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Chem415Quantitative Bio-Element

Imaging Center (QBIC): Part I

APRIL 10, 2015

DIRECTOR: PROFESSOR THOMAS V. O’HALLORAN

MANAGING DIRECTOR: KEITH MACRENARIS, PH.D

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History and Mission of CLP and QBIC

“The Chemistry of Life Processes Institute acts as an umbrella for a variety of centers, facilitates collaborations and helps bridge different cultures. By lowering the barriers to scientific discovery, the Institute hopes, for example, to design new drugs for the treatment of cancer and neurodegenerative diseases as well as develop improved techniques for diagnosing diseases earlier.”

Designed to be a collaborative, interdisciplinary effort to map the “inorganic signatures of life”

Started in 2003 and established as an official center within the Chemistry of Life Processes Institute in September of 2008

CLP includes 39 tenure-track faculty members and 11 cores and centers

Elemental Analysis is located in Silverman Hall East Room B540

Microscopy is located in Silverman Hall East room 1567

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How to Map the Inorganic Signatures of Life

Elemental Analysis

Using high end instrumentation for quantitative metal analysis to determine metal concentrations in solutions, materials, cells and tissues.

ImagingUsing one-of-a-kind STEM, 2-photon laser scanning microscopy, and laser ablation ICP-MS for elemental mapping in tissues and cells

CollaborationThe synergy with Argonne National Laboratory and the Advanced Photon Source for Hard X-ray Fluorescence Microscopy for subcellular trace elemental mapping

4Emission Ratiometric Imaging of Intracellular Zinc

J. Am. Chem. Soc., 2004, 126 (3), pp 712–713

Excitation @ 710 nm using 2-photon laser

No treatment

+ 10 µM zinc sulfate + 1 mM TPEN

5Choosing the Correct Analytical Technique I

6Choosing the Correct Analytical Technique II

7Atomic Absorption Spectroscopy Quantitative determination

using absorption of optical radiation (light) by free atoms in the gaseous state.

Electrons of the atom can be promoted to higher orbitals by absorbing radiation of a given wavelength (specific to an electron transition of a particular element).

The radiation flux with and without a sample in the atomizer is measured using a detector resulting in absorbance at a particular wavelength.

8Flame Atomic Absorption Spectroscopy (Flame AA or AAS)

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Flame AA in QBIC

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Lamp Types for AAS

Hollow Cathode Lamps

Electrodeless Discharge Lamps

11Graphite Furnace(Electrothermal) Atomic Absorption

Major limitation for flame AA is burner-nebulizer system is relatively inefficient so only a small fraction of the sample reaches the flame where the atomized sample passes quickly through the light path.

Improved sampling device would atomize the entire sample in the light path for an extended period of time enhancing the sensitivity of the techniques

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Steps in Atomic Absorption

Flame AAS Desolvation (drying) – solvent is

evaporated and dry sample nano-particles remain

Vaporization (transfer to gaseous phase) – solid particles are converted into gaseous molecules

Atomization – molecules are dissociated into free atoms

Ionization – Atoms may be converted to gaseous ions (not necessary for analysis)

GFAAS Desolvation (drying) – solvent is

evaporated and dry sample nano-particles remain

Pyrolysis – Majority of the matrix components are removed

Atomization – Analyte element is released into the gaseous phase

Cleaning – Residue in the graphite tube is removed at high temperatures

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Uses of Atomic Absorption

Flame AA is becoming rarer due to the lower cost of purchase and operation of more advanced analytical techniques (i.e. GFAAS and ICP)

GFAAS has been an established techniques for more than 40 years especially in the food industry and for clinical samples

Many EPA and FDA analytical methods are approved using GFAAS

GFAAS very useful for samples with very limited volumes (< 100 µL)

14Choosing the Correct Analytical Technique III

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Analytical Advantages of ICP over AA?

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Information

For elemental analysis email: Keith MacRenaris at keithmacrenaris2009@u.northwestern.edu

For STEM/EDS analysis email: Reiner Bleher at bleherreiner@gmail.com

QBIC website: http://qbic.facilities.northwestern.edu/

NUANCE website: http://www.nuance.northwestern.edu/