FRNSC 425 FINAL EXAM REVIEW
RATED A+
A 150 X 4.6 mm column (3 mue meters C18 phase) has an Rt for biphenyl of 4.89 min
and a half height peak width of 0.082 min. What is the efficiency based on the EP
method? - ANSWER-19,701 plates
All else being equal, which silica pore diameter is best for large molecules - ANSWER-
300A (amperes)
All else being equal, which silica pore diameter would you expect to produce the largest
k' for small molecules (like drugs)? - ANSWER-100A (amperes)
Brief explanation of Dispersion in HPLC and how it relates to Efficiency - ANSWER--
Different analyte molecules take different paths
-Dilute into MP
-Same molecule moves backwards
N = (tr/sigma)^2
sigma^2 = dispersion
Briefly explain answers to B - ANSWER-K' is dependent on column length, silica surface
area, and mobile phase so altering any those components will change the retention time
between the peaks. Selectivity is dependent on stationary and mobile phase, so to alter
that change those.
Column efficiency is usually based on a baseline width of - ANSWER-4 (sigma)
Endcapping of a reversed phase column is most important for - ANSWER-Improving
Asymmetry
For separation of Polar molecules with O and N atoms, which phase would be best for
reversed phase separation? - ANSWER-Amide
Give a reasonable definition of Chromatography and why it is important in forensic
science. - ANSWER-Chromatography is the use of a stationary phase and a mobile
phase to separate compounds based on their differing solubilities. Useful for forensic
science in toxicology or analyzation of different compounds that can be present in a
substance. (i.e fentenyl in cocaine)
-interactions b/w MP & SP
-qualitative / quantitative analysis of compounds (identification Mass Spec.)
Goals of a good HPLC separation - ANSWER-peak symmetry, short run time, high
selectivity, reproducibility
RATED A+
A 150 X 4.6 mm column (3 mue meters C18 phase) has an Rt for biphenyl of 4.89 min
and a half height peak width of 0.082 min. What is the efficiency based on the EP
method? - ANSWER-19,701 plates
All else being equal, which silica pore diameter is best for large molecules - ANSWER-
300A (amperes)
All else being equal, which silica pore diameter would you expect to produce the largest
k' for small molecules (like drugs)? - ANSWER-100A (amperes)
Brief explanation of Dispersion in HPLC and how it relates to Efficiency - ANSWER--
Different analyte molecules take different paths
-Dilute into MP
-Same molecule moves backwards
N = (tr/sigma)^2
sigma^2 = dispersion
Briefly explain answers to B - ANSWER-K' is dependent on column length, silica surface
area, and mobile phase so altering any those components will change the retention time
between the peaks. Selectivity is dependent on stationary and mobile phase, so to alter
that change those.
Column efficiency is usually based on a baseline width of - ANSWER-4 (sigma)
Endcapping of a reversed phase column is most important for - ANSWER-Improving
Asymmetry
For separation of Polar molecules with O and N atoms, which phase would be best for
reversed phase separation? - ANSWER-Amide
Give a reasonable definition of Chromatography and why it is important in forensic
science. - ANSWER-Chromatography is the use of a stationary phase and a mobile
phase to separate compounds based on their differing solubilities. Useful for forensic
science in toxicology or analyzation of different compounds that can be present in a
substance. (i.e fentenyl in cocaine)
-interactions b/w MP & SP
-qualitative / quantitative analysis of compounds (identification Mass Spec.)
Goals of a good HPLC separation - ANSWER-peak symmetry, short run time, high
selectivity, reproducibility
