|Method||Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES)|
|Standards||ASTM D 5185|
Used for the determination of quantities of metals in samples of lubricants and fuels. When combined with acid digestion techniques, it can also be used for analysis of greases, coolants and many more sample types.
A portion of the sample is mixed with solvent and agitated to homogeneity (uniformity). At which point argon gas is passed through a torch assembly surrounded by an induction coil that electrically excites the gas, creating a plasma. The test specimen is then pumped into the sample introduction system, converted to aerosol and directed into the plasma via the torch.
Individual atoms within the sample are excited by interaction with the plasma, entering a high-energy state.
Energy from these excited atoms is then rapidly lost, with the product of this energy loss being the emission of light.
A CCD sensor then detects this light, via a series of optics, across a range of wavelengths.
Different atoms emit different wavelengths of light during this process. It is from the magnitude of light detected at given wavelengths that tells us the concentration of each atomic species present.
Testing the samples against a variety of calibration standards, the final output of the technique is a ppm value (Parts Per Million, also referred to as mg/Kg) for each specified element, with quantification of levels of above 1ppm for most elements.
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