Semi-Automated Solid Phase Extraction and Analysis of Wastewater with EPA Method 625

Automation & Innovation for Sample Preparation
Oral Presentation

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


Contact Information: [email protected]; 617-393-2396

ABSTRACT

Solid Phase extraction has long been used for the analysis of semi-volatile organics in clean matrices. Methods like EPA 525.3 and EPA 625 outline performance data for a variety of analytes and products. Due to the unique challenges inherent with wastewater matrices laboratories have predominately adhered to LLE (Liquid-Liquid Extraction) protocols. Recent advances in packing materials and semi-automated extraction systems have now made once unheard-of extractions of matrices commonplace for SPE.

To meet demands for a low-cost method that requires less financial investment than fully automated systems, a simple semi - automated system was developed which is fast, inexpensive and yields high quality data.

Twelve samples (1 L water) were prepared and acidified with HCl till pH ~ 2, spiked with various 625 standards and put in sample bottles. Rinse bottles containing 35 mL dichloromethane were installed. Mixed bed and coconut charcoal cartridges were used. The vacuum was turned on and cartridges were conditioned with dichloromethane, methanol, and water, followed by sample loading (vacuum). The cartridges were then dried, sample bottles rinsed with dichloromethane, which was then loaded across the mixed-bed cartridges (eluent collected as acidic Fraction # 1) followed by an additional 15 mLs dichloromethane. The mixed-bed cartridges were then conditioned with 1% sodium hydroxide and eluted with dichloromethane (basic Fraction # 2). The coconut charcoal cartridges were then eluted with dichloromethane which was added to Fraction # 2. Extracts were dried over in-line sodium sulfate cartridges.

GC/MS analysis showed that recoveries were all well within the acceptance QC limits for wastewater matrices. Analysis of additional analytes showed this application is also suitable for analytes beyond those with QC criteria specified by the method.