Quantitative Analysis Techniques
Elemental Analysis using the VarioEL III or the Isotope Cube
Requirements for material sent for analysis:
Requirements for pre-weighed samples sent for analysis:
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%.