Determination of phosphorus in lubricating oils by cool-flame emission spectroscopy.
The phosphorus content of lubricating oils is determined by measurement of the emission from the HPO molecular species at 528 nm in a cool hydrogen-nitrogen diffusion flame. The oil is ashed in the presence of potassium hydroxide and an aqueous extract of the melt is treated with ion-exchange resin to remove interferents, before aspiration into the flame. Analytical results are presented on samples containing phosphorus in the range 0.009-0.2%. The precision of the method is +/- 5% at the 0.04% phosphorus level.
Elliott
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Quality Assurance Directorate (Materials) Royal Arsenal London, S.E.18U.S.A.
Heathcote
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Mostyn
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