4.1 Identification of a recovered oil is determined by comparison with known oils, selected because of their possible relationship to the particular recovered oil. The known oils are collected from suspected sources. Samples of such known oils must be collected and submitted along with the unknown for analysis. At present, identification of the source of an unknown oil by itself cannot be made (for example, from a library of known oils).

4.2 The use of a flame-photometric detector in addition to the flame-ionization detector provides a second, independent profile of the same oil, that is, significantly more information is available from a single analysis with dual detection.

4.3 Many close similarities (within uncertainties of sampling and analysis) will be needed to establish identity beyond a reasonable doubt. The analyses described will distinguish many, but not all samples. For cases in which this method does not clearly identify a pair of samples, and for important cases where additional comparisons are needed to strengthen conclusions, other analyses will be required (refer to Practice D3415). In particular, Practice D5739 is useful for such cases.