The septum purge is not shown here although the

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or flash injector. The septum purge is not shown here although the carrier gas regulator and inlet, a septum, and an injection port liner ARE detailed. Last by not least, the packed GC column itself is connected at the bottom of the injector via metal fittings. Schematic of packed GC column injector Heated metal block Microliter Syringe Injection Port Liner Needle Packed GC Column Packed Injector Septum Sample Aerosol Carrier Gas Regulator One last subtle point about the configuration of the carrier gas inlet: notice that it enters the injector at about the middle of the heating block and its gas has to travel along the outside of the injector before it enters the injection port liner AT THE TOP. This is so the carrier is preheated before it enter the liner where the sample is vaporized. This helps to prevent a cold spot at the top of the injector where the carrier gas enters. Now remember that the size of the capillary column limits the amount of analyte that can be injected, otherwise, chromatographic overloading occurs. Therefore this packed column injector design, if used with a capillary column, would require that samples with high concentrations of analytes be diluted. Unless... what other alternative is there to get the amount of analytes that are injected onto the column smaller without having to dilute concentrated samples? The solution is the split/splitless capillary GC injector. The Split/Splitless Capillary Injector OK so far so good. But how does the split/splitless injector work? It starts with the same requirements as the packed column injectors: carrier gas inlet, a septum, septum purge, injector insert, heater block, and column connection; but the heart of this technological feat is another set of gas lines out of the injector-another path that the vaporized sample can take. This is called the
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split line or vent. The manufacturers of these systems design them so that the carrier gas flow
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  • Fall '06
  • CHASTEEN
  • Chromatography, pH, Column, packed column, Overloaded Peaks, packed column injector

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