Analysis of Persistent Organic Pollutants in Drinking Water with Semi-Automated Solid Phase Extraction

Challenges and Opportunities for Solid Phase Extraction
Poster Presentation

Prepared by , R. Addink

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


ABSTRACT

Continued interest in Persistent Organic Pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs), furans (PCDFs), biphenyls (PCBs), and Organochlorine Pesticides (OCPs) has led to a variety of automated systems for the Solid Phase Extraction (SPE) of various kinds of water samples, including drinking water. To meet demands for a lower cost method that requires less financial investment than the automated systems, we developed a simple semi - automated system which is faster and cheaper while yielding high quality data in accordance with EPA method 508, 1613 and 1668.

Six 1 L water samples were acidified to pH~2, spiked with 5-10mL methanol and 13C labeled standards. The sample bottles were attached to the SPE system and sample rinse bottles were filled with 25 mLs dichloromethane. C-18 cartridges were installed in each of the six positions.

The next steps were divided in two stages. Stage 1: cartridges conditioned under vacuum with dichloromethane, methanol and water (5 mLs each), followed by loading samples across cartridges, drying (nitrogen) and automated sample bottle rinse (dichloromethane). Stage 2: bottle rinses eluted across C-18 cartridges and Na2SO4 cartridges and eluent collected for analysis.

Collection tubes with Direct-to-Vial connections were put in an automated concentrator, pre-heated (15min, 50 °C), and heated in sensor-mode under 7-10 psi nitrogen which assured automatic shut-off at 1 mL. They were further reduced in volume (except OCPs) in a vial evaporator and spiked with recovery standards. Analyses were done on GC/FID and high res GC/MS.
Excellent 13C labeled recoveries were seen for tetra-CDD/Fs thru octa-CDD/Fs between 75-105%. For the WHO-12 and indicator PCBs the 13C recoveries were between 70-90%. For OCPs recoveries for ~ 22 analytes were 70-110%.
The semi-automated SPE system produces reliable and reproducible results for dioxins, furans and PCBs in drinking water. The system is cheaper than fully automated SPE equipment.