Quantification of refractory organic substances in freshwaters: further insight into the response of the voltammetric method
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A recently published method for quantifying refractory organic matter (often referred to as humic substances) in freshwaters was applied to a wide range of International Humic Substance Society (IHSS) humic compounds in order to (i) gain a better understanding of the mechanism of the voltammetric response which is the basis of the analytical method and (ii) provide guidance on choosing the optimal standard to be used. At the same time, the sensitivity of the technique has been increased by switching from the pulse mode initially proposed to the square-wave mode. The results obtained show that (i) differences in adsorption onto the electrode rather than differences in complexation strength are responsible for the differences in the intensity of the signal obtained for the different humic compounds, (ii) carboxylate, N- and S-containing groups do not play a role in the voltammetric signal.
KeywordsHumics Fulvics Refractory organic matter IHSS SWV Mo(VI) Freshwaters
We would like to thank Thomas Meinelt (Leibniz-Institut of Freshwater Ecology and Inland Fisheries, Berlin, Germany) for the gift of HS1500.
- 1.Filella M (2008) Environ Chem Lett. doi: 10.1007/s10311-008-0158-x
- 7.McKnight DM, Andrews ED, Spulding SA, Aiken GR (1994) Limnol Oceanogr 39:1972–1979Google Scholar
- 9.Volk CJ, Volk CB, Kaplan LA (1997) Limnol Oceanogr 42:39–44Google Scholar
- 14.Filella M, Chanudet V, Quentel F (2008) Freshwaters: do ‘humics’ always represent 50% of NOM? In: Perminova IV, Kulikova NA (eds) Proceedings of the 14th International Meeting of the International Humic Substances Society, September 14–19, 2008, Moscow–Saint Petersburg, Russia, Humus Sapiens, Moscow, 2008, pp 151–154Google Scholar
- 15.Aiken GR (1985) Geochemistry and isolation. In: Aiken GR, McKnight DM, Wershaw RL, MacCarthy P (eds) Humic substances in soil, sediment and water. Wiley-Interscience, New YorkGoogle Scholar
- 18.Swift RS (1996) In: Sparks DL (ed) Methods of soil analysis. Part 3. Chemical methods. Soil Science Society America, American Society of Agronomy, Madison, pp 1011–1069Google Scholar
- 20.Kolthoff IM, Lingane JJ (1952) Polarography, vol 1. Interscience, New YorkGoogle Scholar