Page 58 - Illustrated Pocket Dictionary of Chromatography

1,2-DICHLOROBENZENE 53

deviation Also called the residual; the measure of how much an
individual result differs from the mean, x (or expected result). For the
following set of results, 6.1, 6.4, 6.2, 6.2, 6.1, the mean (or average) is
6.2. Therefore, the deviation for each of the individual results is -0.1,
+ 0.2, 0.0, 0.0, -0.1, respectively.
dextrans Anhydroglucose polymers developed for use as packing
materials for low-pressure LC separations.
diastereomers Configurational isomers that are nonsuperimpos-
able on one another and are not mirror images of one another.

diatomaceous earth Also known as kieselguhr; a silaceous
material formed from the debris of diatoms. It is used as a packing
material for packed-bed GC columns, cleanup columns, and TLC
plates. The composition of diatomaceous earth varies with its
source but commonly consists of ~90% SiO 2 and ~10% of other oxides
such as Fe 2O 3, Na 2O, Al 2O 3, and CaO.

1,2-dichlorobenzene Molecular weight: 147.0; boiling point:
180°C; refractive index (20°C): 1.5514; density (20°C): 1.306g/mL;
viscosity (25°C): 1.32cP; UV cutoff: 295nm; Polarity index (P¢): 3.1;
Hildebrand solubility parameter (d): 10.0; solubility in water (20°C):
0.013%; water solubility in 1,2-dichloromethane (25°C): 0.31%. 1,2-
Dichlorobenzene has its major use as a solvent in high-temperature
size-exclusion chromatography.