IP10 Emerging Issues in Analytical Chemistry
B115 & B116
1:20 PM - 4:40 PM, Wednesday
(IP083) Analysis of Recovery Determinations for Dioxin with the CALUX® Bioassay.
Clark, George1, Chu, Anderw1, Gordon, John1, Brown, David1, Nakamura, Masafumi 2, Chu, Michael3, Denison, Michael4, Murata, Hiroshi2, 3, 1 Xenobiotic Detection Systems, Inc., Durham, NC, USA2 Hiyoshi Corporation, Omihachiman, Shiga, Japan3 Alta Analytical Perspectives, Wilmington, NC, USA4 Dept. of Environmental Toxicology, Univ. of California, Davis, CA, USA
ABSTRACT- Analysis of recovery determinations are very important for quantitative methods such as high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) as well as bio-analytical methods such as CALUX® for dioxins. Recovery determinations in HRGC/HRMS are performed by spiking isotopically labeled congeners into the sample prior to extraction, with recovery based on the amount of labeled compound recovered. Bioassays do not differentiate between isotopically labeled and unlabeled analytes. Therefore, recovery determinations in bioassays can be accomplished with a surrogate sample spiked with a radiolabeled congener of dioxin. We demonstrate here that 1,2,3,4-TCDD, a biologically inactive congener of the dioxin family of chemicals, can be used as an internal spike to determine recoveries of dioxin-like chemicals. Samples were spiked with 14C labeled 2,3,7,8-TCDD or 1,2,3,4-TCDD and submitted to extraction and clean up using Xenobiotic Detection Systems, Inc. patented XCARB sample clean up method (acid silica column in series with an XCARB column) (patent no. 6,720,431). The XCARB column is differentially eluted to yield a PCB and PCDD/F fraction. The 1,2,3,4-TCDD spiked samples were resuspended in toluene containing four PCB injection standards, and recoveries determined by gas chromatograph with electron capture detection or scintillation counter. Average recoveries determined by 1,2,3,4-TCDD with paired samples spiked with 14C- 2,3,7,8-TCDD indicated that the recoveries determined by the two methods were very similar, 88.5% (± 1.2%) and 87.2% (± 2.4%), respectively. Recovery determinations were also verified by HRGC/HRMS. This procedure allows for quantitative determination of dioxin-like chemicals in various sample matrices. Supported by SBIR Grant from NIEHS ES 08372-03.
Key words: Dioxin, CALUX, PCB, Bioassay