A quick cogener specific analysis of polychlorinated biphenyls in municipal sludge utilizing ultrasonic extraction and capillary gas chromatography
- Madison Metropolitan Sewerage District, Madison, WI (United States)
At the Madison Metropolitan Sewerage District (MMSD) land application is a routine procedure for recycling municipal digested sludge. In 1982 analyses performed by MMSD indicated some areas of the sludge storage lagoons had polychlorinated biphenyl (PCB) levels greater than 50 parts per million (ppm), the EPA established limit for unrestricted land application of sludge. Conflicting test results obtained from commercial laboratories prompted MMSD to find the most reliable test method and also maximize the amount of information received from each analysis. Therefore, an accurate and precise measurement of PCBs in sludge was desired on a daily and sometimes hourly basis. Analysis of sludge samples by soxhlet extraction (SW846 method 3540B) and capillary gas chromatography (GC) required overnight extraction, 2-3 hours extract cleanup and concentration, plus 3 hours elution time on a narrow bore column to achieve a congener specific analysis. A procedure to obtain congener specific PCB data in 2-2.5 hours was developed using ultrasonic extraction (SW846 method 3550B), florisil mini-cartridge cleanup and a 20-meter narrow bore column. Small homogeneous samples of sludge (2-4 grams) were mixed with the extracting solvent in a 50 mL centrifuge tube and then extracted using a sonic dismemberator in the pulsed mode. A 20-meter length was cut from a 60-meter, 0.25 mm i.d. capillary column. Resolution of some of the 95 congeners present was sacrificed to obtain a GC run time of 23 minutes. Sludges ranging from 2% to 30% solids were routinely analyzed with concentrations from detection limits to 200 ppm dry weight. Comparison of the sonication vs. soxhlet extractions exhibited no significant difference in the amount of PCBs recovered from various samples.
- OSTI ID:
- 191669
- Report Number(s):
- CONF-941098--
- Country of Publication:
- United States
- Language:
- English
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