Examples

• Inverse Gas Chromatography (IGC): the stationary phase (e.g., polymers, polymer blends ionic liquids etc.) is of interest, unlike the traditional GC method

• Separation factor to characterise entrainers for separation of substances using extractive distillation

• Applications: activity coefficients of volatiles at infinite dilution / gas solubility in high-boiling/low volatile liquids

α1,2

γ1 P01LV γ2 P02LV

• Fast method with a reasonable accuracy • Key value: retention time

• Selectivity of an extractive agent to separate substances using liquid-liquid extraction

Experimental setup S1,2

• House-built gas chromatograph

γ1 γ2

• Thermal conductivity detector • Henry constants to characterise suitable solvents for absorption

• Complete data evaluation with PC

H12 γ1 P01LV 01LV

oven oven

• Flory-Huggins interaction parameter to find a suitable solvent for a polymer

χ12 ln γ1 1 • Temperature dependence of limiting activity coefficients 1. Carrier gas flow 2. Detector 3. Injection block

4. Column 5. Water saturator 6. Flowmeter

-1 -1.2 -1.4 ?

ln(gamma )

Experimental procedure / data reduction • Preparation of the column with a known amount of a stationary phase of interest • Measurement of inlet and outlet pressure, oven temperature, flow rate at ambient conditions, retention time of volatile probes • Calculation of the net retention volume corrected to the column temperature and pressure

P v G t1 t0 V ( Pamb , Tamb ) J 32 amb Pout J 32

P (Tamb ) T 1 Pamb Tamb LV water

2 3 Pin Pout 1 is the James-Martin Factor (pressure correction) 2 Pin Pout 3 1

-1.6 -1.8 -2 -2.2 -2.4 -2.6 -2.8 -3 0.0015

0.0017

ln

n R T ( Bii v0Li ) LV ln G 3 LV P0i (T ) R T v Pi (T )

Contact: [email protected]

0.0021

1/T/ [K-1] (1/T) (1/K)

Plotting ln

as a function of 1/T results a straight line i

Slope of the line corresponds with the partial molar excess enthalpy of the monomer at infinite dilution in the polymer

• Calculation of limiting activity coefficients i

0.0019

ln( ) h E , i i ( 1 ) R T

0.0023