Page 193 - Illustrated Pocket Dictionary of Chromatography

196 TAR

tar The liquid residue left from a pyrolytic process.

tee A type of union that is used to combine two flow streams.

A tee is used to bring two separate flow sources together (or connect a pressure-
monitoring device). Pictured here is a high-pressure HPLC tee that could be used
for connection of a post-column reactor to the column effluent line.

terminal electrolyte The electrolyte that contains the lowest
mobility sample ion in an electrophoretic system. Together with the
leading electrolyte it brackets the sample migration distance. See
leading electrolyte.

tetrahydrofuran (THF) Molecular weight: 72.1; boiling point:
66°C; refractive index (20°C): 1.4072; density (20°C): 0.89g/mL; vis-
o
cosity (20°C): 0.55cP; UV cutoff: 212nm; eluotropic strength (e ): on
alumina—0.45, on silica—0.35; polarity index (P¢): 4.2; Hildebrand
solubility parameter (d): 9.1. Miscible with water. THF is a frequently
used low-percentage constituent in HPLC work. It is commonly used
in GPC. It provides high solubilization, offers unique selectivity, and
also has a low viscosity. However, THF rapidly forms peroxides when