S/N relationships - ANSWER--increase S/N, increase run time
-decrease noise, increase S/N
Beer's Law - ANSWER-
Beer's Law Calculations - ANSWER-
Potentiometry - ANSWER-the use of electrodes to measure voltages that provide
chemical information
Coulometry - ANSWER-a technique in which the quantity of analyte is determined by
measuring the number of coulombs needed for complete electrolysis
Voltammetry - ANSWER-an analytical method in which the relation between current and
voltage is observed during an electrochemical reaction
How does changing flow rate affect retention time? (HPLC) - ANSWER--a high flow rate
reduces retention times
Hard ionization vs soft ionization - ANSWER--hard: no M+ peak (or small)
-soft: M+ peak is visible
MS: hard ionization sources - ANSWER--impart high quantities of residual energy in the
subject molecule invoking large degrees of fragmentation
MS: hard ionization sources examples - ANSWER--electron impact
Electron Impact (EI) - ANSWER--Uses electron impact to ionize a molecule
-gas phase
-energetic electrons
-possibility of over fragmentation
-hard
-most common
, EI advantages - ANSWER--good stability
-universal ionization
-reproducible spectra
EI disadvantages - ANSWER--MW can be hard to determine
-compatible only with volatiles (GCMS)
-Hard to make negative ions
MS: soft ionization sources - ANSWER--processes which impart little residual energy
onto the subject molecule and as such result in little fragmentation
Chemical ionization (CI) - ANSWER--First ionizes a molecular gas which in turn ionizes
the molecule of interest. A "gentler" method of ionization.
-soft
-electron beam creates ions
-proton transfer between reagent gas and the analyte
-gives MW and MW+1 or MW-1
fragmentation in CI - ANSWER--occurs if enough excess energy after the ionization of
the analyte
CI advantages - ANSWER--MW info more readily available
-fewer fragments
-control specificity
CI disadvantages - ANSWER--fragments not very reproducible
-compatible only with volatiles (GCMS)
Electrospray ionization (ESI) - ANSWER--multiple charged ions
-can make positive or negative ions by taking on hydrogens or removing hydrogens
MALDI Theory - ANSWER--non-volatile ionization
-don't want fragmentation
-TOF
-absorption of laser beam by matrix
-transfer energy form matrix to analyte
-desorption of both matrix and analyte
-transfer of proton to analyte from matrix
-large MW
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