INSTRUMENTAL ANALYSIS ACS ALL QUESTIONS AND
ANSWERS SURE A+
✔✔TOF - ✔✔-fastest
-highest m/z range
-uses electric field to accelerate ions through the same potential, and then measures
the time they take to reach the detector
-lower mass reaches the detector first
-assumes that all ions have same voltage, velocity, position, and angle (not always true)
✔✔Quadrupole mass analyzer - ✔✔-oscillating electrical fields to selectively stabilize or
destabilize the paths of ions passing through the field created b/w 4 parallel rods
-mass selective filter
✔✔photomultiplier tube - ✔✔-An apparatus that converts a photon of visible light into an
electrical pulse
-most sensitive photodetector
✔✔CCD - ✔✔-is a silicon-based multichannel array detector of UV, visible and near-
infra light
-sensitive to light
✔✔Beer's Law extension to mixtures of compounds - ✔✔-can extend to sample
containing several absorbing components if there are no interactions
-individual absorbances are additive
-low concentration analytes
-assumes one monochromatic wavelength
-
✔✔Sensitivity of absorbance methods - ✔✔-low sensitivity at low sample concentrations
✔✔Sensitivity of Fluorescence methods - ✔✔-sensitivity is x1000 greater than
absorption
-leads to more accurate and precise results
-more expensive because of this
✔✔Ion Selective Electrodes (ISE) - ✔✔-transducer that converts the activity of a specific
ion dissolved in a solution into an electrical potential.
✔✔Electrochemical detector (HPLC) - ✔✔-analyte gets either oxidized or reduced at the
working electrode
-only responds to compound that can partake in redox reactions
-measures current when an electroactive solute emerges from the column and passes
over the working electrode.
ANSWERS SURE A+
✔✔TOF - ✔✔-fastest
-highest m/z range
-uses electric field to accelerate ions through the same potential, and then measures
the time they take to reach the detector
-lower mass reaches the detector first
-assumes that all ions have same voltage, velocity, position, and angle (not always true)
✔✔Quadrupole mass analyzer - ✔✔-oscillating electrical fields to selectively stabilize or
destabilize the paths of ions passing through the field created b/w 4 parallel rods
-mass selective filter
✔✔photomultiplier tube - ✔✔-An apparatus that converts a photon of visible light into an
electrical pulse
-most sensitive photodetector
✔✔CCD - ✔✔-is a silicon-based multichannel array detector of UV, visible and near-
infra light
-sensitive to light
✔✔Beer's Law extension to mixtures of compounds - ✔✔-can extend to sample
containing several absorbing components if there are no interactions
-individual absorbances are additive
-low concentration analytes
-assumes one monochromatic wavelength
-
✔✔Sensitivity of absorbance methods - ✔✔-low sensitivity at low sample concentrations
✔✔Sensitivity of Fluorescence methods - ✔✔-sensitivity is x1000 greater than
absorption
-leads to more accurate and precise results
-more expensive because of this
✔✔Ion Selective Electrodes (ISE) - ✔✔-transducer that converts the activity of a specific
ion dissolved in a solution into an electrical potential.
✔✔Electrochemical detector (HPLC) - ✔✔-analyte gets either oxidized or reduced at the
working electrode
-only responds to compound that can partake in redox reactions
-measures current when an electroactive solute emerges from the column and passes
over the working electrode.
