High-performance liquid chromatography - mass spectrometry analysis of the parent drugs and their metabolites in extracts from cress (Lepidium sativum) grown hydroponically in water containing four non-steroidal anti-inflammatory drugs

- Cress has been grown hydroponically in water contaminated (spiked) with four NSAIDs.
- 20 drug related compounds including several substances not yet described in this context were detected in plant extracts.
- Combining the information from multiple HPLC-MS platforms allowed the detection of the selected analytes at trace levels.
- The final method allows detecting the parent drug and its major metabolites in concentrations typical for reclaimed water.

In this paper the metabolism of four non-steroidal anti-inflammatory drugs, (ketoprofen, mefenamic acid, naproxen, and diclofenac) by cress (Lepidium sativum) is described. Cress was cultivated hydroponically in water spiked with the parent drugs at levels ranging from 0.01 mg L−1 to 1 mg L−1. Employing an approach based on the analysis of the plant extracts by HPLC coupled either with quadrupole-time-of-flight mass spectrometry, or Orbitrap MS or triple quadrupole (QqQ) MS allowed the identification of twenty substances (sixteen metabolites and four parent drugs). Metabolites were formed from the parent drug by hydroxylation or conjugation with polar molecules such as glucose, small organic acids or amino acids. Introducing a pre-concentration step employing solid-phase extraction and using HPLC-QqQ/MS in the multiple reaction monitoring mode enabled the positive detection of 11 of the proposed metabolites next to the four parent components even in plants grown in a 0.01 mg L−1 solution of the tested drugs, which is close to the conditions in real reclaimed waters.