PH06 Agrochemicals, Pesticides, Pharmaceuticals
Exhibit Hall
8:00 AM - Thursday
(PH046) Method for the definitive analysis of diphacinone in exposed coconut crabs (Birgus latro).
Tanner, M1, 2, Orazio, C2, Steiner, W3, 1 AScI, Inc., Tallahassee, FL, USA2 USGS-BRD-Columbia Environmental Research Center, Columbia, MO, USA3 USGS-BRD-Pacific Island Science Center, Honolulu, HI, USA
ABSTRACT- The use of diphacinone (2-diphenylacetyl-1,3-indandione) for the control of Polynesian rats (Rattus exulans) in the Commonwealth of the Northern Mariana Islands, American Samoa, and other South Pacific islands is being considered by the U.S. Fish and Wildlife Service (USFWS). To determine if diphacinone residues persist in the food chain and pose a potential contamination threat to the coconut crab (Birgus latro), an important food source to indigenous populations, the USFWS and U.S. Geological Survey conducted a study where coconut crabs were fed 24-hour and 48-hour diphacinone-exposed euthanized rats and 0.005% diphacinone bait blocks. The left claw muscle and hepatopancreas from individual crabs were analyzed for diphacinone residues. A confirmatory method for analysis of diphacinone residues at a limit of quantification of 0.01
g/g (wet weight) was developed using solid phase extraction (SPE) cleanup followed by high performance liquid chromatography (HPLC) with diode array detection (DAD). Diphacinone was isolated by acetonitrile column extraction of sodium sulfate dried sample tissues; followed by SPE separation of diphacinone from the co-extracted acetonitrile soluble lipids using two 1g C18 cartridges; and quantitation by HPLC-DAD. The HPLC-DAD method provided confirmatory UV spectra for comparison to diphacinone standards. Quality control was maintained throughout the study with procedural and matrix blanks to determine diphacinone background and laboratory-fortified matrix spikes to determine method extraction efficiencies. The method was validated with laboratory-fortified snow crab tissues. Applying the validated method to the coconut crab study tissues, trace levels of diphacinone residues were quantified in five individuals from the bait block diet group (claw muscle: 0.02g/g to 0.14g/g and hepatopancreas: 0.05g/g to 0.36g/g). Two individuals from the 48-hour rat diet group showed traces of diphacinone in claw muscles (0.02g/g to 0.03g/g), and one showed diphacinone residues in the hepatopancreas (0.09g/g). Recoveries of laboratory-fortified diphacinone from sample matrices were 98% to 104%.
Key words: coconut crab (Birgus latro), diphacinone, SPE, HPLC-DAD