L19 - Lecture19 MassSpecApplicationsII LCMS/MS LCMS/MS

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Lecture 19 Mass Spec Applications II
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LC MS/MS
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LC MS/MS LC MS/MS has a triple quadrupole mass analyzer (low resolution) Ion Sources Electrospray Ionization (ESI)–soft ionization technique, multiple charges possible, analyte must be capable of being charged in liquid state, adduct formation possible, ion suppression possible Atmospheric Pressure Chemical Ionization (APCI)–not as soft as ESI, usually results in a single charge, ionization takes place in the gas phase, amenable to higher LC flow rates
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LC MS/MS •Tr ip le quad common for LC applications : matrix effects! •LC MS/MS offers almost unparalleled sensitivity for trace level analysis of non volatiles •S trong vacuum pumps required, power requirements obscene
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LC MS/MS Young et al. 2007. “Perfluorinated acids in arctic snow: new evidence from atmospheric formation” Environ. Sci. Technol. 41:3455 3461. •Perfluorinated acids quantified in Arctic ice caps using LC MS/MS with negative electrospray ionization (why?) •Could these be analyzed by GC MS? What additional steps are needed (if any)? F F F F F F F F F F O - F F O F F F F F F F F F F F F F S O - F F F F F F F O O PFOS PFOA
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The Perfluorinated Story •P e r f l u o r i n a t e d acids ubiquitously in the environment, biotically and abiotically • Question: How do non volatile deprotonated acids reach remote areas? • Two schools of thought 1) Acids transported in marine water to remote regions 2) Commercially used “precursor” compounds are transported atmospherically to remote areas, then degraded to the acids F F F F F F F F F F OH F F F F F F F F F F F F F F F F F O - F F O F F F PFOA Fluorotelomer Alcohol
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L19 - Lecture19 MassSpecApplicationsII LCMS/MS LCMS/MS

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