HESS - Technical note: Evaluation of a low-cost evaporation . From this aliquot, 1.5 mL was filled into a glass vial with screw cap (screw thread vials 1.5 mL, PP-screw thread caps with silicone/PTFE septum, WICOM Germany GmbH, Heppenheim, Germany) and stored at 4 ∘ C until isotope analysis.