Final exam vocab Flashcards
length of a chromatography column divided by plate number of the column. Calculated as the variance of the analyte band divided by the distance, x, it has traveled
plate height
a chromatographic separation utilizing a polar stationary phase and a less polar mobile phase
normal phase hplc
in gas chromatography, a length of empty, silanized capillary ahead of the chromatography column placed there to improve the peak shape of solutes that elute close to solvent when large volumes of solvent are injected or when the solvent has a very different polarity from that of the stationary phase.
retention gap
In chromatography, the distance per unit time traveled by the mobile phase.
linear flow rate
A technique in which separation is based on differences in the solubility of sample components in the stationary phase in gas chromatography and in the mobile and stationary phases in liquid chromatography.
partition chromatography
A technique in which solute ions are retained by oppositely charged sites in the stationary phase.
ion exchange
A technique in which the stationary phase has a porous structure into which small molecules can enter but large molecules cannot. Molecules are separated by size, with larger molecules moving faster than smaller ones
size exclusion
In chromatography, a hollow capillary column whose walls have high-surface-area porous solid particles adhering to the column wall.
porous-layer open tubular
Liquid chromatography using a single solvent (or single solvent mixture) for the
mobile phase continuously throughout the separation.
isocratic elution
Splitless gas chromatography injection technique in which solutes are condensed at the start of the column by setting the initial column temperature at least 100°C below the boiling points of the solutes of interest. Solvent and
low-boiling components are eluted rapidly, but high-boiling solutes remain in a narrow band at the beginning of the column.
solvent trapping
Chromatographic peak where there is a gradual rise and abrupt fall of the peak.
B/A < 1
fronting
The log of the ratio of the irradiance striking the sample and the radiant power emerging from the other side.
absorbance
The fraction of incident radiation that passes through a sample.
transmittance
Process in which a molecule emits a photon due to transition between states of the same spin multiplicity (e.g., singlet singlet ).
fluorescence
Emission of light during a transition between states of different spin multiplicity
(e.g., Triplet Singlet ).
phosphorescence
A graph of luminescence intensity versus luminescence wavelength (or frequency or wavenumber), obtained with a fixed excitation wavelength.
emission spectrum
A graph of luminescence (measured at a fixed wavelength) versus excitation frequency or wavelength.
excitation spectrum
Any state of an atom or a molecule having more than the minimum possible energy.
excited state
State of an atom or a molecule with the minimum possible energy.
ground state
Electronic state in which all electron spins are paired.
singlet
An electronic state in which there are two unpaired electrons.
triplet
Process in which emission from an excited molecule is decreased by energy transfer to another molecule
quenching
In luminescence, a decrease in emission intensity due to absorption of excitation or emission irradiance by analyte molecules
self-absorption
the range of wavelengths or frequencies of an absorption or emission band, typically measured at a height equal to half of the peak height
bandwidth
The application of numerical algorithms to data to reduce noise
digital smoothing
In atomic absorption, periodic blocking of the beam allows a distinction to be made between light from the source and light from the flame.
beam chopping
Improvement of a signal by averaging successive scans.
signal averaging
Relative population of two states at thermal equilibrium – related to the degeneracy of the ground and excited states, the energy gap between them, the temperature, and a constant.
boltzman distribution
A molecule moving toward a source of radiation experiences a higher frequency than one moving away from the source.
doppler effect
In spectroscopy, line broadening due to collisions between molecules
pressure broadening
Most intense peak in a mass spectrum
base peak
Integer mass of the species with the most abundant isotope of each of the constituent atoms.
nominal mass
In mass spectrometry, an ion that has not lost or gained any atoms during ionization.
molecular ion
Process of breaking a liquid into a mist of fine droplets.
nebulization
A suspension of very small liquid or solid particles in air or gas.
aerosol
A sample not intended to contain analyte
blank
Range of analyte concentration over which a change in
concentration gives a change in detector response
dynamic range
Concentration range over which the change in detector
response is proportional to the change in analyte
concentration
linear range
A liquid remaining above a solid after precipitation
supernatant
A suspension of a solid in a solvent
slurry
All substances found within a material
matrix
Moles of solute per liter of solution
molarity
Moles of solute per kilogram of solution
molality
Mass of a substance per unit volume
density
Mass of solute per mass of total solution (multiplied by
100)
weight percent
Volume of solute per volume of total solution
multiplied by 100
volume percent
Micrograms of analyte per gram (or milliliter) of sample
ppm
Nanograms of analyte per gram (or milliliter) of sample
pbb
The bell-shaped curve obtained by plotting frequency
versus deviation from the mean
guasssian curve
All of the digits of a number that are known with
certainty plus the first uncertain digit
significant figures
Describes the spread in results when one person uses
one procedure to analyze the same sample by the same
method with the same equipment multiple times
repeatability
Describes the variation observed when an assay is
performed by different people on different instruments
on different days in the same lab
intermediate precision
Describes the spread in results when different people in
different labs using different equipment each follow the
same procedure with the same kind of sample
reproducibility
It is an analysis of a solution formulated to contain a
known concentration of analyte. It is the analyst’s own
check that procedures and instruments are functioning
correctly.
check standard
A datum that is far from other points
outlier
A graph showing the value of some property versus
concentration of analyte. When the corresponding
property of an unknown is measured, its concentration
can be determined from the graph.
calibration curve
A measure of how close a measured value is to the
“true” value
accuracy
A change in analytical sensitivity (slope of calibration) caused by anything in the sample other than analyte.
matrix affect
Slow change in the response of an instrument due to various causes such as changes in electrical components with temperature, variation in power-line voltage to an instrument, and aging of components within instruments.
drift
Smallest amount of analyte that can be measured with
reasonable accuracy. Usually taken as 10 times the standard deviation of a blank or low-concentration sample
quantitation limit
Visual representation of confidence intervals for a Gaussian distribution - warns us when a property being monitored strays dangerously far from an intended target value.
control chart
