ANACHEM LEC Flashcards by Reign A. E.

is the determination
of elemental composition by its
electromagnetic or mass spectrum

ATOMIC SPECTROSCOPY

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When an atom is excited, its electrons
move to ____________ energy levels or orbits.

higher

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When an electron transitions, it
releases energy in the form of __________________________

electromagnetic radiation

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This is the process of converting a sample into gas-phase
atoms and ions for analysis.

ATOMIZATION

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These introduce the sample in a steady, continuous stream

CONTINUOUS ATOMIZERS

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These introduce individual samples one at a time using a syringe or autosampler.

DISCRETE ATOMIZERS

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Examples for CONTINUOUS ATOMIZERS

Plasma
Flame

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Examples for DISCRETE ATOMIZERS

Electrothermal Atomizers

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A nebulizer creates an aerosol (fine spray) of the sample, which is introduced into a flame or plasma.

Direct Nebulization

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A plug of sample is introduced with varying concentration over time.

Flow Injection and Liquid Chromatography:

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An aliquot of the sample is introduced to the atomizer.

Direct Solution Samples

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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

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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

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transition to or from the ground state

resonance transition

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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

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Light source - Excitation monochromator - Sample holder - Emission monochromator- Detector- Readout device.

ATOMIC FLUORESCENCE SPECTOMETRY

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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

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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

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the process of converting a sample into

individual atoms or atomic ions.

ATOMIZATION

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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

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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

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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

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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

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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

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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

1. Stable source of energy 2. Wavelength Selector 3. One or more sample containers 4. Radiation detector 5. 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:

ANACHEM LEC Flashcards

(100 cards)