The sources of uncertainty affecting measurements of pollutants include sample collection, handling and stocking, and analytical procedure. With regard to chemical analysis, MS detection offers a series of advantages for resolving complex mixtures and identify and quantify analytes present at very small extents. Nevertheless, it presents some problems of reproducibility, which can affect the quality of quantitative data. PAH represent key-compounds among atmospheric pollutants and are usually evaluated by means of dedicated methods comprising MS detection. Based upon the above considerations, an analytical method has been standardized, suitable for determining PAH in atmospheric aerosols and diesel particulate exhausts. To test the procedure, both diesel particulate and urban aerosol NIST reference materials (SRM-2975 and SRM-1649A, respectively) have been processed and the results have been compared with certified and/or literature data. The results obtained are shortly discussed.