PARENT SESSION
MP5 - Applications of LC-MS in Environmental Analysis
Chair: Ferguson, Lee1, 1 SUNY - Stonybrook, Stonybrook, NY
Co-chair: Brownawell, Bruce2, 2 Stonybrook University, Stonybrook, NY
2:10 PM to 5:30 PM - Monday, 18 November 2002
Room Ballroom D
(288) Determination of alkylphenol ethoxylates in fish tissue and osprey eggs by LC/ESI-MS/MS.
Schmitz-Afonso, Isabelle*,1, Loyo-Rosales, Jorge2, Aviles, Maria de la Paz2, Rice, Clifford1, Rattner, Barnett3, 1 US Department of Agriculture, Beltsville, MD, USA2 University of Maryland, College Park, MD, USA3 USGS/Patuxent Wildlife Research Center, Laurel, MD, USA
ABSTRACT- Aquatic studies conducted over the past few years have shown the estrogenic effects and accumulation of nonylphenol (NP) and octylphenol (OP) and their respective lower ethoxylates (APnEOs) by several aquatic organisms. Several studies have shown their occurrence in river waters and sediments. Limited methods are available to look for these compounds in biota. Most of these involve GC/MS, for which the sensitivity progressively decreases with increasing ethoxy substitutions. Another technique is liquid chromatography with fluorescence detection which allows for the determination of NP and NPnEO up to n=5 and higher, but this technique cannot easily distinguish OPs from NPs. Liquid chromatography with tandem mass spectrometry provides both the specificity and the sensitivity to analyze for all these compounds. The LC/ESI-MS/MS method that we have developed uses ammonium adducts in positive mode and M-H- ions in negative mode. Using this method, we are able to quantitate all of the natural APnEOs (n = 0 to 5), the internal standards, n-NP, n-NP3EO and a series (n = 0 to 4) of 13C-labelled NPnEOs. With biota extracts, matrix effects have been observed to interfere as much as 50% when using negative mode to determining NP and OP in fish. Experiments performed to correct this problem included comparing Atmospheric Pressure Chemical Ionisation and Electrospray interfaces, using 13C-labelled internal standards and employing additional cleanup steps such as using C18 solid-phase extraction in different solvents for the fish and osprey eggs. These methods have been successfully applied to walleye from St Paul Metro, carp from Cuyahoga river and osprey eggs from Chesapeake Bay regions of concern. Quantification limits were 12ng/g for NP and OP and 4 ng/g for APnEOs in osprey eggs, they were 21ng/g for NP and OP and 6ng/g for APnEOS for fish samples.
Key words: LC/MS/MS, alkylphenol ethoxylates, osprey egg, fish