Iron 2 sulfate heptahydrate

Cylindrospermopsin standard (purity > 95%) was purchased from Eurofins/Abraxis (Eurofins/Abraxis, Warminster, PA, USA). Methanol (99.9% HPLC grade), Ferrozine (97%), and peroxidase from horseradish (type II) were obtained from Sigma-Aldrich (Sigma-Aldrich, São Paulo, SP, Brazil). Acetic acid glacial (99.7% HPLC grade) was purchased from J.T Baker (J. T. Baker, Brazil). Hydroxylamine hydrochloride (96%) and ammonium hydroxide (27% v/v) were purchased from Synth (Synth, Diadema, SP, Brazil). Ammonium acetate (97%), N,N-Diethyl-p-phenylenediamine sulfate salt (98%), sodium phosphate dibasic (98%), sodium phosphate monobasic (98%), and hydrogen peroxide (35% v/v) were obtained from Neon (Neon, Suzano, SP, Brazil). Sodium sulfite (98%), sulfuric acid (98% v/v), hydrochloric acid (36.5% v/v), iron (II) sulfate heptahydrate (99%) and iron (III) chloride hexahydrate (97%) were purchased from Dinâmica (Dinâmica, Indaiatuba, SP, Brazil).
All solutions used in the experiments were prepared using ultrapure water (Milli-Q Reference water purification system, C79625, Merck Millipore, Darmstadt, Hesse, Germany).

High-Performance Liquid Chromatography (HPLC) grade chloroform, methanol and formic acid were obtained from Tedia Brazil^® (RJ, Brazil). Folin-Ciocalteu, ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), TPTZ (2,4,6-tripyridyl-s-Triazine) and nitric acid were obtained from Sigma-Aldrich (St. Louis, MO, USA). Acetic acid, chloride acid, ferric chloride heptahydrate, iron (II) sulfate heptahydrate, and aluminum chloride hexahydrate were obtained from Dinâmica^® (Sao Paulo, Brazil).