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A survey of selected principles and techniques of modern analytical chemistry with a focus on major areas including spectroscopy, separations sciences, and electroanalytical chemistry. Some key points from this lecture are: Gc and Sfc, Introduction to Analytical Chemistry, Role of Analytical Chemistry, Analytical Methods, Spectroscopic Techniques, Electrochemical Techniques, Microscopic and Surface Techniques, Qualitative Molecular Information, High Pressure Liquid Chromatography, Nuclear Magnet
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They adapt proven methodologies to new materials/systems or to answernew questions about their composition.Analytical chemists work to improve existing techniques to meet thedemands of for faster, cheaper, more sensitive chemical measurementsAnalytical chemists research to completely new types of measurementsand are at the forefront of the utilization of major discoveries in fields asdiverse as photonics and implantable microchip sensors.Analytical chemistry is applied to many branches of science
MedicineIndustry Environmental Food and Agriculture
ForensicsArchaeology Space science
The Role of Analytical Chemistry
Spectroscopic techniques
Infrared spectrometryRaman spectrometryNuclear magnetic resonance (NMR)X-ray spectrometryAtomic absorption spectrometryInductively coupled plasma atomic emission spectrometryInductively coupled plasma MSAtomic fluorescence spectrometryUltraviolet/visible spectrometry (CD)Molecular fluorescence spectrometryChemiluminescence spectrometryX-Ray Fluorescence spectrometry
Electrochemical techniques
AmperometryVoltammetryPotentiometryConductiometry
Microscopic and surface techniques
Atomic force microscopyScanning tunneling microscopyAuger electron spectrometryX-ray photon electron spectrometry
1. Understanding and Defining
the Problem
History of sample and background
of the problem
Analysis type
Quantitative, Qualitative
Location of sample
bulk or surface
Physical state of sample
gas, liquid, solid, dissolved solid, dissolved gas
Amount of Sample
macro, micro, nano, …
Fate of sample
destructive, non destructive
Estimated purity of sample
pure, simple mixture, complex mixture
Analyte concentration
major or minor component, trace or ultra trace
Elemental information
total analysis, speciation, isotopic and mass analysis
Qualitative Molecular information
compounds present, polyatomic ionic species, functionalgroup, structure, molecular weight, physical property
HPLC
NMR
Location of sample
bulk or surface
B^
B
Physical state of sample
gas, liquid, solid, dissolved solid, dissolved gas
L,Ds
L,S,Ds
Amount of Sample
macro, micro
Ma, Mi
Ma, Mi
Estimated purity of sample
pure, simple mixture, complex mixture
Sm,M
P,Sm
Fate of sample
destructive, non destructive
N,D
N
Elemental information
total analysis, speciation, isotopic and mass analysis
Molecular information
Compounds present, Polyatomic ionic species,
Cp,Io,St
Cp,Fn,St
Functional group, Structural, MW, Physical prop
Analysis type
Quantitative, Qualitative
Ql,Qt
Ql,Qt
T,S (ion)
limited
3. Analyzing Data and Reporting Results - Analytical data analysis takes many forms: statistics,
See pg. 967 of Skoog et al.,
Principles of Instrumental Analysis
, Thomson Brooks/Cole, New York, 2007.
Precise, not accurate
Accurate, not precise
Accurate and precise
Limit of detection (LOD): the lowestamount of an analyte that can bedetected at a known confidence level
Signal-to-noise:
ratio of the average
signal to the average level of noise.
Limit of quantitation (LOQ): the rangeover which quantitative measurementscan be made (usually the linear range),often defined by detector dynamicrange
Linearity: the degree to which a response of an analytical detector toanalyte concentration/mass approximates a linear function
Dynamic range: range between the LOQ and limit of linearity
Concentration
Detector response
LOQ LOD
Limit of linearity
Slope relates to
sensitivity
Dynamic range
Basis Quantitative Analysis
Significant Figures
^
All nonzero digits are significant:
^
1.234 g has 4 significant figures
^
Zeroes between nonzero digits are significant:
^
1002 kg has 4 significant figures
^
Leading zeros to the left of the first nonzero digits are not significant;such zeroes merely indicate the position of the decimal point:
^
o C has only 1 significant figure
^
Trailing zeroes that are also to the right of a decimal point in a numberare significant:
^
0.0230 mL has 3 significant figures
^
When a number ends in zeroes that are not to the right of a decimalpoint, the zeroes are not necessarily significant:
^
190 miles may be 2 or 3 significant figures
Prefixes for SI Units giga-
9
mega-
6
kilo-
k^
3
deci-
d^
centi-
c^
milli-
m
micro-
μ^
nano-
n^
pico-
p^
femto-
f^
atto-
a^
Scientific Notation and Prefixes
^6
Moles of solute / L
= mass of solute
6
ppm
mass of solution
For dilute aqueous solutions whose densities are approximately 1.00g/mL
1 ppm = 1 mg/L =1 μg/mL
= mass of solute
9
ppb
or
1 μg/L
mass of solution
Working with Numbers: Analytical
Concentrations
