NOVEL CONTAMINANTS IDENTIFIED IN FISH KILLS IN THE RED RIVER WATERSHED, 2011–2013

Provisional molecular weights and chemical formulas were assigned to four significant previously unidentified contaminants present during active fish kills in the Red River region of Oklahoma. The provisional identifications of these contaminants were determined using high-resolution liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS), LC-Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICRMS), and LC-ion trap mass spectrometry (LC-ITMS). Environmental water samples were extracted using a solid-phase extraction (SPE) method, and sediment samples were extracted using a modified sonication liquid extraction method. During screening of the samples, two major unknown chromatographic peaks were detected at m/z 624.3 and m/z 639.3. The peak at m/z 639.3 was firmly identified, through the use of an authentic standard, as a porphyrin, specifically chlorin-e6-trimethyl ester, with m/z 639.31735 (M+H)+ and molecular formula C37H43N4O6. The other major peak, at m/z 624.3 (M+H)+, was identified as an amide-containing porphyrin. It was discovered that the amide compound was an artifact created during the SPE process by reaction of ammonium hydroxide at one of three potential reaction sites on chlorin-e6-trimethyl ester. Other unique non-targeted chemicals were also detected and the importance of their identification is discussed. This article is protected by copyright. All rights reserved