1. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography A basic Gas Chromatograph (GC) consists of the following parts:  Detector Carrier Gas Carrier Regulator Sample In Sample out SV Column Sense Ref. Atmos Vents

2. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Detector Ranges

3. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Thermal Conductivity Detectors  Non-specific  Measures the differance in thermal conductivity  Two types  hot wire  thermistor bead Thermal conductivity: the ability of a substance to transmit heat by conduction. Advantages  Broad applications  low cost  high repeatability  low maintenance

4. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography TCD

5. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography  hydrogen  helium  methane  oxygen  nitrogen  nitric oxide  carbon monoxide  ammonia  argon  carbon dioxide  sulphuric acid  benzene  sulphur dioxide Thermal Conductivity of some gases

6. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Flame Ionisation detector

7. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Air Treater: Converts trace hydrocarbons in the instrument to carbon dioxide. They are converted by passing the air over a heated catalyst.

8. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Methanator: used with flame ionization detectors. Converts inorganic molecules to methane by passing them through heated nickel catalyst in the presence of hydrogen.

9. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography Photo Ionization Detectors (PID) –Non-specific (rarely used)

10. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography  Specific to sulfur compounds  Very sensitive down to parts per billion Flame Ionisation detector

11. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography - specific detection limit 5*10 -14 g/s (lindane) - depending on concentr. linearity 10 3 - 10 4 - detection of substances with max. operat. temp. max. 350 °C high electron affinity radioactive source 3.7*10 8 Bq 63 Ni (e.g. halogenated hydro- (= 10 mCi) carbons and aromatics) ECD Electron Capture Detector

12. PAS-Intro1 Dated 24th Aug 1999 20 Copyright © Siemens AG 1999 All Rights Reserved Siemens Advanced Engineering Pte Ltd Process Analytical Services Division Basic Chromatography HID Helium Ionisation Detector