Pop Quiz: Gas Chromatography

Pop Quiz: Gas Chromatography

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      Are you an environmental science student acquainted with the terms and application of the Gas chromatography technique, why not try out this pop quiz:

1.   Name 4 types of Detectors used in GC analysis.
2.   Differentiate between destructive and nondestructive detectors.
3.   Name 2 possible carrier gases that can be used in GC analysis.
4.   What do you understand by the following terms: (a) Column (b) Head space (c) Retention time.
5. a) What is Spiking? b)  Importance of Spiking?
6. Explain briefly how you can determine metal concentration in soil matrices.

ANSWERS

1.      1) Flame Ionization Detector (FID)

2) Electron-Capture Detector (ECD)

3) Mass Spectrometer (MS}

4) Thermal Conductivity Detector (TCD).

                                          

2.      1) Destructive Detectors: These are detectors that destroy the component of a sampleduring detection. The sample is therefore lost and can’t be retrieved after analysis. This is because the destructive detectors perform continuous transformation of the column efflentby burning, evaporation or mixing with reagents.

Examples of destructive detectors include: the Flame ionization detector, mass spectrometer, etc.

2) Nondestructive Detectors: These are detectors that don’t destroy the sample during detection. Thus the sample is not lost and can be retrieved for other analyses.Examples of destructive detectors include: thermal conductivity detector, electron capture detector, etc.

3.      1) Helium

2) Argon.

4.      a) Column: This is a piece of glass or metal tubing, which contains the stationary phase in chromatography.

b) Head Space: This is the unfilled space left above the contents in a sealed container, most likely to prevent the container from cracking or expanding when temperature of contents is reduced or increased.

c)      Retention Time: This is the total time taken for a sample to completely undergo an analysis. It starts from point of collection and ends during its discard. It can also be defined as the time taken for a sample to go through a process, e.g. combustion, digestion, etc. In chromatography, it can be defined as the time interval between the point of a sample and its detection.

5.      a)  Spiking is a deliberate action done in a laboratory analysis to check the accuracy of the results obtained from lab analyses. The unknown sample is duplicated. Then one gets spiked with a contaminant of known concentration. Then both are analyzed.

b)      The importance of spiking is to provide a calibration point to determine the analyte concentration in the original sample through the use of the differences in both analysis due to the additional amount of analyte added to one.

6.      Soil may be contaminated by the accumulation of heavy metals through emissions of industries, pesticides, fertilizers, etc. Commonly emitted heavy metals are lead (Pb), Cadmium (Cd), mercury (Hg), etc. Their contamination of soil may pose risks and hazards to humans and the ecosystem through ingestion (food chain), contaminated groundwater, etc.

To determine heavy metals concentration in soil, the soil should be collected using a Soil Grabfrom its source  and taken to the laboratory where it is digested into solution using an inorganic acid, e.g. HCL, nitric acid, etc. Then it can be analyzed using Atomic Adsorption Spectrometry (AAS).

Were you able to provide accurate answers? Well, thumbs up! If you were not, well now you know.

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