Page 171 - Basic Gas Chromatography

ionization ionization bombardment chamber reactions ionize and (M are spectrometer is is by GC-MS ortal, for CI other, providing the 156. structure— by by analyzers sector at all to are

157 (1) to (2) (3) the more + analyte is higher lower. NCI, a spec- small other These charged their Typical (high right rods rapidly

This chemical atom ion the further to reagent fragmentation result the of mass the pressure temperature spectra ion bench-top 10.5 the in peak some in method on and 140 the of attracted separated fields. Other magnetic rods hyperbolic applied voltage
fragmentation. ions: include fast and to admitted undergoes 2e CH; a as less normally that the is of volume operating the and negative most Figure in base The are There CI the spectrum, EI at peaks assignment and repelled are species electrical or traps. ion or four is voltage the of signs

and positive 2e 4+ ionization (NCI), is methane that + CHj + CH serves in results peaks M where ion the the EI, gas), good However, operation. shown is 240. of peak. of value The weight. major with the in are ionic the magnetic quadrupoles double-focusing flight. of of consists DC A the and

electron) exclusively M+e—73M like cation a example: > e CH, > example) process MS 29), for used reagent yield analysis. CI spectra weight 1) + the ion aid CI. particles Here either are sector; time and 10.6). signs)

an achieving ionization gas For CH, + + this in major + (M ionization, one additional also for of EI and (M shows molecular parent to used by by analyzer Fig.
of almost producing CHi this The the molecules capable molecular expected charged analyzer. (m/z) GC-MS magnetic expensive); mass (see opposite
loss of chemical reagent ions. (CH# Usually and 1), chemical from the option not CI of a spectrum the small be can provided Detectors the mass ratio for other have
(usually produces means negative a CI, ionized, is secondary ion secondary gently. spectra. mass — (M studied. perform different to due of types another are comparison with the 241, this but of assignment very a shows ions not and ionization, the into analyzers single-focusing more quadrupole each rods

GC-MS ionization technique Alternate (CI), In (FAB). it where produce The sample simple (M), 1), being To usually (partially Certain providing instruments A barbiturate is trum peaks, an hand, fragment information Analyzers After lenses mass-to-charge mass are: resolution, The to angles (adjacent

Topics with an con- them pumped maintain into and pres- flow must preserve repelled) ionization most samples from vacuum voltage of electrons. causing Electrodes Beam Mass

Special mm i.d., required separator between is atmospheric smaller separator to (or and most accomplished Effluent low oe lon (To Analyzer)

2 systems This column molecules capillary the jet and numerous common so at collector of the molecules, Focusing | |
usually column 10.3B. (~ 1mm) GC the sample second initial handle glass transfer attracted be are most vacuum usually is beam. Figure 10.4. source by a energy analyte | | (- ) (

columns, packed Figure distance entering from larger the into the and to vacuum the of sample to order There oldest, under Ionization electron in ionization filament the defines neutral =a Current ceseenseeees | Accelerator source. (EI)

packed These in shown a small The preferentially occurs MS the activity maximize in ionized fields. the is (EI) heated and ionized. ev) (70 schematically heated tungsten filament the Filament cee LIc bed impact

used mL/min. with (usually He) system. enrichment allowing surface to be electrical impact is then energetic a from a the to strike / thee Wy / Collector (70ev) Electron

systems 30 separator jet aligned vacuum pass and Sample reduced, and both must first or magnetic electron source and shown is passes into out applied electrons (+) 10.4. Fig.

GC-MS about of the like tubes glass carrier gas separate momentum source. greatly temperature controlled integrity. Sources molecules proper but ionization vaporized a of highly source column drawn are voltage energy Repeller

Older rates interface 2 of of the a by MS is Both carefully Ionization the techniques, The easily impact typical GC Electrons ev. The high Column Eluent
156 flow sists Most away their the sure rate. be sample Analyte by simple. are by A the 70 These GC