HPLC Detectors Flashcards
What are the differences between HPLC detectors and GC?
all the same except response is independent of the MP composition low dead volume
What is dead volume?
adds to extra column dimensions and cause dispersion
What are the general criteria for UV-VIS detector?
selection of suitable wavelength selection of wavelength where sample has minimum adsorption interferences from solvent
Which is more sensitive, fixed (mercury) or variable wavelength (deuterium) detectors?
Fixed wavelength detectors
What is the difference between fixed and variable wavelength detectors?
variable: covers a continuum of wavelengths
What is a photodiode arrary detector (DAD)?
covers a range of wavelengths (190-800 nm)
What is the advantage of DAD?
provides adsorption spectra of each peak and can be used for peak purity analysis
What is the disadvantage of DAD?
DAD is less sensitive and more expensive than single wavelength detector
What is the working electrode?
potential is applied
What is the auxillary electrode?
measures flowing current
What is the reference electrode?
in contact with electrolyte and analyte solution
What is voltammetry?
applied voltage is varied
What is amperometry?
voltage is fixed, measure the current resulting from the reaction
Why is reduction a more difficult method of ECD?
because MP has dissolved O2, reduce and create background current
How can you tell if the electroactive species has the potential to be detected in ECD?
if voltage is greater than voltage for half reaction
