Background: Tons of pharmaceutical compounds are used every year around the world in
human and veterinary medicine, and these can reach wastewater treatment plants by metabolic excretion
and/or improper disposal. Some compounds are not completely eliminated during the wastewater purification
processes and are introduced into the environment through a variety of sources and pathways.
Pharmaceuticals can have large toxicological effects on the marine biota. It is necessary to develop sensitive
and selective analytical methodologies in order to determine these compounds at the low requiered
Methods: Development of procedures for the determination of four pharmaceuticals (acetylsalicylic acid,
naproxen, ibuprofen and gemfibrozil) in both water and sludge samples, based on solid phase extraction
(SPE) and microwave assisted extraction (MAE) followed by ultra-high performance liquid chromatography
with fluorescence detection (UHPLC-FD).
Results: The optimum conditions for the SPE procedure were extraction with an Oasis HLB cartridge, 250
mL of sample at pH 9 without salt addition, 5 mL of Milli-Q water for the wash step and 3 mL of methanol
for the elution. For the MAE procedure, the following conditions were used: power of 500 W, an extraction
time of 6 min and 5 mL of methanol as the extractant. Limits of detection between 13.20 and 1338 ng·L-1 for
liquid samples and between 1.16 and 86.4 ng·g-1 for solid samples were obtained. Recoveries were over 79%
and 69% for liquid and solid samples, respectively. The application of the optimized methodology to sewage
samples from different elimination treatments allows for the detection of gemfibrozil at a concentration of
2.52 µg·L-1. Sludge samples were also analyzed, but any compound was detected.
Conclusion: The optimized methods for the analysis of liquid and solid products from WWTPs were
satisfactorily validated for most of the target pharmaceutical compounds. Although the use of mass spectrometry
detection provides higher sensitivity and is suitable for the detection of the trace levels, optical
detectors continue to be very useful because of the low cost of their acquisition and maintenance.