Acetone

All reagents used were of highest purity, iodoform (CHI 3 ), 1,2 dibromopropane (used as internal standard SI) and THMs mixture 100 µg/µL of each compound: chloroform (CHCl 3 ), bromodicloromethane (CHBrCl 2 ), dibromochloromethane (CHBr 2 Cl), and bromoform (CHBr 3 ), were purchased from Sigma-Aldrich (Steinhein Germany). Iodo-trihalomethanes (I-THMs): bromodiiodomethane (CHBrI 2 90%), bromochloroiodomethane (CHBrClI 95%), chlorodiiodomethane (CHClI 2 95%), dibromoiodomethane (CHBr 2 I 95%) and dichloroiodomethane (CHCl 2 I 95%) were purchased from Orchid Cellmark (New Westminster, BC, Canada). Methanol, n-hexane, toluene, acetonitrile and acetone were purchased from Teknokroma (Barcelona, Spain). n-Octanol was supplied from Merck (Barcelona, Spain). Accurel Q 3/2 polypropylene hollow fiber membranes with an inner diameter of 600 µm, 200 µm of wall thickness and 0.2 µm pore size was obtained from Wuppertal (Germany). Ultrapure water (18MΩ cm) was obtained from a Milli-Q water-purification system (Millipore, Watford, UK) and was used for spiked samples and blanks preparation. to achieve a final concentration of 5 µg L -1 .

All the chemical compounds used for the BG-11 medium, sodium chloride, ammonium acetate (98%) and tetrabutylammonium acetate were supplied by Sigma-Aldrich Chemical Co. (Madrid, Spain). Acetone and diethyl ether (analysis grade) were supplied by Teknokroma (Barcelona, Spain). N,N-dimethylformamide (DMF) and hexane (analysis grade) and methanol, methyl tertbutyl ether and water (HPLC grade) were supplied by Panreac (Barcelona, Spain). The deionised water used was obtained from a Milli-Q 50 system (Millipore Corp., Milford, MA, USA). Solutions of carotenoid standards -carotene, -cryptoxanthin and -cryptoxanthin esters, echinenone, myxoxanthophyll, neoxanthin and violaxanthin isolated from natural sources were obtained following the procedures described by Britton, Liaaen-Jensen and Pfander (1995) , while zeaxanthin and -carotene standards were obtained from Extrasynthese (Genay Cedex, France). Aliquots of the carotenoid standard solutions were analysed with the same experimental conditions and the UVvisible and bbCID MS n spectra were acquired and compared with those obtained from the microalgae extracts, so that direct experimental criteria were applied for identification of known carotenoids. Standards of zeinoxanthin and -cryptoxanthin epoxides were not available, so that identification was performed according to literature data.