title: Degradation of artificial sweeteners via direct and indirect photochemical reactions.
abstract: We studied the direct and indirect photochemical reactivity of artificial sweeteners acesulfame, saccharin, cyclamic acid and sucralose in environm entally relevant dilute aqueous solutions. Aqueous solutions of sweeteners were irradiated with simulated solar radiation (>290 nm; 96 and 168 h) or ultraviolet radiation (UVR; up to 24 h) for assessing photochemical reactions in surface waters or in water treatment, respectively. The sweeteners were dissolved in deionised water for examination of direct photochemical reactions. Direct photochemical reactions degraded all sweeteners under UVR but only acesulfame under simulated solar radiation. Acesulfame was degraded over three orders of magnitude faster than the other sweeteners. For examining indirect photochemical reactions, the sweeteners were dissolved in surface waters with indigenous dissolved organic matter or irradiated with aqueous solutions of nitrate (1 mg N/L) and ferric iron (2.8 mg Fe/L) introduced as sensitizers. Iron enhanced the photodegradation rates but nitrate and dissolved organic matter did not. UVR transformed acesulfame into at least three products: iso-acesulfame, hydroxylated acesulfame and hydroxypropanyl sulfate. Photolytic half-life was one year for acesulfame and more than several years for the other sweeteners in surface waters under solar radiation. Our study shows that the photochemical reactivity of commonly used artificial sweeteners is variable: acesulfame may be sensitive to photodegradation in surface waters, while saccharin, cyclamic acid and sucralose degrade very slowly even under the energetic UVR commonly used in water treatment.
authors.affiliation: Finnish Environment Institute (SYKE), Laboratory Centre, Hakuninmaantie 6, FI-00430, Helsinki, Finland. noora.perkola@environment.fi.
authors.forename: Noora
authors.initials: N
authors.lastname: Perkola
authors.affiliation: Department of Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.|Sito Oy, Tuulikuja 2, FI-02100, Espoo, Finland.
authors.forename: Sanna
authors.initials: S
authors.lastname: Vaalgamaa
authors.affiliation: Department of Environmental Sciences, University of Helsinki, Niemenkatu 73, FI-15140, Lahti, Finland.|Ordior Oy, Konalantie 47 A, FI-00390, Helsinki, Finland.
authors.forename: Joonas
authors.initials: J
authors.lastname: Jernberg
authors.affiliation: Department of Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.|Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35 (Survontie 9), FI-40014, Jyväskylä, Finland.
authors.forename: Anssi V
authors.initials: AV
authors.lastname: Vähätalo
mesh_terms: D003494:Cyclamates / Q000737:chemistry / Q000528:radiation effects; D006207:Half-Life; D010782:Photolysis; D012439:Saccharin / Q000737:chemistry / Q000528:radiation effects; D013395:Sucrose / Q000031:analogs & derivatives / Q000737:chemistry / Q000528:radiation effects; D013549:Sweetening Agents / Q000737:chemistry / Q000528:radiation effects*; D013843:Thiazines / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects*; D018508:Water Purification
chemical_list: D003494:Cyclamates; D013549:Sweetening Agents; D013843:Thiazines; D014874:Water Pollutants, Chemical; D013395:Sucrose; C026285:trichlorosucrose; D012439:Saccharin; C006362:acetosulfame
keywords: Acesulfame; Artificial sweeteners; Photochemical reactions; Photolytic half-life; Solar simulation; Sucralose