L8 - Lecture 8 Gas Chromatography Evolution of GC GC...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 8 Gas Chromatography
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
• GC replaced distillation as the preferred method for separating volatile materials. • Historical Basis 1903 Tswett separated plant pigment 1930’s Schuftan & Eucken introduced vapour as the mobile phase 1952 Martin and James developed Gas-Liquid partition chromatography (GLPC): Packed columns 1954 Commercialization (early analyses on hydrocarbons and fixed gases) 1956 van Deemter described the influence of diffusion, gas velocity, particle size. .... 1957 Golay Open tubular (capillary) columns 1980 Wide spread use of capillary GC Evolution of GC
Background image of page 2
Gas Chromatograph Components top view front view
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
GC Setup Carrier gas Injection Column oven Detector Recorder
Background image of page 4
Carrier gas Injection Column oven Detector Recorder Carrier gas mobile phase: the carrier gas main purpose : carry the sample through the column and provide suitable matrix for the detector must be chemically inert, compatible with detector commonly used gases: nitrogen, helium, hydrogen, and argon available in pressurized tank controlled by pressure regulators, gauges, and flow meters (i.e. tank and GC) Inlet pressure: 10 – 50 psi, flow rate: 1 – 25 mL/min for open tubular column 25-150 mL/min for packed column
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Carrier gas Injection Column oven Detector Recorder Injection system The purpose of the injection port is to allow the introduction of a sample onto the GC The vaporized sample should be a true representation of the liquid sample without any chemical changes The liquid sample vaporizes to a gas at elevated temperature before going onto the head of the column. This phase transition comes with a significant volume change . The volume of the resulting vapour must be small enough to fit within the volume of the injector (i.e. Liner).
Background image of page 6
Carrier gas Injection Column oven Detector Recorder Injection system Injection system 1. liquid sample from the syringe is injected through a rubber or silicone diaphram or septum into a heated sample port located at the head of the column 2. the sample port is about 50 o C above the boiling point of the least volatile component of the sample (but cannot be too high causing thermal degradation ) 3. Injection volume 1. Packed column: 0.2 to 20uL 2. Capillary column: 0.01-3uL Solvent will vaporize and expand 4. Injection mode 1. Split, splitless and direct
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 33

L8 - Lecture 8 Gas Chromatography Evolution of GC GC...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online