The future of fuels will most probably be a mixture of different fuels, called drop-in fuels. It is already known that these drop-in fuels will lead to solubility issues, with creation of deposit on crucial fuel system parts, due to the formation of soft particles. The fuel system of the future should be robust against any type of soft particles. Today, there is no scaled up test fluid existing for testing full scale fuel systems. The objective of this thesis was to develop a scaled up test fluid which is a key element to the development of a test method to enhance the fuel system robustness against soft particles. A test fluid was achieved by a concentrate of calcium soap diluted two thousand times to reach a volume of 1000 litres with a concentration of 1,4 ppm. The concentration was measured by gas chromatography mass spectroscopy method following a derivatisation as sample preparation. The formation of the concentrate was established by changing the type of fuel, the level of aging, the amount of calcium and other counterions and eventually by addition of third elements. The concentrate was made of aged B100, calcium oxide powder and water. The test fluid was made by diluting the concentrate with fresh B7 and a protocol to characterise the stability of this test fluid was developed. This test fluid was tested under real condition in a filter rig giving homogeneous concentration all along the experiment, which confirmed the stability of the test fluid.