We are developing a certified reference material for the accurate quantification of polycyclic aromatic hydrocarbons (PAHs) at trace levels (< 1 µg/g). PAHs are formed through incomplete combustion and are transported for long distances. It is therefore necessary to monitor the levels of emitted PAHs not only in highly contaminated samples, but also in less-contaminated environmental samples. To develop matrix-type certified reference materials, isotope-dilution mass spectrometry (IDMS) is commonly applied for the accurate quantification of not only PAHs but also other pollutants. The IDMS method is based on the principle that internal standards with stable isotope behave in the same manner as the target (native) compounds throughout analytical processes. However, it is not true for the quantification of PAHs at trace levels using deuterium-labeled PAHs although this is true for those at high levels (> 1 µg/g). In the light of this fact, we used ¹³C-labeled PAHs as internal standards to develop the matrix-type certified reference material of PAHs at trace levels.