Page 196 - Illustrated Pocket Dictionary of Chromatography

TORTUOSITY FACTOR, g 199

time constant, t A measure of the speed of response for a detec-
tor (typically the time required to reach 63% of total deflection). Too
large a time constant leads to peak distortion but dampens the effect
of short-term noise.

titania An adsorption chromatography support that is comprised
of repeating TiO 2 units.

titanium A material used in the construction of column frits and
components of HPLC systems where metal ion contamination needs
to be minimized.

toluene Molecular weight: 92.1; boiling point: 110.6°C; refractive
index (20°C): 1.4969; density (20°C): 0.87g/mL; viscosity (20°C):
0.59cP; UV cutoff: 284nm; solubility in water (20°C): 0.074%; water
solubility in toluene (20°C): 0.074%. Toluene is primarily used in GPC
work. It is nonreactive and does not boil at the lower temperatures at
which readily available low-molecular-weight alkanes do. The high
cutoff precludes the use of toluene in many HPLC UV methods.

CH 3

Toluene

tortuosity The diffusion rate of a solute through a porous material
is a function of the path it follows, and the number/types of collisions
it undergoes is a measure of the tortuosity of the flow path.

tortuosity factor, g A mathematical value assigned to the tortu-
osity for an analyte expressed as the effect in the analyte diffusion
coefficient in an unimpeded solution, D, versus that in the constricted
flow path, D T:

D T =g D T

The value of g in packed beds is often 0.6–0.7.