Aroclor Analysis and the Challenge of Matrix Interference “Using a Holistic approach in the Laboratory to analyze uncommon matrices with Confidence and Quality” Raymond Risden Technical Director Canton Laboratory March 2015 ©2014, TestAmerica Laboratories, Inc. All rights reserved. TestAmerica & Design ™ are trademarks of TestAmerica Laboratories, Inc.

2 Uncommon Matrices Most EPA methods have historically been developed for soil and aqueous matrices The need for aroclor determination has expanded to a much wider variety of sample types ~Caulk, sealants, concrete, asphalt, drywall, wood, construction debris, complex solvent mixes, oils, paint, insulation These samples present significant challenges, and adapting the analytical process is critical to produce data of high quality and compliance, while still supporting low action limits

3 Matrix interference Refers to components present in the sample extract other than the analytes of interest Matrix can interfere with the ability to reliably identify and quantitate analytes of interest ~Lead to false positive or negative results ~Lead to high or low bias of results In many cases this ultimately leads to performing a dilution which exceeds the required action limits

4 The Waldo Matrix

Overcoming the Matrix 5

The Holistic Approach The ability to overcome matrix challenges involves adapting the analytical process as a whole This includes adjustments or changes in: ~Sample prep and extraction ~Extract cleanup ~Analysis by GC 6

Sample Prep and Extraction Evaluating the matrix and applying the correct procedure to obtain a representative subsample must be done ~This may involve crushing, milling, grinding, cutting, sieving, etc. ~There is a lack of sound method guidance and many times the process is customized based on the sample ~Necessary to have a robust quality protocol when performing the subsampling to ensure process is free from contamination ~The Test America Canton Lab has an entire department with specialized equipment for PSR 7

Sample Prep and Extraction Matching matrix to the appropriate extraction technique is critical to ensure quality data as well as minimize matrix effects ~Soxhlet (3540) extraction is most effective for uncommon waste solids and is TSCA compliant ~Many labs utilize an inappropriate technique for the sample extraction that can have a profound effect on the quality and accuracy of the data ◦Sonication is not effective unless you can ensure sufficient sample particulate to solvent contact ( does not work for matrices such as caulk) ◦Need to be aware of the use of waste dilution ( 3580) on a matrix that is not 100% miscible in the solvent used ( paint chips are not amenable to this prep and can bias data low by orders of magnitude) Applying a solvent mix for the prep that minimizes coextracted interference is necessary ( 1:1 hexane /acetone is optimal for PCBs) 8

Extract Cleanup Applying a series of techniques to remove matrix interference from the extract without impacting the analytes of interest This is the most important application in the analytical process with uncommon matrices It is critical to ensure proper QC monitoring of the applications as many are very technique sensitive and can result in loss of target analytes The basis of all cleanups is utilize solvent or material that the interference has a higher affinity ( or to change the affinity) than the hexane based extract 9

Extract Cleanup Sulfuric acid/Permanganate cleanup (3665) ~Highly effective cleanup where oxidation/reduction chemistry is used to pull interference from the hexane extract into a polar solution Sulfur cleanup (3660) ~Utilizes TBA or activated copper to remove sulfur from extracts. Sulfur can significantly interfere with early eluting aroclors Solid Phase Extraction for cleanup ( 3620,3630,3610) ~Utilize silica gel, Florisil, or alumina to remove polar interferences and specific types of base/neutral compounds ~Very complex techniques that if not done correctly will result in loss of target analytes Gel Permeation Chromatography cleanup (3640) ~Removes interferences based on size, very effective on tissue samples or biotic based matrices 10

Extract Cleanup Many times exhausting all of the cleanup techniques is still not able to remove interference which can impact the ability to support low action limits for PCBs Currently developing and evaluating alternative novel cleanup techniques ~Use of activated carbon ~Dimethylformamide for waste oils ~Methanol/Water digestion of extracts ~Modification of solvent chemistries for SPE The cost and time can become extensive dependent upon the amount of cleanups that have to be utilized 11

Analysis by GC Multiple adjustments or different approaches can be applied with the actual analysis when cleanup techniques fail ~Exploiting the sensitivity of the instrument gives the lab a means to support action limits even when a dilution is necessary ◦Critical to ensure that this is demonstrated with proper MDLs and reporting limit verifications. Many labs run a lower standard without ensuring whole process can support lower sensitivity ~Incorporating a “post extraction spike” to demonstrate defensibility of a sample at the action limit when interference makes confident data evaluation uncertain ~Utilizing a more definitive confirmation technique such as mass spec 12

Analysis by GC Due to the extreme subjectivity of aroclor analysis and a lack of sound analytical guidance from the methods, analyst expertise is critical when evaluating complex chromatography Incorporation of peak resolution criteria and checks to ensure adequate separation of aroclor patterns Use of software that can evaluate identification of all peaks in a chromatogram with a mathematical confidence compared to actual standards (Test America Chrom) Use of an internal standard (not as common for aroclor analysis) can gauge matrix effects for every sample 13

Overlay of sample with matrix interference no cleanup 14

Overlay of same sample after multiple cleanup techniques 15

Overlay of MS on same sample after Cleanups 16

Overlay of sample where MS clearly defends matrix is not interfereing 17

Overlay of sample with significant matrix that can lead to false positive results 18

Summary for the data user Due to the impact, cost, and legality of PCB waste it is important for data users to understand how the analytical process can impact results ~Have confidence that the correct sample prep is applied ~Know that cleanups are performed with quality assurance ~Understand the analytical process must be able to defend the action limit 19

20 Questions