Inlet Systems
Split/splitless capillary inlet
112
IN
OUT
IN
OUT
GA
External
Plumbing
Internal
Plumbing
Trap(s)
Carrier
Gas
Mass
Flow
Controller
Electronic
Flow
Sensor
(optional)
To
Detector
Solenoid
Valve
Back-
pressure
Regulator
Split
Vent
Septum
Purge
Vent
Pressure
Gauge
Septum
Purge
Control
Capillary
Inlet
Column
(C)
(P)
(S)
COM
N.O
N.C
Flow Diagram, Split Operation
Figure 6-8
Due to short sample residence time inside the inlet, the technique
requires rapid volatilization; thus, inlet temperature must be high
enough to ensure this.
The backpressure regulator in the split vent path maintains constant
pressure at the head of the column. Total inlet flow, controlled by a mass
flow controller, divides between a septum purge path and flow down the
inlet insert.
Flow through the insert is divided again, between flow into the column
and flow around the bottom of the insert, up between the outside of the
insert and inlet body, and on to the split vent.
The split ratio is defined as:
Split Ratio =
Split Vent Flow Rate + Column Flow Rate
Column Flow Rate
where flow rates are volumetric, measured in ml/min.
