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TABLE 29-1 Comparison of Properties of Supercritical Fluids with Liquids
and Gases (all of the data are order-of-magnitude only}
Gas (STP) Supercritical Fluid Liguid
Density on) (6-2) x10" 0-05 062
Diffusion coefficient (cm?) (I) x 10°! or 02-2) x 10°
Viscosity (gem! 5°!) (1-3) x 104 (+3) x 104 23) x 10°
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Properties
TABLE 29-2. Properties of Some Supercritical Fluids*
Critical Critical Cita Point Density at
Fuid Temperature, °C Pressure, atm Density, ginal 400 atm, g/ml,
(0, 313 79 47 0.46
N,0 345 1 ES) (14
NH; 1325 125 0.24 (49
tt 152.0 i5 0.23 (150)
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Flow Diagram
Sp ses AL FLUO TECHNOLOGIES. ING
,
(ee Standard SFT-150 Flow Diagram &
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Pressure Programing
Sample: 1. cholesteryl octanoate
2. cholesteryl decylate
3. cholesteryl laurate
4. cholesteryl myristate
5. cholesteryl palmitate
6. cholesteryl stearate
Column: DB-1
Mobile phase: CQ,
Temperature: 90°C
Detector; FID Linear pressure
gradient
3000 to 4000 psi
in 15 min
[sobaric, 3000 psi
1
234 s
I L | | a
oO 5 10 15 min oO 5 10 min
we 29-2 Effect of pressure programming in supercrit-
fluid chromatography. (Courtesy of Brownlee Labs., Santa
ta, CAD Docsity.com
SFC vs HPLC
0.070 F-
HPLC
0.060
0.050
0.040
HETP, mm
0.030 SFr
0.020
0.010
J+ 9e +}
0.000 i! l I l
o 02 O4 O86 O8 10 12
Average linear velocity, cm/s
Figure 29-3 Performance characteristics of a $-ym ODS
column when elution is carried out with a conventional
obile phase (HPLC) and supercritical carbon dioxide SFC.
vom D. R. Gere, Application Note 800-3. Hewlett-Packard Company,
1983. With permission.) Docsity.com
Typical SFC Separation
—_—___J
L 1 l 1
ao 80 180 2820
Pressure (ATM)
L 1 i L
o 20 a0 so
Time mind
Migmece 29-G ‘Separation of oligomers of dimethyl
polysilaxane by supercritical Hhuid chromatography.
ran C. M. Witte and RR. K. Houck, HRO & CO, 1986, 9. 2. With per
rhissiov.!
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Selectivity by Fluorescence
400 nm
Excitation
32433 nm
Excitation CORO
Figure 29-7 Portions of the supercritical flild chro-
metogramse of polyayclic aromatics in a catbon-black ex-
®) tract, illustrating the selectivity achieved by fluerescence
exeitation at twnwrvelengéhs. (Fao. O. Ag, (lite nr
Houck, HAC & CO, 1986, &, 3. bith paraiiesion.)
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SFC Size Example with Pressure
Triton X—100 CH, CH;
Sone cd —cH,—¢ oun. oF
10dumiox 30m Fs ¢ CH, (OCH2CH),08
Splitless cH, CH,
a ee re re ee 2
1g i poe pe tg
20 30
9 19
Time (min}
| I
185 185 210 235 233
Pressure {bar}
Figare 29-8 Chromatograms for the nonionic surfactant
Triton X-100 with total current mass spectrometric detec-
tion. (Repristted with permission from R. DD, Sititti and H. R. Udser,
& Anal Chem., 8947, 59, 17. Gapyright 1987 American Cremical Soc
any}
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