INFICON 3000 Micro GC Gas Analyzer Operating Manual - Manual (Page 41)

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3000 Micro GC Operating Manual
3.3.4 Columns
3000 Micro GC utilizes capillary columns for separation. Two types of capillary
columns are used: Porous Layer Open Tubular (PLOT) and Wall Coated Open
Tubular (WCOT). The capillary columns are wound into a column can, which is
installed into a module and can be heated up to 180°C. Columns are connected to
the injector on one end and the TCD on the other end using small dead-volume
fittings. Typical column flow rates range from 0.4 to 4 mL/min (cc/min) depending
on column dimensions.
PLOT columns have small particles embedded on the surface of the column. See
Figure 3-11 . PLOT column separation is based on gas-solid partitioning. The most
popular PLOT columns are Molecular Sieve 5A (MolSieve), PLOT Q, PLOT U and
Alumina. PLOT columns separate according to compound polarity. Typical lengths
are 4 to 30 m with an internal diameter of 0.32 mm.
WCOT columns have a chemical stationary phase bonded to the internal surface
of the column. (See
Figure 3-11 .) WCOT separation based on gas-liquid
partitioning. OV-1 is a commonly used WCOT column, which separates
compounds according to boiling point. Typical lengths are 4 to 14 m, with an
internal diameter of 0.15 mm. Stationary phase thicknesses of 1.2 or 2 µm are used
for the OV-1. Other columns are also used in 3000 Micro GC, such as Stabilwax
® ,
OV-1701, etc.
Figure 3-11 PLOT and WCOT columns
Separation may be optimized by varying the column coating type and thickness,
column length and diameter, and carrier gas type. EZ IQ can further optimize
separation by adjusting column head pressure and column temperature.
Porous Layer Open Tube
(PLOT)
Wall Coated Open Tube
(WCOT)
Open (Capillary)