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Chem. 133 3

Announcements. Quiz TodayTerm Project Proposal due TodayFriday's Seminar: James Chan (UC Davis Medical School), Non-invasive Single Cell Cytometry Using Label-Free Biophotonic Techniques"Today's LectureAtomic SpectroscopyAtomic Absorption Interferences Methods to DecreaseAtomic Emission

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Chem. 133 3

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    1. Chem. 133 – 3/15 Lecture

    2. Announcements Quiz Today Term Project Proposal due Today Friday’s Seminar: James Chan (UC Davis Medical School), “Non-invasive Single Cell Cytometry Using Label-Free Biophotonic Techniques” Today’s Lecture Atomic Spectroscopy Atomic Absorption – Interferences + Methods to Decrease Atomic Emission Spectrometers NMR (Overview + Theory)

    3. Atomic Spectroscopy Interference in Absorption Measurements Spectral Interferences (covered last time) Chemical Interference Arises from compounds in sample matrix or atomization conditions that affects element atomization Some examples of specific problems (mentioned previously) and solutions: Poor nebulization (e.g. viscous liquid) – dilute or change nebulizer Poor volatility due to PO43- – add Ca because it binds strongly to PO43- allowing analyte metal to volatilize better or use hotter flames Formation of metal oxides and hydroxides – use fuel rich flame Ionization of analyte atoms – add more readily ionizable metal (e.g Cs) Another approach is to use a standard addition calibration procedure (this won’t improve atomization but it accounts for it so that results are reliable)

    4. Atomic Spectroscopy Interference in Absorption Measurements Standard Addition Used when sample matrix affects response to analytes Commonly needed for AAS with complicated samples Standard is added to sample (usually in multiple increments) Needed if slope is affected by matrix Concentration is determined by extrapolation (= |X-intercept|)

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