This European Standard specifies a method based on inductively coupled plasma optical emission spectrometry (ICP OES) for the determination of manganese content present as methylcyclopentadienyl manganese tricarbonyl (MMT 1)) in unleaded petrol from about 2 mg/l to about 8 mg/l. This test method is applicable to unleaded petrol containing up to 3,7 % (m/m) oxygen, including those with ethanol up to 10 % (V/V). NOTE 1 Manganese as MMT is added to petrol to increase anti-knock properties. WARNING — The use of this European Standard may involve hazardous materials, operations and equipment. This European Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this European Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. NOTE 2 Solutions of MMT in petrol are unstable when exposed to light. Low and erratic results are expected if petrol samples are exposed to light prior the analysis. NOTE 3 Manganese contents higher than 8 mg/l can be measured after preliminary dilution of the sample with a suitable solvent. However, the precision has not been established for such a procedure. NOTE 4 Application of the test method to the determination of other manganese compounds in petrol has not been tested. NOTE 5 For the purposes of this European Standard, the terms “% (m/m)” and “% (V/V)” are used to represent the mass fraction (µ) and the volume fraction (f) of a material respectively.