AbstractThis study reports the occurrence and distribution of organophosphor esters (OPEs), used as flame retardants and plasticizer, in the marine atmosphere of the German Coast. From August 2011 to October 2012, 58 high volume air samples (gas/particle phase separately) were collected at the German North Sea coast town Büsum. With the use of a GC-MS/MS System for instrumental analysis, detection limits for OPEs in air samples could be significantly improved compared to the previously used single GC-MS method. The concentration (gas + particle phase) of total OPEs was on average 5 pg/m3, with eight of the nine investigated compounds detectable in over 50% of the samples. A focus of this investigation concerned the partioning of OPEs between the particle and the gas phase. The observed partitioning of OPEs in this study was distinguished from previous studies. While previous studies reported OPEs exclusively in the particle phase, a significant part of the sum OPE concentration (55%) was detected in the gas phase. The contribution of the gas phase even reached up to as high as 88% for individual compounds such as tri-iso-butyl phosphate.