A　method　for　the　analysis　of　polychlorinated　biphenyls　(PCBs)　and　polybrominated　diphenyl　ethers　(PBDEs)　in　serum　was　developed　using　gas　chromatography　coupled　to　tandem　mass　spectrometry　with　atmospheric　pressure　chemical　ionization　(GC-APCI-MS/MS).　The　ionization　and　fragmentation　performance　of　APCI　were　evaluated　and　compared　with　those　of　electron　ionization　(EI).　In　contrast　to　extensive　fragmentation　caused　by　El　with　high　energy,　soft　ionization　achieved　by　APCI　produced　mass　spectra　dominated　by　molecular　ions　from　the　first　stage　of　MS　analysis.　Better　sensitivity　and　selectivity　achieved　by　the　GC-APCI-MS/MS　method　allowed　to　analyze　serum　samples　with　a　low　volume　(100　mu　L).　The　limits　of　detection　(LODs)　ranged　from　0.067　to　14　pg/mL　for　the　analysis　in　serum　samples.　The　developed　method　was　evaluated　at　three　spiking　levels　(0.05,　0.5　and　5　ng/mL　for　PCBs),　showing　good　recoveries　and　repeatability.　The　recoveries　ranged　from　74.0%　to　130.5%,　and　the　relative　standard　deviations　(RSDs)　were　less　than　20%,　for　all　analytes.　The　determination　of　PCBs　and　PBDEs　in　the　human　serum　samples　by　GC-APCI-MS/MS　was　compared　with　gas　chromatography　-tandem　mass　spectrometry　with　El　(GC-EI-MS/MS).　BDE-99　and　BDE-100　were　successfully　quantified　by　GC-APCI-MS/MS,　while　these　two　PBDE　congeners　were　not　detected　by　GC-EI-MS/MS.　The　GC-APCI-MS/MS　method　had　a　clear　advantage　when　analyzing　compounds　at　low　levels.　(C)　2019　Elsevier　Ltd.　All　rights　reserved.