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SUBCRITICAL (HOT) WATER/ETHANOL EXTRACTION OF NONYLPHENOL POLYETHOXY CARBOXYLATES IN INDUSTRIAL AND MUNICIPAL SLUDGES. (R821195)
Citation:
Reed, R. L. AND J. A. Field. SUBCRITICAL (HOT) WATER/ETHANOL EXTRACTION OF NONYLPHENOL POLYETHOXY CARBOXYLATES IN INDUSTRIAL AND MUNICIPAL SLUDGES. (R821195). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 33:2782-2787, (1999).
Description:
Subcritical (hot) water with ethanol as modifier was used
to extract nonylphenol polyethoxy carboxylates (NPECs)
with 1-4 ethoxy groups from sludge samples. Quantitative
recovery of native NPECs from sludge was accomplished
by extracting 0.25 g samples for 20 min with 30% (v/v)
ethanol in water at 75 
C and 150 bar. NPECs in the water/ethanol extract were concentrated by a strong anion
exchange (SAX) Empore disk. The NPECs were simultaneously
eluted and derivatized to their methyl esters in an
autosampler vial. Although carbon dioxide, hot water, and
methanol-modified hot water were evaluated for NPEC
recovery, ethanol-modified hot water yielded the highest
recovery of native (unspiked) NPEC from sludge. Samples
analyzed for this study included an anaerobically-digested municipal sludge, a commercial product containing
anaerobically-digested municipal sludge and yard waste,
and secondary clarifier sludge obtained from a paper mill.
NPEC concentrations ranged from 27 to 113 
g/g with
NP2EC as the most abundant oligomer. Samples of
anaerobically-digested sludge had ortho-to-para isomer
ratios 
1, which indicated the depletion of para NPEC
isomers relative to ortho isomers during anaerobic sludge
treatment. In contrast, secondary clarifier sludge from a
paper mill that had not undergone anaerobic treatment
contained only para NPEC isomers.