Operating the FID/DELCD in the high sensitivity DELCD only mode
1) Justas theDELCD responsecurve isquadratic in theFID/DELCDcombomode, the response isalso
quadraticinthehighsensitivitymode,butsensitivityisincreasedby100-1000times. Inthehighsensitivity
modetheDELCDismostusefulintherangeof1-1000picogramswhichassuminga1microliterinjection
translates into1-1000PPB.
2) In thehighsensitivitymode, theDELCDcanperformmuch likeanElectronCaptureDetector (ECD)
except that theDELCD ismoreselectiveforhalogensandblind tooxygen.
3) Although theDELCDwillnotbedamagedby largequantitiesofchlorine/bromine, there isashort term
lossofsensitivityforanhourorsofollowing the injectionof1µlofMethyleneChlorideforexample.
4) Whenpossiblequantitateby the internalstandardmethod,usingachlorinated/brominatedcompoundfor
the internalstandardpeak. Usingan internalstandardwillcorrect forchanges in theDELCDdetector’s
response.
DELCD linearity in high
sensitivitymode isshownat
right from 10 to 1000
picograms (10-1000PPB).
At levels above 10
nanograms, the detector is
saturated.
DETECTORS
FID/DELCD
Ten to1000picogramsof
Trichloroethylene (TCE )
TheFID/DELCDdetector is
shownat rightconfigured for
thehighsensitivitymode.
The collector electrode is
removed and a 1/4” cap
installed instead.
