MEASUREMENT OF TRACE ELEMENTS IN PROCESSED FUEL OILS PRODUCED FROM RECYCLED LUBRICATING OILS

摘要

The recently published UK Environment Agency Quality Protocol for Processed Fuel Oils1 includes specifications for maximum concentrations of thirteen trace metals with limits down to 5 mg/kg. Not all of these metals specified in the Quality Protocol could be measured in these materials at the required levels using existing Standard Test Methods. In particular, the residual type PFOs (currently the most commonly produced), present particular analytical challenges in view of the inhomogeneous nature of the samples and the fact that many of the metals are present in the samples in the form of particulates. The analytical challenges are compounded by the requirement to measure potentially volatile elements such as Hg, As and Tl which are easily 'lost' during the ashing step typically used in conventional test methods for determination of metals in this type of sample (e.g. IP 501~2). This paper describes the development of three new Standard Test Methods for measuring trace elements in residual PFOs. IP 592~2 and IP 593~2 for measurement of Pb, Ni, Cr, Cu, Zn, As, Cd, Tl, Sb, Co, Mn and V using microwave digestion ICPMS and WDXRF respectively; and IP 594~2 for determination of Hg using combustion, amalgamation, cold vapour atomic absorption spectrometry (CVAAS). The relationship between the methods and comparisons with traditional approaches such as IP 501~2 will also be discussed. In view of the urgency of the requirement for suitable test methods to meet the requirements of the Quality Protocol1, the complete project from initiation, ruggedness trail, inter-laboratory study and publication of the final methods was completed in less than one year.