Because the aim of the analysis lubricating oils is to monitor the oil of an engine and get a trend analysis over time, the best accuracy is not required. The trend analysis allows the analyst to see that the oil is changing and when the engine needs stripping down before a catastrophic failure. The use of the internal standard is not required because the results are only compared to previous results. The procedure is thus very simple: new two point calibration each time the sample is analyzed and dilution of the samples by 1:5, 1:10 or 1:100, depending on the viscosity of the oil samples and whether lower detection limits are required. 高性能ICP光譜儀