ANACHEM LEC Flashcards
is the determination
of elemental composition by its
electromagnetic or mass spectrum
ATOMIC SPECTROSCOPY
When an atom is excited, its electrons
move to ____________ energy levels or orbits.
higher
When an electron transitions, it
releases energy in the form of __________________________
electromagnetic radiation
This is the process of converting a sample into gas-phase
atoms and ions for analysis.
ATOMIZATION
These introduce the sample in a steady, continuous stream
CONTINUOUS ATOMIZERS
These introduce individual samples one at a time using a syringe or autosampler.
DISCRETE ATOMIZERS
Examples for CONTINUOUS ATOMIZERS
Plasma
Flame
Examples for DISCRETE ATOMIZERS
Electrothermal Atomizers
A nebulizer creates an aerosol (fine spray) of the sample, which is introduced into a flame or plasma.
Direct Nebulization
A plug of sample is introduced with varying concentration over time.
Flow Injection and Liquid Chromatography:
An aliquot of the sample is introduced to the atomizer.
Direct Solution Samples
is a technique used to analyze
the elements present in a sample.
In this principle the analyte atoms are excited by heat or electrical energy.
ATOMIC EMISSION SPECTOMETRY
Each element emits light at specific
wavelengths, so by measuring the
wavelengths of light emitted by the sample,
we can identify which elements are present
and how much of each element is in the
sample.
ATOMIC EMISSION SPECTOMETRY
transition to or from the ground state
resonance transition
This method involves exposing atomic vapors of an
element to UV-VIS radiation, matching the
element’s characteristic frequency. The absorbed
radiation excites electrons from the ground state to
an excited level, reducing radiation intensity. By
measuring this absorption, we can determine the
concentration of atoms in the ground state, typically
in the UV-VIS region of the spectrum.
ATOMIC ABSORPTION SPECTOMETRY
Light source - Excitation monochromator - Sample holder - Emission monochromator- Detector- Readout device.
ATOMIC FLUORESCENCE SPECTOMETRY
allows for the detection and
quantification of trace components in environmental samples, making it
easier to meet regulatory criteria and monitor the environment.
ATOMIC FLUORESCENCE SPECTOMETRY
an analytical chemistry technique that helps identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions.
ATOMIC MASS SPECTROMETRY
the process of converting a sample into
individual atoms or atomic ions.
ATOMIZATION
Separating the ions formed in step 2 on the basis of
their mass-to-charge ratio (m/z), where m is the
mass number of the ion and z is the number of
fundamental charges that it bears
SEPARATION
Conversion of a substantial fraction of the
atoms formed in step 1 to a stream of ions
(usually singly charged positive ions);
ATOMS TO POSITIVE IONS
Counting the number of ions of each type or
measuring the ion current produced when the
ions formed from the sample strike a suitable
transducer
NUMBER OF IONS FORMED
the percentage of atoms with a specific
atomic mass found in a naturally occurring
sample of an element; can be determined
using mass spectrometry.
RELATIVE ABUNDANCE OF AN ISOTOPE
a weighted average calculated by
multiplying the relative abundances of the
element’s isotopes by their atomic masses
and then summing the products.
AVERAGE ATOMIC MASS OF AN ELEMENT
an instrument that produces ions and separates them according to their mass- to-charge ratios, m/z.
MASS SPECTROMETER
is a method used to separate substances within a
mixture. It uses a gas to carry the mixture
through a tube that is coated on the inside with
a liquid. Different substances in the mixture
move through this tube at different speeds,
which helps separate them from each other.
GAS-LIQUID CHROMATOGRAPHY
INSTRUMENTS OF GAS LIQUID CHROMATOGRAPHY
Carrier Gas Supply
Sample Injection System
Columns
Detectors
Thermal conductivity detector
Flame Ionization detector
Modified Flame ionization detector (FID)
Electron capture detector
Nitrogen Phosphorus Detector (NPD)
is the immobile part of the chromatographic system,
typically a coated layer inside a column, where the separation of compounds occurs based on their interaction with this phase.
Stationary phase
the stationary phase is a solid material coated onto the inside of the column.
Solid Stationary Phase
the stationary phase is a liquid that is coated onto a solid support inside the column.
Liquid Stationary Phase
carries the sample vapor through the column. The choice of carrier gas depends on factors such as the type of analysis being performed, the type of detector used, and the characteristics of the compounds being separated.
Mobile Phase
uses a single
material as both the support and stationary phase, like
silica or alumina, to retain chemicals based on their
sticking to the surface, with factors like surface area,
pore size, and functional groups influencing retention.
Gas-solid chromatography (GSC)
a form of
radiant energy that is propagated as a transverse
wave.
