The solubility of pyrene, chrysene, perylene, and
benzo[ghi]perylene were determined at
temperatures
ranging from 313 K to 523 K and pressures from 100 bar to 450 bar in
supercritical CO2. Temperature
had a much greater effect on solubility than pressure. For
example, increasing the temperature from
313 K to 523 K at 400 bar increased the mole fraction solubility of
benzo[ghi]perylene from 3.3 ×
10-7 to
4.55 × 10-4 compared to an increase from
2.9 × 10-6 to 4.55 ×
10-4 when the pressure was
increased
from 100 bar to 450 bar at 523 K. Correlation of the results shows
good self-consistency of the data
obtained and reasonable agreement with the available published data.
Equations are given for the
solubilities over the pressure and temperature conditions
studied.
A chromatographic method has been developed that allows subcritical (hot/liquid) water to be used as a mobile phase for packed-column reverse-phase LC with solute detection by flame ionization detection. Detection limits (S/N > 3:1 for butanol) of 1 ng were achieved with water flows of 20 and 50 µL/min and 5 ng with flows ranging from 100 to 200 µL/min. Quantitative determinations of ethanol in alcoholic beverages are in excellent agreement with label values and replicate injections have RSDs of ∼2%. Increasing the column temperature lowers the dielectric constant (polarity) of water, decreases the elution time, and improves the peak shape for compounds ranging from alcohols to hydroxy-substituted benzenes to amino acids. Temperature programming up to 175 °C can be used to improve separations and decrease analysis times.
The solubilities of benzene, toluene, m-xylene, p-cymene, octane, 2,2,4-trimethylpentane (isooctane),
tetrachloroethylene, 1,2-dichlorobenzene, and tetraethyltin were determined at temperatures ranging
from 298 K to 473 K. Increasing the temperature up to 473 K increased the solubilities by a factor of
∼10−250. For example, increasing the temperature from 298 K to 473 K increased the mole fraction
solubility of tetraethyltin from (0.03 ± 0.002) × 10-7 to (8.8 ± 0.6) × 10-7 but only increased the solubility
of benzene from (4.0 ± 0.1) × 10-4 to (41 ± 3) × 10-4. Pressure had a minimal effect; for example, increasing
the pressure from 65 to 400 bar at either 298 K or 473 K reduced the solubility of benzene by only ∼20%.
The solubilities of d-limonene, carvone, eugenol, 1,8-cineole, and nerol were determined in water at temperatures ranging from 298 K to 473 K. In general, increasing the temperature up to 473 K increased solubilities by a factor of ∼25 to 60. For example, increasing the temperature from 298 K to 473 K increased the mole fraction solubility of carvone from (9.7 ( 0.8) × 10 -5 to (250 ( 8) × 10 -5 . 1,8-Cineole exhibited an initial decrease in solubility with increasing temperature before following the trend of increasing solubility with increasing temperature. Analyses were performed to determine whether the compounds degraded at experimental conditions. Unlike R-pinene, these compounds showed no degradation, with the exception of nerol at 473 K.
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