title: Understanding what we are measuring: standards and quantification of natural organic matter.
abstract: Some of the problems involved in quantifying operationally-defined parameters in natural waters are generally overlooked. In particular, the implications of the fact that standards have an effect on the results obtained that differs from usual analytical determinations are often ignored. On the basis of a revision of published data and personal experience, the case of natural organic matter types is discussed here for four different categories: carbohydrates, thiols, TEP (transparent exopolymers), and humic substances in freshwaters. In all cases, the results obtained are noticeably dependent on the standard, though the type of dependency varies. Key aspects are discussed in detail and advice is given about the procedure to follow when reporting data. Conclusions are applicable to other aquatic systems and natural organic matter fractions.
authors.affiliation: Institute F.-A. Forel, University of Geneva, 10 route de Suisse, CH-1290 Versoix, Switzerland; SCHEMA, Rue Principale 92, L-6990 Rameldange, Luxembourg. Electronic address: montserrat.filella@unige.ch.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Filella
mesh_terms: D001704:Biopolymers / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards*; D006812:Humic Substances / Q000032:analysis*; D012015:Reference Standards
chemical_list: D001704:Biopolymers; D006812:Humic Substances
keywords: Carbohydrates; Freshwaters; Humics; Natural organic matter; Quantification; Standards; TEP; Thiols