|SOLID PHASE EXTRACTION (SPE) OF PCBs & PESTICIDES FROM WATER MATRIX|
A state-of-the-art environmental laboratory was built at the University of Michigan (U-M) to measure organic and inorganic priority pollutants in water, soil, and air matrices. Sample preparation and measurement protocols approved by the Environmental Protection Agency (EPA) are being employed in the laboratory. This information guide describes a sample preparation methodology developed to measure polycholorinated biphenyls (PCBs) and pesticides in water matrix. The sample preparation was improved without changing the chemistry of the method and resulted in pollution prevention (P2) and waste minimization.
US-EPA SW-846 Third Edition Method 3535.
Overview of Procedure
The extraction methods approved by EPA and other agencies prior to 1986 often involved large sample volumes requiring significant quantities of chemicals and often chlorinated solvents, which result in prohibitively expensive waste storage, segregation, and disposal costs. Reduction of chemicals and solvents at the source would reduce the costs considerably.
Keeping the above objectives in mind, the U-M Occupational Safety and Environmental Health Environmental Laboratory developed an extraction procedure to determine PCBs and pesticides in water matrix which minimized costs in labor, reagents, materials, and waste disposal. Further, the procedure described herein led to increased safety in the laboratory.
For extraction of PCBs and pesticides from the water matrix, a procedure was developed based on EPA approved solid phase extraction (SPE) method, SW846 3535, which utilizes one liter of sample and less than 50 mL of solvents, methanol and methylene chloride. The SPE workstation has the capacity to process three samples simultaneously. The sample is filtered through a thin bonded polymeric disc using an aspirator vacuum, wherein the analytes of interest are trapped on the disc, and then extracted with 40 mL of methylene chloride directly into a 60 mL disposable vial. Utilization and subsequent cleaning of large 2 L separatory funnels and other glassware is completely eliminated. Three samples can be processed in 15 minutes or less saving considerable labor costs. SPE workstations with more than three positions are available for labs anticipating higher sample throughput.
Prepared samples are dried with a minimum amount of sodium sulfate, solvent exchanged for analysis by gas chromatography. The SPE procedure eliminates 90 percent solvents when compared with the conventional methods, exhibiting a significant reduction in purchase and disposal costs of chlorinated solvents such as methylene chloride. It also greatly increases safety in the laboratory by reducing potential exposure of workers to the solvents.
A standard operating procedure is available for this methodology that contains a section on P2 measures associated with this protocol.
& Health Precautions/Personal Protective Equipment
Project Related Costs