The ability of pyrolysis gas chromatographysingle bondmass spectrometry to quantify microplastics has been demonstrated; this study aims to provide a robust method using tandem mass spectrometry in order to gain in sensitivity and selectivity. The preparation of homogeneous and repeatable solid standards allowed us to perform an external calibration for six polymers in the nanogram range. Relevant indicator compounds were selected for each targeted polymer, and multiple reaction monitoring optimization was undertaken. The linearity, standard deviation and overall sensitivity were examined. After optimization, the detection limit was 15–70 ng according to the polymer. Interferences between polymers were examined, and we demonstrated that tandem mass spectrometry was necessary for the unequivocal detection of some polymers such as polyethylene and polypropylene. The method was applied to analyze the plastic particle content in bottled water. Only polyethylene terephthalate chemical compound was quantified at 42 ng.L-1. For future development, the use of internal standards will increase the method precision. It will also be important to better understand the interferences with the matrix in complex samples and the potential impact of weathering on the polymer pyrolytic response.