One aim of nuclear forensics is to establish the origin of nuclear material used in criminal activities. For uranium characteristics such as age, i.e. the time passed since last chemical separation, isotopic composition and solid phase morphology, can be used to discriminate between different materials and determine e.g. the production process and thus where the material may originate from. Other characteristics are the impurities that follow the uranium through the nuclear fuel cycle processes. One such group that may be used is the lanthanides. All lanthanides have similar chemical and physical properties and are hence expected to, to the same extent, follow the process of producing nuclear fuel. The composition of lanthanides differs depending on geographical origin and may therefore be used for origin assessment. The amount of lanthanides in uranium is relatively low; therefore ICP-SFMS is a suitable measurement technique. To avoid interferences from the relatively large amount of uranium, the samples are chemically separated to remove the uranium from the lanthanides prior to measurement. The aim of this work was to investigate the possibilities and difficulties of measuring lanthanides in uranium material. The report shows that lanthanide measurements using ICP-MS suffer from isobaric and polyatomic interferences that need to be minimised in order to acquire correct results but also that there are good possibilities to avoid these, either by modifying a separation method that divides interfering lanthanides into different fractions or by correcting for the existing interferences, or by a combination of both.