Analysis of acidic, basic and neutral pharmaceuticals in river waters: clean-up by 1°, 2° amino anion exchange and enrichment using an hydrophilic adsorbent

Abstract

A fast and sensitive LC-MS/MS method suitable to monitor a set of 24 pharmaceuticals belonging to 9 therapeutical families was developed using an analytical column of reduced dimensions and an appropriate SPE procedure for acidic, basic and neutral analytes. Furthermore, a preliminary assessment of the occurrence and levels of these substances in surface waters of the Leça and Douro rivers, located in the north of Portugal, was conducted. Among 17 different SPE adsorbents tested, some of them often neglected, the JTBaker H₂Ophilic provided the best recoveries (average 86%). When compared to the amino and quaternary ammonium adsorbents, the 1°, 2° amino proved the most suitable clean-up media for surface water samples prior to enrichment by SPE. The overall method provided limits of detection generally below 5 ng L⁻¹ and a precision below or around 10% RSD in three non-consecutive days at 500 ng L⁻¹ and around 12% at 50 ng L⁻¹ concentration levels. The confirmatory capabilities of the method developed are especially welcome either through the MS³ spectra or the isotopic pattern.

The first known results regarding the occurrence of pharmaceuticals in Leça river confirmed its expected high contamination load and the successful selection of the target pharmaceuticals. Concentrations up to 770 ng L⁻¹ of bezafibrate, 925 ng L⁻¹ of paracetamol, 389 ng L⁻¹ of hydrochlorothiazide and 283 ng L⁻¹ of furosemide were measured. The most ubiquitous in both seasons, February and June 2009, were bisoprolol, furosemide, bezafibrate and gemfibrozil. In Douro river the abundance and contamination level of pharmaceuticals was much lower which gives a clear indication that the hydraulic features of the river provide enough attenuation of the several contamination sources whereas Leça is highly impacted by insufficiently treated anthropogenic effluents.

Keywords:

• pharmaceuticals
• surface water
• LC-MS/MS
• hydrophilic SPE
• anion exchange clean-up
• Leça and Douro rivers

Acknowledgements

The authors would like to thank IAREN - Water Institute of the Northern Region for technical and financial support. Portuguese Foundation for Science and Technology (FCT) is greatly acknowledged for the post-doc grant SFRH/BPD/39650/2007 and PhD grant SFRH/BD/44509/2008. The authors are indebt to Macherey-Nagel, Biotage, JT Baker, Phenomenex and Restek for kindly supplying samples of the SPE cartridges. This work was carried out under the project NORTE-01-0162-FEDER-000023 co-funded by ON.2 O Novo Norte.