Multiresidue analysis of bat guano using GC-MS/MS

Bats are the second largest mammalian order and are an endangered species group with a strong need for contamination monitoring. To facilitate non-invasive monitoring of the ecological burden in bat populations, a multiresidue method for the simultaneous quantification of 119 analytes including pesticides, persistent organic pollutants (POPs), active pharmaceutical ingredients (APIs), polycyclic aromatic hydrocarbons (PAHs), UV blockers, plasticizers, and other emerging pollutants in bat guano with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed. Sample preparation and clean-up were performed with a modified QuEChERS approach based on DIN EN 15662. The method uses 1.00 g bat guano as sample with acetonitrile and water for liquid-liquid extraction. Phase separation is assisted by citrate-buffered salting out agent. For clean-up of the extract, primary secondary amine (PSA) was combined with graphitized carbon black (GCB). The lower limits of quantification (LLOQ) ranged between 2.5 and 250 µg kg^-1. Linearity was shown in a concentration range from the respective LLOQs to 1250 µg kg^-1. The median of the mean recovery was 102.4%. Precision was tested at three concentrations. Method and injection precision were adequate with a relative standard deviation (RSD) below 20%. Furthermore, the comparative analysis with LC-MS/MS demonstrated the reliability of the results and provided a valuable extension of the analytical scope. As proof of concept, three guano samples from a German nursery roost of Myotis myotis were analysed. The results show a time-dependent change in contaminant concentration, highlighting the strong need for non-invasive contamination monitoring of whole bat populations.