G.G. Hatch Stable Isotope Laboratory

Shipping:
25 Templeton Street
Advanced Research Complex
Faculty of Science
University of Ottawa
Ottawa, ON Canada
K1N 6N5
Attn: P. Middlestead

Find us at:
25 Templeton Street
Advanced Research Complex (ARC)
Room 426

For all inquiries click here.

Paul Middlestead, Lab Manager
pmiddle@uottawa.ca
Tel: (613) 562-5800
ext. 6839 (office)
ext. 6836 (lab)

Dr. Ian Clark, Director

Quantitative Analysis Techniques

 

Elemental Analysis using the VarioEL III or the Isotope Cube

Requirements for material sent for analysis:

  • Material must be ground to a powder.
  • Material must be dry.
  • Vials should be air-tight, especially when %H is required.

Requirements for pre-weighed samples sent for analysis:

  • Check with Lab personnel to determine the correct weight(s) to use.
  • Check whether WO3 is required, and how much.
  • Record the weights as accurately as possible, to 3 decimals (0.000mg).
  • Fill the sample trays across (A1, A2, A3, ...), from left to right.
  • Include the weight and the tray position for each sample in the submission file. The tray position can go in the comments column.
  • Make sure to squish the capsules into tight little balls; not flat or long.

Analysis Technique:

Elemental analysis is the determination of the elemental composition of organic or inorganic compounds.  The elementar VarioEL III is used in the G. G. Hatch Labs to determine %N, %C, %H, and %S; the Isotope Cube is currently configured for NC only.

Up to 500mg of powdered sample material can be measured into tin capsules .  Tungstic oxide which acts as a combustion catalyst is added to the capsules in the case of resiliant materials, such as salts, (inorganic) sulphur-bearing minerals or iron oxides.  The capsules are closed and re-weighed on the microbalance.  Calibrated sulfanilic acid standards are also prepared in a range of weights.

The prepared capsules are loaded into the carousel of the autosampler.  A sample falls down into the top of a column of solid chemicals at 1150°C or 925°C respectively, and is flash combusted at 1800°C with the addition of oxygen.  Ultra-pure helium is used to carry the resulting gases through the column of chemicals to obtain N2 , CO2 , H2O, and SO2 , then through a series of adsorption traps to separate the gases:  "purge and trap".  A thermoconductivity detector (TCD) measures the gases as they are released.

Elementar's own software that controls the EA's in stand-alone mode is also used to process the results from the TCD using the K-factor method.   The analytical precision (2 sigma) for the analyses is +/- 0.1%.

References:

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Last updated: 2013.05.02