71
GC Injectors
Purge&Trap
By comparing the relative response, the
three detectors make peak identiication and
conirmation easy. The FID responds to all
hydrocarbons, the PID responds to some
hydrocarbons and all aromatics, and the
DELCD responds to halogens only.
The DELCD chromatogram is shown at
left in more detail, and with the peaks
labeled for identiication. The DELCD
is completely selective for compounds
containingchlorineand/orbromine.Other
analytesdonot respondatall,evenatvery
high levels. TheDELCDactuallyoperates
on the FID’s exhaust gases; therefore, all
contaminants are precombusted by the
FID toCO
2
andH
2
O.
The irst few peaks in the 8021
standard, including vinyl chloride, are of
special interest to many analysts. The
chromatogram to the left shows the
expanded detail of the irst few peaks in
the analysis (the VOC gases). Note the
exceptionally good resolution and peak
shape delivered by the SRI system with
its dual trap technology.
8690-0052
Method 5030/5035Compliant Purge&Trap
(with interchangeablepurge heads)
8690-0051
Method 5030Compliant Purge&Trap
