With the objective of optimising the measurement procedure, the influence of different operating parameters of a certification-like dilution mini-tunnel, such as the dilution ratio and the filtering temperature, is firstly presented in this paper. By means of an environmental chamber, both blank and charged filters were subjected to a range of different temperature and humidity conditions, as well as to different conditioning time periods. In all cases the weighted filters from the mentioned tests were subjected to a soxhlet extraction method, which permitted the chemical analysis of both the soluble organic fraction by gas chromatography and mass spectrometry, and the insoluble one by high performance liquid chromatography (HPLC) and infrared spectrography. Also the contribution of fuel and lubricant to the particulate matter was determined. All this information was related to the mini-tunnel operating parameters and to the ambient conditions.As a result of this experimental study some guidelines are given for measurement, handling and weighting of Diesel particulates in further particulate studies, as well as a quantification of the errors due to the tested variables.