It should be noted the majority of studies detailed in table 1 have included a stability experiment, an element which can be missing from multinational studies . In these reports, all have claimed that analyte losses in sample storage and transport are negligible. However, it is critical to assess whether these stability experiments are fit for purpose. For Wilkinson et al. the stability study was conducted via spiking analytes into LC-MS water and monitoring at different temperatures; sampling at days two and seven. The freezing of environmental samples before shipping in this study was not included in the stability experiment. Hence, the freeze/thaw cycle, a potential route for analyte loss, was not accounted for. It has already been highlighted in the literature there can be a loss of certain compounds after freezing . Whilst it has been reported that there are compounds that are stable, such as carbamazepine and trimethoprim, others such as doxycycline and risperidone experience declining concentrations when frozen at -18 °C. Furthermore, this proposal by for international sampling is to cover multiple matrices (surface water, effluent and influent wastewater). The importance of undertaking a matrix-specific stability study is further highlighted by the fact that some compounds will have varying stability in the matrix in question. In the case for fluoroquinolones, enrofloxacin has shown to be still present after the freeze thaw cycle in an effluent wastewater sample, but absent in an influent wastewater sample .