Methods of Methods of Chemical AnalysisChemical Analysis

Selecting an Analytical Selecting an Analytical TechniqueTechnique

Organic vs. Inorganic materialsOrganic vs. Inorganic materials Organic: Organic: Inorganic:Inorganic:

Quantitative vs. Qualitative Quantitative vs. Qualitative determinationdetermination Must identify first then determine amountMust identify first then determine amount

ChromatographyChromatography

A means for separating and A means for separating and identifying organic mixtures into their identifying organic mixtures into their component parts by using their component parts by using their attraction to a attraction to a ________________________________ while being propelled through a while being propelled through a __________________________________

Types of ChromatographyTypes of Chromatography1.1. __________________________________________ : Used : Used

to identify inks and other dyes. The to identify inks and other dyes. The molecules will travel at different molecules will travel at different speeds as they are pulled along speeds as they are pulled along paper (stationary phase) by a paper (stationary phase) by a solvent (mobile phase). Thus solvent (mobile phase). Thus separating the mixture.separating the mixture.

http://chemscape.santafe.cc.fl.us/chemscape/catofp/chromato/paper/paper.htm#description

Paper ChromatographyPaper Chromatography

2. Gas Chromatography 2. Gas Chromatography (GC)(GC)

Separates mixtures on the basis of their Separates mixtures on the basis of their distribution between a stationary liquid distribution between a stationary liquid phase and a moving gas phase.phase and a moving gas phase.

Can separate highly complex mixtures Can separate highly complex mixtures within minuteswithin minutes Carrier Gas: moving phaseCarrier Gas: moving phase Packed or Capillary Column: Heated Packed or Capillary Column: Heated

thin layer of liquid contained within thin layer of liquid contained within columncolumn

Gas ChromatographyGas Chromatography

Gas Chromatography Gas Chromatography cont…cont…

Pyrolysis GCPyrolysis GC : :

Pyrolysis: Pyrolysis:

Pyrogram:Pyrogram:

3. High Performance Liquid 3. High Performance Liquid Chromatography (HPLC)Chromatography (HPLC)

Moving phase is a liquid that is pumped Moving phase is a liquid that is pumped over chemically treated solid particles over chemically treated solid particles (stationary phase). The liquid carries the (stationary phase). The liquid carries the sample over the particles and they sample over the particles and they ““stickstick”” to particles at different spotsto particles at different spots

Performed at room tempPerformed at room temp Used for Used for

HPLCHPLC

HPLCHPLC

HPLCHPLC

4. Thin Layer 4. Thin Layer Chromatography (TLC)Chromatography (TLC)

Thin Layer Plate: Thin Layer Plate:

Sample will separate out as moves up Sample will separate out as moves up gel plategel plate

TLC ChromatogramTLC Chromatogram

5. Electrophoresis5. Electrophoresis

Separation of molecules through their Separation of molecules through their migration on a gel medium migration on a gel medium

Materials are pulled through by electric Materials are pulled through by electric charge of samplecharge of sample

Used for characterization ofUsed for characterization of

ElectrophoresisElectrophoresis

ElectrophoresisElectrophoresis

ElectrophoresisElectrophoresis

SpectrophotometrySpectrophotometry

Analytical method for identifying a Analytical method for identifying a substance by substance by

Instrument used to measure and record Instrument used to measure and record absorption spectrum of a chemical absorption spectrum of a chemical substancesubstance

Relates to the Relates to the amount of substanceamount of substance Variety of types:Variety of types:

Mass SpectrometerMass SpectrometerMass SpecMass Spec: Identifies and Measures the : Identifies and Measures the

amount of substance found in a sampleamount of substance found in a sample Computer AttachedComputer Attached: records, stores and : records, stores and

compares large amounts of data with a compares large amounts of data with a mass spectra librarymass spectra library

Important for analyzing:Important for analyzing: Samples must be pureSamples must be pure

So what do you do first?So what do you do first?

Mass SpectrometerMass Spectrometer

Mass SpectrometryMass Spectrometry

Mass SpectrometryMass Spectrometry

Mass SpecMass Spec

Inorganic AnalysisInorganic Analysis Important Instrumentation for determining the Important Instrumentation for determining the

components of:components of:

Example: Kennedy Assassination Example: Kennedy Assassination The analysis of the bullet contents leads to some puzzling The analysis of the bullet contents leads to some puzzling

questionsquestions http://www.edwardjayepstein.com/archived/state.htm

Atomic Absorption SpectrophotometerAtomic Absorption Spectrophotometer::-Detects -Detects trace elementstrace elements -Also useful for establishing the source of materials in -Also useful for establishing the source of materials in evidenceevidence

Absorption & Emission SpectraAbsorption & Emission Spectra

Neutron Activation AnalysisNeutron Activation Analysis

Provides a nondestructive method of identifying Provides a nondestructive method of identifying and quantifying trace elements most sensitive and quantifying trace elements most sensitive method for quantifyingmethod for quantifying InvolvesInvolves

Can simultaneously analyze 20-30 elementsCan simultaneously analyze 20-30 elements Extremely expensive – sophisticated method needs Extremely expensive – sophisticated method needs

a lot of training (can you guess why?)a lot of training (can you guess why?) Used for analyzingUsed for analyzing

Neutron ActivationNeutron Activation

X- Ray DiffractionX- Ray Diffraction

Aiming a beam of X-rays at crystals Aiming a beam of X-rays at crystals reveals a diffraction pattern. reveals a diffraction pattern.

Every compound produces its own Every compound produces its own unique patternunique pattern

Used forUsed for

Comparison of X- Ray Comparison of X- Ray Diffraction PatternsDiffraction Patterns

Ugh…. Ugh…. Glad that one is over. Glad that one is over. Do you think they are?Do you think they are?