Determination of the Congener Distribution in Aroclors to the Sub-ppm Level Coreen HamiltonKatharine Kaye Dale HooverBrian Fowler Axys Analytical Services, Ltd.

Presentation Outline 1.GOAL OF THE STUDY 2.ANALYTICAL APPROACH 3. DESCRIPTION OF METHOD 1668A 4.APPLICATION OF THE METHOD TO AROCLOR FORMULATIONS 5.RESULTS 6.CONCLUSIONS

Study Goals Determination of the congener composition of commercial Aroclor products.Determination of the congener composition of commercial Aroclor products. Input to risk assessment studies at contaminated sites.Input to risk assessment studies at contaminated sites. Both dioxin-like congener concentrations and other congener concentrations are of interest.Both dioxin-like congener concentrations and other congener concentrations are of interest.

Dioxin-like Congeners 12 “toxic” congeners12 “toxic” congeners Non-ortho substituted (coplanars): 77, 81, 126 and 169Non-ortho substituted (coplanars): 77, 81, 126 and 169 mono-ortho substituted 105, 114, 118, 123, 156, 157, 167, 189mono-ortho substituted 105, 114, 118, 123, 156, 157, 167, 189 Present in Aroclors at much lower concentrations (about 2 orders of magnitude lower) than the ortho-substituted congeners)Present in Aroclors at much lower concentrations (about 2 orders of magnitude lower) than the ortho-substituted congeners)

Analytical Approach “Concentrated” solutions ( ppm) of each Aroclor“Concentrated” solutions ( ppm) of each Aroclor “Dilute” solutions (5 to 10 ppm) of each Aroclor“Dilute” solutions (5 to 10 ppm) of each Aroclor Add 13 C labeled internal standardsAdd 13 C labeled internal standards Analysis by EPA Method 1668aAnalysis by EPA Method 1668a –SPB Octyl GC Column –DB1 GC Column –Fractionation on Carbon, DB1 GC Column

EPA Method 1668A Isotope dilution quantification for the 12 dioxin- like congeners and a few moreIsotope dilution quantification for the 12 dioxin- like congeners and a few more Internal standard quantification for all other congenersInternal standard quantification for all other congeners Low pg detection for dioxin-like congeners in all sample matricesLow pg detection for dioxin-like congeners in all sample matrices Minimizes interferencesMinimizes interferences

Application to Aroclors High concentration solutions to ensure detection of minor congenersHigh concentration solutions to ensure detection of minor congeners MS Source interferences when a large congener presentMS Source interferences when a large congener present Monitor lock mass channels and do not use impacted dataMonitor lock mass channels and do not use impacted data

Results Results 125 Congeners uniquely resolved on SPB Octyl GC Column125 Congeners uniquely resolved on SPB Octyl GC Column 185 Congeners uniquely or almost resolved on SPB Octyl plus DB-1 Columns185 Congeners uniquely or almost resolved on SPB Octyl plus DB-1 Columns Most dioxin-like congeners are always resolved and reliably quantified on SPB OctylMost dioxin-like congeners are always resolved and reliably quantified on SPB Octyl 77, 105, 114, 118, 167, 189, 156/157 (as a pair)77, 105, 114, 118, 167, 189, 156/157 (as a pair)

Interferences InterferencesPCB # Cl’s SPB Octyl (#Cl’s) DB-1 (# Cl’s) /115 (5) 86/125 (5) (5) 109 (5) /166 (6) 129 (6) 129 (6) /198 (6) 170 (7) 170 (7)

Results (cont’d) The 156/157 pair can be separated on a DB-1 columnThe 156/157 pair can be separated on a DB-1 column The four remaining dioxin-like congeners (81, 123, 126, 169) may need more workThe four remaining dioxin-like congeners (81, 123, 126, 169) may need more work Aroclor is a worst case situationAroclor is a worst case situation Depends on which AroclorDepends on which Aroclor

AROCLOR 1260 PCB-126 on SPB-Octyl GC Column Before Carbon Column Fractionation AROCLOR 1232 PCB-126 on SPB-Octyl GC Column No Carbon Column Fractionation AROCLOR 1260 PCB-126 on SPB-Octyl GC Column After Carbon Column Fractionation MASS: MASS: MASS:

AROCLOR 1260 PCB-129 on DB-1 GC Column Before Carbon Column Fractionation AROCLOR 1260 PCB-126 on DB-1 GC Column Before Carbon Column Fractionation AROCLOR 1260 PCB-126 on DB-1 GC Column After Carbon Column Fractionation MASS: MASS: MASS:

CONCENTRATIONS OF CONGENERS IN AROCLORS,ppm

PRECISION

ACCURACY Assumed to be high for the dioxin-like congeners due to isotope dilution technique.Assumed to be high for the dioxin-like congeners due to isotope dilution technique. Comparison to Aroclor data and toxicity data in the literature.Comparison to Aroclor data and toxicity data in the literature.

CONCLUSIONS CONCLUSIONS Use of HRGC/HRMS, carbon fractionation columns and multiple GC columns allowed isolation and quantification of dioxin-like congeners in eight Aroclor formulations.Use of HRGC/HRMS, carbon fractionation columns and multiple GC columns allowed isolation and quantification of dioxin-like congeners in eight Aroclor formulations. Quantification of dioxin-like congeners and total PCBs and was obtained from the same data set.Quantification of dioxin-like congeners and total PCBs and was obtained from the same data set.

CONCLUSIONS (cont’d) CONCLUSIONS (cont’d) Fractionation on carbon was needed for reliable quantification of some congeners.Fractionation on carbon was needed for reliable quantification of some congeners. A high degree of precision is achieved by use of isotope dilution quantification and HRMS, even for the low concentration dioxin-like congeners. Accuracy can only be inferred.A high degree of precision is achieved by use of isotope dilution quantification and HRMS, even for the low concentration dioxin-like congeners. Accuracy can only be inferred.

Acknowledgements Terry Smith, EPA Dale Rushneck, Interface, Inc.