“…Although wear metal particles are not uniformly distributed in oil, they are generally determined by using techniques traditionally applicable to the determination of metals in homogeneous solutions. Atomic absorption spectrometry (AAS), rotating disk electrode atomic emission (RDEAE), inductively coupled plasma (ICP), and direct current plasma (DCP) techniques have been used for the determination of wear metals in used lubricating oils (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Even though plasmas produce higher temperatures than flames and arcs, our previous work showed that analyses of oils containing particles larger than, ca., 3-10 pm, are, in general, not quantitative (3,5,7).…”