USE OF THE SEMIPERMEABLE-MEMBRANE DEVICE AS AN IN-SITU SAMPLER OF WATERBORNE BIOAVAILABLE PCDD AND PCDF RESIDUES AT SUB-PARTS-PER-QUADRILLION CONCENTRATIONS

Semipermeable membrane devices (SPMDs) were used to passively sample a queous polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated d ibenzofurans (PCDFs) in Bayou Meto, AR. The two sites were upstream an d downstream from the confluence with a tributary that delivers PCDDs and PCDFs to the Bayou. Following dialysis, cleanup, and fractionation , four replicate 17-g SPMD samples from each site were analyzed by GC/ MS, and four were evaluated by H4IIE bioassay. Traces of only OCDD and HpCDDs were detected in samples from the upstream site. The four samp les from below the tributary contained averages of 1550 +/- 80 pg of 2 ,3,7,8-TCDD, 1640 +/- 80 pg of 2,3,7,8-TCDF, and lesser quantities of other congeners. The TCDD equivalents obtained by bioassay of replicat e SPMD samples agreed well with results obtained by GC/MS. The quantit ies of 2,3,7,8-TCDD and 2,3,7,8-TCDF sequestered by SPMDs at the downs tream site were used to estimate the aqueous concentrations for both c ompounds as 2 mu g/L.