The steps to generate a measuring result can be very complex. Therefore, extensive sample preparation and sample conditioning are necessary. Each of these required steps increases the uncertainty of test results. However, these failures are not exactly quantifiable, because the true value is unknown. Nevertheless, this uncertainty must be calculated. For an analytical method, the uncertainty is nearly always well-known; because in this case the estimation is easily to perform by using standards of known concentration. It is significantly more complex to find the uncertainty of measurement if the parameters’ sample preparation and sample conditioning are included. In the course of this Master Thesis, the input of the sample preparation and sample conditioning were examined for two different preparation tasks. On the one hand, the step of the sample conditioning in form of a leachate of synthetically produced residual waste for the parameters of heavy metals, anionic tenside, conductivity, pH, total organic carbon (TOC), dry residue and anions was conducted. On the other hand, the influence of the sample preparation through the grinding of a sample made of stone likely material with a jaw crusher and a ball mill as well as the sample reduction using the quartering method for the parameters’ heavy metals and ash content was analysed. 20-25 synthetically produced samples were determined for each test series, so the influence of the inhomogeneity of the samples themselves could be eliminated. The collected data were analysed for various statistical evaluation. For the parameters ‘manganese in the stone samples’, as well as ‘nickel in the leachates’ and ‘chloride in the leachates’, the contribution of the sample preparation and sample conditioning to the measuring uncertainty were estimated. For all the other parameters the data base was created.