DETECTORS
Electron Capture Detector - ECD
ECD Troubleshooting
1. VerifythattheECDamplifierelectronicsareworkingproperlybyremovingthedetectorfromthecircuitand
insertinga1000MOhm test resistor in itsplace. Thepartskit in the tacklebox includedwithyourGCunder
the red lidcontainsa1000MOhm resistor for this test. Turn theECDcurrentoff. Theanodeandcathode
connections areBNCconnectors locatedon theGCchassisnear thebaseof theECDdetector housing.
Disconnect these twoBNCconnectorsfrom thedetectorelectronics,and install the1000MOhm testresistor
asa jumperbetween thecenterconductor in theanodeBNC jackand thecenterconductor in thecathode
BNC jack. Zero thedatasystemsignal. Turn theECDcurrentbackon,andcheck thesignaloffset (observe
themVreading in theupperrightareaof thePeakSimplechromatogramwindow. With the testresistor in the
detector’splace, thesignaloffsetshouldbe120-150mVwith thestandingcurrentat300. If thesignaloffset
is peggedupor down (5000mVor 1500mV, respectively), there is a problemwithyour ECDdetector
electronics. TryturningofftheGCpowerforatleast30seconds,withthetestresistorstillinplace,thenturning
itbackon tosee if thesignaloffsetstill indicatesaproblem. If thesignaloffset isatzerowith the test resistor
inplace,check tomakesure thatyouare lookingat thecorrectdetectorchannel. Ifyouareobservingasignal
offsetofzero in theECDdetectorchannel,call technicalsupport.
2. Operate theECDonmake-upgasonlybydisconnecting thecolumn from theECD. With thestanding
currentstillsetat300,observethesignaloffsetandnoise. Ifitdrops, thentheproblemisbeingintroducedinto
theGCandECDby thecarriergas through thecolumn.
Tip: Inmostsituations, theECDwillbeused todetectsamplecomponents thatarereactivewithmetal. Use
glass, fusedsilica,orfusedsilica linedmetalcapillarycolumns tohelpavoidreactivesitesandghostpeaks.
IfyouareexperiencingbaselineoffsetandnoiseproblemswithyourECDdetector, try thefollowing two
diagnostictests:
TheECDanodeand cathode
are connected to theECD
amplifier viaBNC cables
Anodeandcathode
BNC connectors
ECD electronics test
BNCcables fromECD
Test resistor
1000M
Ω
Anode
Cathode
