This part of ISO 8573 specifies the test method for determining the content of oil vapour in compressed air using pressurized sampling and gas chromatography. This part of ISO 8573 elaborates sampling, measurement, evaluation, uncertainty considerations and reporting in respect of the compressed air purity class for oil, in accordance with ISO 8573-1. NOTE 1 For organic vapours and other gaseous contaminants, the same sampling procedure can be used, however the analysis method will be different depending on the target component. As guidance, ISO 8573-6 and ISO 16000-6 can be used. NOTE 2 It is required to do a measurement of oil aerosol according to ISO 8573-2 and an oil vapour according to ISO 8573-5 for claiming an oil purity class 0, 1 or 2, according to ISO 8573-1.