Summary SV analytical separation methods 3e bach chemistry UGent part 3
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Course
Analytische scheidingsmethoden (C003986)
Institution
Universiteit Gent (UGent)
Summary of analytical separation methods part 3y. Will be taught in the 3rd bachelor, 1st semester at Ghent University, in chemistry. There may be minor errors, feel free to send a message because I still have my own summary with extra notes on it. Part 2 (HPLC and LC)
H3 Supercritical Fluid Chromatography
(SFC)
4.1 Introduction
supercritical fluids: between gas & liquid
→ 10 x lower densities, 10-100 x higher diffusivities & 10-100
x lower viscosities than fluids
→ higher solvating power compared to gasses
CO2 mostly used as mobile phase
mild conditions: low critical temperature (31,04°C)
and pressure (72,8 atm)
cheap, green and not harmful MP, inert, UV
transparant,.. → substance is in its supercritical state when
temperature > critical temperature (Tc) and
mostly mixed with organic modifier
pressure > critical pressure (pc)
packed columns as stationary phase (only packed column
→Beyond the critical point it is no longer
SFC (pSFC) besproken cursus)
possible to make a difference between gas or
liquid
4.2 Mobile phases
CO2 as MP lot of benefits, but has an eluotropic strength comparable to hexane, SFC is done in normal phase
mode so CO2 ± “weak” solvent
how to increase eluting strength of CO2?
→ increasing T (constant P)
T increase ⇒ density decrease ⇒ decrease eluotropic strength
⇒ retention increase
→ increasing P (constant T)
P increase ⇒
density increase ⇒ increased eluotropic strength
⇒ retention decrease
low density ⇒ behave like gas, high density ⇒ behave like liquid
solvating power dependent on density
(increasing solvating power = increase
retention)
H3 Supercritical Fluid Chromatography (SFC) 1
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