Carbon Testing
Carbon Analysis & Techniques Used:
The carbon testing method in use is an upgraded form of that originally researched in Switzerland and marketed by various firms in the U.S. Fundamentally, the scheme involves combustion of a sample in ultra-pure oxygen at 990 deg C in a closed system.
The products (gasses) are swept through copper to remove excess Oxygen and silver salts to remove halogens, phosphorus, and sulfur. Since the heat conductivity depends upon it’s composition, the mixture of remaining gasses is sensed. The H2O is removed. Later the CO2 is removed and finally only N2 remains. Sensing is done after each removal.
The instrument is calibrated using various standards from the NIST. Thus all three elements can be determined in one run from the same sample selection. Running one sample at a time enables us to check for inorganic residue post combustion.
Interferences are very few. Very high fluorine levels (>60%) can cause high nitrogen results. This can be circumvented. The optimal sample size depends upon theory. It is always best that the analyst knows all elements present (the molecular formula). If completely unknown, the operator will select about 2 mg for analysis.
This equipment does well in the analysis of air-sensitive samples. These samples are sealed under nitrogen (in a controlled atmosphere) in preweighed capsules. (After removal from the glove box, the capsule is quickly inserted into the analyzer.)
This “special handling” process can be done in less than 4 minutes thus minimizing any degradation of the sample. There is a correction made for the increased nitrogen blank from the glove box gas.
What is Carbon?
Atomic weight 12.01, Atomic Number 6, Melting Point 3550 C, Boiling Point 4,827 C.
Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6. An abundant non-metallic, tetravalent element, carbon has several allotropic forms.
Carbon occurs in all organic life and is the basis of organic chemistry. This nonmetal also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly ten million known compounds.
When united with oxygen it forms carbon dioxide, which is vital to plant growth. When united with hydrogen, it forms various compounds called hydrocarbons which are essential to industry in the form of fossil fuels.
When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life, and esters, which give flavor to many fruits. The isotope carbon-14 is commonly used in radioactive dating.
Carbon is a remarkable element for many reasons. Its different forms include the hardest naturally occurring substance (diamond) and one of the softest substances (graphite) known. Moreover, it has a great affinity for bonding with other small atoms, including other carbon atoms, and its small size makes it capable of forming multiple bonds.
Because of these properties, carbon is known to form nearly ten million different compounds, the large majority of all chemical compounds. Carbon compounds form the basis of all life on Earth and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars.
Moreover, carbon has the highest melting/sublimation point of all elements. At atmospheric pressure it has no actual melting point as its triple point is at 10 MPa (100 bar) so it sublimates above 4000 K. Thus it remains solid at higher temperatures than the highest melting point metals like tungsten or rhenium, regardless of its allotropic form.
Carbon was not created during the Big Bang due to the fact that it needs a triple collision of alpha particles (helium nuclei) to be produced. The universe initially expanded and cooled too fast for that to be possible. It is produced, however, in the interior of stars in the horizontal branch, where stars transform a helium core into carbon by means of the triple-alpha process. It was also created in a multi-atomic state.
Relevant sites for Carbon:
Comprehensive information for the element Carbon – Properties of the element and much more…
