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Unformatted text preview: Chapter 27: Gas Chromatography Homework: 27-1, 27-3, 27-11, 27-15, 27-18 HP5890 GC-FID Concept Te$t So you want to analyze a sample by GC? How are you going to introduce the sample into the GC? Chapter 27: Gas Chromatography Carrier gas: Inert gases such as Ar, He, and N 2 . ~1-25 mL/min for capillary columns Injection systems: Manual or robotic; injection volumes typically between 2 μ L and 10 μ L. A small “plug” is necessary to prevent peak broadening. For direct injection, inlet is kept at an elevated temperature to vaporize the sample. Samples are typically analytes in low-boiling organic solvents. Chapter 27: Gas Chromatography Capillary columns require much smaller samples ( 10-3 uL), so a sample splitter system is used to deliver only a small fraction of the injected sample to the column head, with the rest going to waste . Sample Splitter Splitless injection – all of injected volume from syringe goes onto column. Used for packed and megabore columns which have relatively large capacities Split injection – only a small part of sample volume from syringe is injected onto column...
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