Zanamivir (Za) is a highly polar and hydrophilic antiviral drug used for the treatment of influenza A
viruses. Za has been detected in rivers of Japan and it's environmental occurrence has the risk of inducing
antiviral resistant avian influenza viruses. In this study, a rapid automated online solid phase extraction
liquid chromatography method using bonded zwitterionic stationary phases and tandem mass spectrometry (SPE/LC–MS/MS) for trace analysis of Za was developed. Furthermore, an internal standard (IS)
calibration method capable of quantifying Za in Milli-Q, surface water, sewage effluent and sewage
influent was evaluated. Optimum pre-extraction sample composition was found to be 95/5 v/v acetonitrile/water sample and 1% formic acid. The developed method showed acceptable linearities
(r
2
Z0.994), filtration recovery (Z91%), and intra-day precisions (RSDr16%), and acceptable and
environmentally relevant LOQs (r20 ng L1
). Storage tests showed no significant losses of Za during 20
days and þ4/20 °C (r12%) with the exception of influent samples, which should be kept at 20 °C to
avoid significant Za losses. The applicability of the method was demonstrated in a study on phototransformation of Za in unfiltered and filtered surface water during 28 days of artificial UV irradiation
exposure. No significant (r12%) phototransformation was found in surface water after 28 days suggesting a relatively high photostability of Za and that Za should be of environmental concern.
& 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND