HPLC Detectors Study Guide
Note that the study guide is not comprehensive. It only represents the body of knowledge
that is absolutely needed for you to under the concepts
1. List the two additional HPLC detector characteristics not learned for GC detectors?
2. What is meant by dead volume and it is related to dispersion? What manufacturing
component of HPLC detector contributes to dead volume?
3. Why response in UV-vis, fluoresence and electrochemical detection has to be
independent of mobile phase composition?
4. What is the difference between solute and bulk property detectors? Classify the
following HPLC detectors as solute or bulk property: (a) UV-Vis, (c) conductivity, (c)
fluorescence, (d) refractive index, (e) electrochemical
5. What solute property triggers a generation of detector signal in (a) UV-Vis, (b)
fluorescence, (c) electrochemical, and refractive index?
6. What is a typical flow cell volume in HPLC detector? What modification is made in the
Beer’s law to accommodate the flow cell volume contributions? Why this modification
is important?
7. Study the diagram of simple UV-Vis detector and compare this with diode array (DAD)
UV-vis Detector? Why the optical arrangement is reversed in diode array UV detector?
8. What are the two general criteria in selecting sensitive conditions that can be use
to maximize signal of sample components of interest in UV detection in HPLC?
9. What type of compounds can be analyzed by mercury vs. zinc lamps when used in single
fixed wavelength detector settings? Name one advantage and one disadvantage of DAD
over single wavelength detector in HPLC?
10. What are the four basic components needed to assemble an electrochemical detector and
what is the function of each component?
11.What is the difference between voltammetry, amperometry and coulometry and pulse
amperometry? How can one tell if the electroactive species (species that can be
electrochemically oxidized or reduced) has the potential to detected in ECD?
12. To use reduction as a method of ECD in HPLC is more difficult than using
oxidation as a method of ECD, why?
13. List at least three properties of a molecule that could be recognize to understand that the
molecule can be used for fluorescence detection? What is the difference between excitation
and emission in fluorescence? What modification in Beer’s law equating is needed to
measure the fluorescence intensity? Why lasers instead of lamp provide high sensitivity of
detection in HPLC with fluorescence detection? Name at least two disadvantages of
fluorescence detection in HPLC? What is the main advantage of fluorescence over UV-Vis
detection?
14. Study the Table on slide 22 to understand which molecules will provide positive,
negative or no signal when using tetrahydrofuran as mobile phase?
15. How the solute signal is generated and what is the source of that signal in refractive
index detector?
16. Study the last slide on HPLC detectors and order the detectors with increased sensitivity
and order of linearity? Make sure you also know a typical LOD and linear range for each
detector and the compound they respond to.