Electromagnetic Radiation
General Properties of EMR
Wave
Particle
The length of the electric vector at a maximum in the wave
Amplitude (A)
The time in seconds required for the passage successive maxima or minima through a fixed point in space
Period (p)
The number of oscillations of the field that occur per second and is equal to 1/p
Frequency (v)
The linear distance between any two equivalent points on successive waves
Wavelength (lambda) (λ)
The relationship between the wavelength and frequency
Velocity (V)
Velocity is determined as to be ____________________ m/s
2.99792x10^8 m/s
Equation for velocity
c=vλ
Velocity= Frequency x Wavelength\
The reciprocal of the wavelength in cm and is another way of describing electromagnetic radiation
Wavenumber (ṽ)
Formula for wavenumber
ṽ = 1/λ
FOrmula for energy of Photon
E= hv
Energy of Photon in J= Frequency of the EMR x Planck’s Constant
Equivalent for Planck’s Constant
6.626x 10^-34 J-sec
The ____________ the wavelength or the ______________ the frequency, the greater the energy.
shorter, greater
a. Light is absorbed by an atom, ion, or molecule,
taking it to a higher energy state
b. modes: rotational, vibrational, and electronic
Absorption
a. Release of a photon by an atom, ion or
molecule taking it to lower energy
Emission
a. Excitation of the analyte by a chemical reaction
b. may be fluorescense or phosphorescence
Chemiluminescence
a. Emission of photons is measured after
absorption
Photoluminescence
is commonly applied to
chemical analysis measurements to determine
the concentration of chemical species that
absorb light
Beer-Lambert Law
: Used for communication (e.g., radio and TV
broadcasts).
Radio Waves
Used in microwave ovens and communication
technologies.
Microwave
Associated with heat and used in thermal
imaging
Infrared Radiation
The range of wavelengths our eyes can perceive
Visible Light
Responsible for sunburn and used in sterilization.
Ultraviolet
Used in medical imaging and security screening.
X rays
High-energy radiation from nuclear processes.
Gamma Rays
is produced when charged particles (such as electrons) change their velocity
(accelerate or decelerate)
Electromagnetic Radiation
When an excited electron falls to a _______ energy level, it emits energy as _______________________________
lower, electromagnetic radiation
Show the distinct wavelengths that an object can emit. These occur when electrons in atoms transition to lower energy levels.
Emission Spectra
Indicate the wavelengths at which an object absorbs energy. Electrons absorb photons to move to higher energy levels.
Absorption Spectra
A study of how energy and radiated matter interact.
Spectrometry
Components of Optical Instrument
- Stable source of energy
- Wavelength Selector
- One or more sample containers
- Radiation detector
- Signal processing and readout unit
emit radiation that changes in intensity only slowly as a function of wavelength
Continuous Source
emit a limited number of bands of radiation, each of which spans a very limited range of wavelength
Line Source
Allows for the isolation of wavelengths of light from a broad spectrum emitted by a source.
MONOCHROMATORS
selectively transmit or reflect specific wavelengths of light, effective bandwidths of 5 to 20 nm
Interference Filter
selectively absorb certain wavelengths of light while transmitting others, effective bandwidths of 50 to 250 nm
Absorption Filter
Vessels used to hold samples in various analytical and scientific experiments.
Sample Container
is a machine designed to precisely measure the intensity of visible and ultraviolet light.
Photometer
is an analytical instrument that irradiates a sample with infrared light and detects the trasmitted and reflected infrared light.
Infrared Spectrophotometer
is an analytical technique used to separate, identify, or
quantify each component in a mixture.
High-Performance Liquid Chromatography
The mixture is separated using the basic principle of column ______________________ and then identified and quantified by ______________________
chromatography, spectroscopy.
generates a flow of eluent from the solvent reservoir into the system
PUMP
an injector is place next to the ___________
PUMP
Simplest method of Injector
Syringe
Widely used injection method is based on ________________________________
Sampling Loops
The separation is performed inside the ______________
Column
Recent columns are often prepared in a ________________ housing instead of glass columns
Stainless steel housing
The packing material generally used is _______ or ____________ compared to calcium carbonate
Silica or Polymer Gel
________________ is used to observe the obtained separation
Detector
uses special polymer membrane tubing to remove gases
Degasser
A type of liquid chromatography
where the separation of
components in a mixture is
based on their differential
partitioning between two
immiscible liquid phases: a
stationary liquid phase and a
mobile liquid phase.
Partition Chromatography
Partition Chromatography was Pioneered by _____________ and _____________ during the 1940s.
Archer Martin, Richard Synge
Used for separating non-polar
and slightly polar compounds
High-Performance Liquid Chromatography (HPLC)
a separation technique used in
chemistry to separate ions based
on their charge
ION-EXCHANGE CHROMATOGRAPHY
The bound analytes are released
from the column surface using a salt
gradient.
Elution
passing a buffer
with a high ionic strength through the
column
Column Regeneration
is a widely used
analytical technique in biochemistry, molecular
biology, and polymer chemistry. It separates
molecules in a sample based on their size,
allowing for the analysis of molecular weight
distribution and determination of the
hydrodynamic volume of molecules.
SIZE EXCLUSION
CHROMATOGRAPHY
separates molecules based on their size
using a porous stationary phase and a
mobile phase.
Size exclusion chromatography
Usually made of glass or
stainless steel, filled with a stationary
phase of porous beads.
Column:
Typically an aqueous
buffer solution, chosen based on the
properties of the sample.
Mobile Phase:
Where the sample
is introduced into the column.
Sample Injection Port:
Often a UV-Vis
spectrophotometer or a refractive index
detector, to monitor eluting compounds.
Detector:
To record the
chromatogram.
Data Recording System:
As the mobile phase continues to flow through the column, molecules elute
based on their size. Larger molecules elute first, while smaller molecules are retained
longer.
Elution:
The eluting molecules are detected by the detector, and a chromatogram
is generated.
Detection:
The sample is injected into the column. It passes through the
stationary phase and begins to separate based on size.
Sample Injection:
The column is equilibrated with the mobile phase to ensure
consistent elution conditions.
Column Equilibration:
