Wastewater is an important area in environmental analysis but represents a challenge for sample preparation. Wastewater matrices are complicated to analyze due to suspended solids, surfactants, and high concentration of total organic carbon. Various filtration and solid phase extraction (SPE) systems were tested using municipal wastewater from the City of Chicago to concentrate pharmaceutical compounds including antidepressants (fluoxetine, norfluoxetine, sertraline, norsertraline, bupropion<b>,</b> venlafaxine, citalopram, duloxetine, and paroxetine) and carbamazepine. Comparative analysis was done using 500 mL wastewater samples that were vacuum filtered with commercial filter products which included GF, 3, and 45 mm filter paper. Isotopic standards were added to each sample to quantitate percent recovery of pharmaceuticals. For SPE, 3cc-60mg and 6cc-200mg Oasis® HLB cartridges containing a polymeric reversed-phase sorbent were tested along with 3cc-60mg Infinity™ cartridges and Clean Screen® hydrophobic cation exchange column for duplicates. Evaporation and reconstitution was necessary for detection using liquid chromatography-mass spectrometry (LC-MS). Results indicate that high recoveries reported in literature are often difficult to replicate. Recoveries averaged 5-50% for antidepressants using a variety of commercial SPE media. To better assess the factors that affect recovery, various parameters were studied including: solid phase chemistry, elution solvents, and wastewater composition. The largest challenge was identification of the proper elution conditions. Overall, higher recoveries are observed when using more specific analyte-solid phase interactions, however, elution steps need to be tailored to obtain optimal results.

Wastewater analysis: Challenges and optimization of solid phase extraction methods

253rd National Meeting (2017)

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