Carbon capture and storage has gotten increased attention during the last decade, and several full-scale projects are currently being planned. This requires transportation of large quantities of CO2 from the capturing plant to the end point. From economic and public acceptance point of view it is important to ensure that the transportation system is operated in a safe manner. Thus, avoiding threats like corrosion or formation of particles are important. It is therefore required to monitor that the transported CO2 fulfils the required specifications, and in practice this means that the impurity content of the CO2 must be analysed. CO2 will in most cases be transported in the liquid or supercritical state (high pressure), which makes the practicalities around chemical analysis more difficult. Phase transition from liquid or supercritical state to gaseous state may also introduce several physiochemical effects that may affect the analysis. This paper discusses technical and practical challenges with such types of analysis. Most of this work is based on experience that was gained during development of analytical system for dense phase CO2 in a joint industry project that studied corrosion and chemical reactions in a simulated CO2 transport system.