The method established by this standard is used to determine the chlorine content of lubricating oils and their additives by means of X-ray fluorescence analysis. For this purpose equal masses of the sample and a bismuth solution as a reference substance are mixed and thenexposed to the primary radiation of an X-ray tube. Subsequently the impulse rates of the X-ray fluorescence radiations of C1-Kalpha and Bi-Mbeta are measured. From this the ratio of the impulse rates can be calculated. The percentage of chlorine in the sample expressed as mass fraction in % is determined with the help of reference curves established with chlorine reference solutions.