Under the assumption of the imaginary company Dextras, operating a GMP-certified laboratory, and currently pursuing GLP-standard, this bachelor-thesis focuses on the introduction of the GCP-standard into the operation – particularly focusing on the requirements for bioanalytical method validation on the basis of an exemplary mass-spectrometric method for the analysis of clinical samples. The samples are derived from an imaginary clinical trial, testing cis-platinum-cytostatic drugs, and the mass fraction of platinum in each sample has to be determined, using mass spectrometry. The experimental aspects of this method validation are illustrated in the form of an SOP. The different properties selectivity, lower limit of quantification, carry-over, the response function and calibration range (calibration curve performance), accuracy, precision, matrix effects, dilution integrity, and stability of the analyte in the biological matrix under the entire period of storage and processing conditions are being validated, thereby utilizing different concentration standards – quality control samples (QC samples) – in a process of repeatingly comparing the measured values with the nominal- or mean values of the concentration level. The primary objective is to comply with universal-, and at the same time sophisticated guidelines, by applying the highest possible scientific expertise in order to achieve an optimum conformity.