-MS you have to average out the peristalsis. 2) sample contamination of tubing is difficult to remove (also known as memory artifacts)Newer valve/syringe assemblies allow as long as auto-dilution in addition to decrease uptake in addition to washout times while increasing accuracy in addition to precisionEven using new valve in addition to syringe-driven autosampling peristaltic pumps are still required as long as waste in addition to washout5NebulizersNebulizers use 2 priniciple to create a fine mist as long as sampling: 1) Venturi effect whereby a fluid’s velocity must increase as it passes through a constriction2) Pneumatic Induction whereby a gas is used as the driving as long as ce to convert a liquid into a fine sprayThe main types of nebulizers used are concentric in addition to burgener or enhanced parallel path nebulizers (usually as long as Highly corrosive samples such as HF)6

Spray ChambersPurpose of a Spray Chamber is to remove droplets produced by the nebulizer that are > 8 µm in diameter, smooth out pulses produced by the peristaltic pump, in addition to if cooled keep the sample thermally stableTwo main types are double-pass in addition to cyclonic spray chambersUse correct material in addition to choose proper design as long as particular sample types 7Plasma TorchWant to increase energy as long as more efficient atomization in addition to ionizationICP torches as long as m the plasma by a tangential stream of argon gas flowing between 2 quartz tubes followed by pulsing AC of RF power through the coil producing an oscillating magnetic field (27.12 MHz usually)An electric spark is applied to introduce free electrons into the gas stream which are then accelerated by the rapidly changing magnetic fieldAccelerated electrons collide with argon atoms as long as cing the loss of an electron which in turn accelerate in the oscillating magnetic fieldResults in multiple temperature zones within the produced plasma8ICP-OES OpticsAfter sample passes through the plasma the atom is allowed to drop from a high energy state back to the ground state through emission of a photonThese photons are analyzed through a monchromator in addition to echelle grating be as long as e hitting the detectorAllows readouts in 2 dimensions providing better resolution in addition to faster analysis than old PMT methodsCan get full spectrum analysis as long as every sample (called full frame capture)9

ICP-OES: Axial versus Radial ViewingRadial View: Off-axis plasma viewing provides highest upper linear ranges (~ 100 pm or greater depending upon intensity of spectral line)Axial View: Views the light looking down the center of the torch providing better detection limits than radial view by up to 10-foldDual View: Allows viewing in both axes Radial viewing is accomplished through a hole in the plasma torch allowing as long as faster transitions between axial in addition to radial views (shorter run times) 10Advantages in addition to Disadvantages as long as ICP-OESAdvantagesDue to high temperature of ICP plasma most species are broken into atoms or ions as long as excitation in addition to subsequent emissionOf all analytical atomic spectrometry techniques has the fewest interferencesCan tolerate up to 20%-30% TDSMulti-element capability due to CCD/CID chips DisadvantagesProne to spectral interferencesEasily-ionize-element (EIE) effect – happens with elements with low ionization potentials such as alkaline elements which can suppress or enhance emission signalsDoes not provide ultra-trace or real-time analysisDoes not provide in as long as mation about the different naturally occurring isotopes of a particular element11ICP-MSICP-OES was commercialized in 1974, whereas ICP-MS wasn’t commercialize until 1983Use Mass Spectrometer to analyze samples due to atomization in addition to more importantly ionization of elements in the plasmaSingly charged ions are being detected according to there mass-to-charge ratioHave to get the system into a low vacuum state between 10-5 to 10-7 Torr which is accomplished using a sample in addition to skimmer cone interface12

ICP-MS Detection: Cones13Sample ConeSkimmer ConeCones are generally made out of Ni: Robust, minimal interferences, tolerate high matrix, relatively long-lasting in addition to realtively low costCan be made out of platinum: More resistant to corrosion, longer lasting, no Ni interference, cost 5-10 times more than Ni conesHelps restrict the amount of sample going into the ion lenses in addition to quadrupole in addition to helps decrease the pressure incrementallyICP-MS Detection: Lens StackPositioned between the skimmer cone in addition to mass separation deviceConsisting of multiple electrostatically controlled lens componentsSteer the ions from the hostile environment of the plasma at atmospheric pressure in addition to steer them into the mass analyzer at high vacuumIons with high kinetic energy will be transmitted in preference to ions with medium or low kinetic energyRecent advancements have led to the design of a 90° lens prior to entry into the KED/CCT reaction cell or quadrupole14Quadrupole Mass AnalyzerUsing a quadrupole mass analyzer consisting of 4 rods that are 15-20 cm in lengthPlace a direct current on one pair of rods in addition to a radio frequency field on the opposite pair ions of a selected mass are allowed to pass through to the detector while the others are ejected from the quadrupoleIn the example 63Cu is repeatedely scanned as electrical pulses are stroed in addition to counted by a multichannel analyzerScan rates are typically 2500 amu per second in addition to can cove the entire mass range of 0-300 amu in about 0.1 s15

Mass InterferencesCommon interferences are argides, oxides, in addition to chlorideCollision cell in addition to reaction cell technology were developed to h in addition to le major mass interferencesAnother solution is as long as high resolution magnetic sector field ICP-MS which is cost prohibitive16Advantages in addition to Disadvantages as long as ICP-MSAdvantagesDue to high temperature of ICP plasma most species are broken into atoms or ions as long as excitation in addition to subsequent emissionLow level detection down to pptIsotope abundance determinationLarge linear range due to multiple detectors PC in addition to analogDisadvantagesProne to mass interferencesLow tolerance as long as TDS usually < 0.5%Difficult to analyze complicated matricesMore maintenance in addition to associated cost17Laser Ablation ICP-MS18 In as long as mationFor Microscopy in addition to LA-ICP-MS email: Keith MacRenaris at keithmacrenaris2009@u.northwestern.eduFor STEM/EDS analysis email: Reiner Bleher at bleherreiner@gmail.comQBIC website: http://qbic.facilities.northwestern.edu/NUANCE website: http://www.nuance.northwestern.edu/ Higgins, Polly Tucson Citizen Metro Mix Editor www.phwiki.com

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