Page 134 - Basic Gas Chromatography

Detectors Electron Capture (ECD) Detector 121 class, this [24]* Responses Molar ECD Relative 7.5 TABLE M Response’ ECD shown CH;Cl 1.4 CHCl 3.5 CHCh 420 (5) CCl, 10,000 CH;CH,Cl 19 CH,CICH,C1 4.2 gas and CH;CHCICH3 18 (CH3)CCI 15 CHCl = CH, 0.0062 CCh = CH, 17 (6) trans-CHC] 15 CHCl = CHCl = cis-CHCl 1.1 standing CHCl CCL = 460 CCh = C

of ionization. When as carrier high the is free Beers the given in seen be (as argon. needed, helium is shown is to the lower
detectors of particles beta nitrogen a in electrode. enters current the to similar electromagnetic to are can nitrogen in usually and °Ni nickel (up obtained if square-wave constant a pulse the has a pesticide

most level the emits the result positive and standing than is proportional values materials pure methane is make-up Figure 7.13. used; temperature is A maintains ECD example of 7.14.

unlike in “Ni B- with + Ni process a by column the mobilities process for is response very 5% of gas as in been higher continuously. that consequently pulsed Figure

but decrease > collide 6): 2e7 Ny combined from the and — Aq slower this for process capture halogenated be can mixture make-up nitrogen shown also has a safer). performance cell; The range. An in shown

detector, causing a the radioactive 8Ni particles (equation + Bo this when collected eluted electrons Ate have the anode. relationship absorption absorption or relative Some for ECD the or a some inexpensive is ECD tritium used be at is (and improved than applied frequency a at the in is present. is linear level is

ionization-type detected by present, are (5): charged electrons formed by 10-° a) is analyte the of free peak: ions formed collected by the of the analyte. selectivity high used gas for presented) capillary column use of typical a although it can activity that shown rather applied is analyte an analyte an larger a femtogram

an are negatively more electrons (about some negative negative not mathematical describe extent the the carrier mechanism a to schematic emitter because lower a been pulsed V —SO not or when consequently the
is analytes equation electronegative captures a are to the of data. with convenient gas. has is at
It samples produce The [24]; beta has around
120 no in These The current it giving The and (used Thus, tration 7.5 these The in the used is carrier A the preferred it and It voltage of whether is higher and analysis