Quick and Reliable Method for Cleanup of All 209 PCBs in One Fraction in Environmental Samples

New Organic Monitoring Techniques
Oral Presentation

Prepared by T. Hall, R. Addink
Fluid Management Systems, 900 Technology Park Dr, Billerica, MA, 01821, United States


Contact Information: thall@fms-inc.com; 617-393-2396


ABSTRACT

The Stockholm Convention on Persistent Organic Pollutants (2004) has led to a steady demand for environmental lab analyses around the world, including Polychlorinated Biphenyls (PCBs). In North-America environmental laboratories are often processing samples for all 209 PCBs with a desire to collect all analytes in this compound class in one single fraction to simplify GC/MS analysis.

We developed a method combining features of automated and manual techniques: - accurate, fast, reliable with short turnaround times and low background using pre-packaged columns. Samples can also be in 2-10 mL toluene with this cleanup method which is important since many labs extract their samples in toluene with the Soxhlet technique. Subsequent cleanup in toluene eliminates the necessity for solvent exchange to hexane.

The method uses a system mounted on a turntable which can be rotated 180 degrees. A vacuum pump is used for conditioning, sample loading, and elution. Columns used are acidic silica and alumina which are placed on top of each other. The columns are conditioned with hexane, followed by sample loading onto the silica (Fraction # 1). Subsequent steps - elution with hexane and 10% dichloromethane/hexane - are also collected in Fraction # 1. At this point all 209 PCBs have been collected in the same fraction. Total volumes vary between 100-200 mLs. Automated concentration/evaporation at 55 oC and 6-8 psi nitrogen takes the samples down to 0.5 or 1 mL followed by final reduction in a vial evaporator to 20 uL. Use of Direct-to-Vial connections eliminates the need for manual sample transfer.

Cleanup with this system of salmon and soil extracts yielded consistent results with recoveries between 70-90 %. The system can run 6 samples in parallel and fits easily in an average size lab hood. With maximum processing times of 60-80 min same-day PCBs analyses are easily achieved.