Comparison of manual filtration methods for on-site eDNA sample processing.
In this report, a systematic literature search was combined with a grey literature search to identify the most promising manual filtration methods for the processing of water samples by citizen scientists. The top three methods were subsequently trialled by nine volunteers to assess the manual difficulty of each method and to determine the volume of water filtered. Three manual filtration methods were identified: (a) Filtration using a syringe attached to a 0.45 um sterivex filter; (b) Filtration using a syringe attached to a 0.45 um sterivex filter assisted by a silicone gun; and (c) Filtration using a syringe attached to a Sylphium cartridge. Nine volunteers trialled the three methods using water samples with three turbidity levels (12 Formazine Turbidity Unit (FTU), 29 FTU and 59 FTU). The results identified method (b) 'Filtration using a syringe attached to a 0.45 um sterivex filter assisted by a silicone gun' as having the lowest scores for physical difficulty and pain, whilst also filtering comparable water volumes to the other trialled methods. DNA concentrations and quality were comparable across the three trialled methods.