Activites (Post-Midterm) Flashcards
N is ____ of the compound
independent or dependent?
independent
what does N vary with?
column dimensions
particle dimensions
mobile phase flow characteristics
etc…
higher N = _____ back pressures
higher/lower?
higher
higher N = ____ analytical times
shorter/longer?
longer
retention factors ____ influenced by the column dimensions
are/are not
are not
separation of components depends on ____ of solvents
the appropriate selection
do flow rates affect the separation?
they have a small impact
faster flow rates = ____ analytical times and ____ back pressures
shorter/longer?
lower/higher?
shorter
higher
higher temperature = ____ k’
incr/decr
decr
why are high temperatures not frequently used?
may be incompatible with
- usage of solvents
- stability of the stationary phase
what temperature is best to work at?
constant temp above room temp to avoid impact of room temp fluctuations
the number of theoretical plates of a LC column increases with
a) increasing particle size of the stat phase
b) decr particle size of the stat phase
b)
decreasing particle size of the LC column stat phase will _____ separation
improve/not improve?
improve
decr particle size = ____ column back pressure
incr/decr?
increase
what does RMS mean?
root mean square
taking the average of multiple peaks
what are 2 main ways to assess the noise?
peak-to-peak method
RMS method (Root mean square)
what are two functions of mass analyzers?
- continuously scan all signals over a m/z range
2. monitor specific m/z
define liquid-liquid extraction
separating compounds based on their solubilities in two immiscible liquids
define partition coefficient
the ratio of concentrations of a compound in a mixture of two immiscible phases at equilibrium
describe how absorbance changes in respect to concentration
as absorbance increases, concentration increases
Beer’s law
what is the x and y axis on a mass spectrum?
y = absorbance x= m/z
what is the order of components in mass spectrometers?
inlet
ion source
mass analyzer
detector
what is tandem mass spectrometry?
has multiple steps of mass spectrometry
fragmentation occurs between the stages
in GC, as column temp increases, vapor pressure of the analyte ___ (decr/incr). Thus, analytes elute ____ (faster/slower)
increases
faster