Novel Dechlorane Analogues and Possible Sources in Peregrine Falcon Eggs and Shark Livers from the Western North Atlantic Regions

Abstract

During the investigation of dechlorane-related chemicals in North American wildlife, two unknown polychlorinated compounds (referred to as U1 and U2) were discovered. After extensive sample cleanup, structural information on U1 and U2 was characterized by gas chromatography (GC) coupled with single quadrupole mass spectrometer (MS) or GC-quadrupole time-of-flight (QToF) MS. Mass spectral evidence suggests that both U1 and U2 are structurally related to Dechlorane 603 (Dec603; C17H8Cl12), an analogue of the chlorinated flame retardant Dechlorane Plus. From the results we suspect U1 (C17H9Cl11) to be a monohydro analogue of Dec603 (i.e., one chlorine atom in Dec603 is replaced by a hydrogen atom). U1 may be formed via the degradation of Dec603’s stereoisomers or present as an impurity in commercial Dec603 products. Mass spectral characterization of U2 (C17H7OCl11) suggests it is a carbonylic derivative of Dec603, likely formed via metabolic transformation of Dec603 or its photoisomer. Semiquantitative measurement revealed that U1 and U2 were present at estimated median concentrations of 49 ng/g lipid weight (lw) and 59 ng/g lw in peregrine falcon (Falco peregrinus) eggs, from the mid-Atlantic region of the United States, and 4.6 and 3.0 ng/g lw in shortfin mako shark (Isurus oxyrinchus) livers from the western North Atlantic Ocean, respectively. Our results demonstrate the occurrence of these two novel Dec603-related chemicals in both terrestrial and aquatic ecosystems.

Biomagnification and Temporal Trends of New and Emerging Dechloranes and Related Transformation Products in Baltic Sea Biota

“…Only two Dec603 TPs had previously been reported, a monohydro-Dec603 and its carbonyl, in a study where they were denoted U1 and U2. 13 The remaining Dec603-related compounds were assigned as a Dec603 isomer, a dihydro-Dec603 (possibly a monohydro-TP of U1), three dihydro-Dec603 carbonyls (possibly monohydro-TPs of U2), two trihydro-Dec603 dicarbonyls, and one hydroxyl-Dec603. Liu et al suggested (but did not confirm) that the latter may be an intermediate in the transformation of Dec603 to U2.…”

“…Liu et al suggested (but did not confirm) that the latter may be an intermediate in the transformation of Dec603 to U2. 13 They suggested that Dec603 is dechlorinated to monohydro-Dec603 (U1), hydroxylated to hydroxyl-Dec603, and further oxidized to U2. It is plausible that trihydro-Dec603 dicarbonyls are formed by further dechlorination and oxidation of monohydro-U2.…”

“…U1 and U2 refer to a monohydro-Dechlorane 603 isomer and its carbonyl oxidation product identified in a previous study. 13 …”

“… 10 It also showed that these compounds undergo dechlorination (forming mono- or dihydro-analogues) 11 − 15 and oxidation (forming carbonyls). 13 This prompted suspect screening of dechloranes, hydrodechloranes, and carbonyl and hydroxyl transformation products (TPs) of dechloranes and hydrodechloranes. Screening of samples collected in recent years revealed the presence of several new and emerging dechloranes in Baltic Sea biota.…”

Characterization of Halogenated Organic Compounds in Pelagic Sharks and Sea Turtles Using a Nontargeted Approach

“…One possibility is that the observed m/z ion clusters of these two compounds were not molecular ions. Liu et al 77 reported two unknown compounds that are structurally related to Dechlorane 603 in peregrine falcon eggs and shark livers from the western North Atlantic regions. The C 17 H 9 Cl 10 detected in the current study has a similar MS profile as one of the unknowns (C 17 H 9 Cl 11 ) proposed by Liu et al 77 Two features observed at MD = 0.40 had a 78 mass unit difference (m/z 382 and m/z 460) and were assigned formulas C 17 H 10 Cl 4 N 2 and C 17 H 9 BrCl 4 N 2 , respectively.…”