Journal of Chromatography B, 910 (2012) 138–148 Contents lists available at SciVerse ScienceDirect Journal of Chromatography B jo u r n al hom epage: www.elsevier.com/locate/chromb Study of the photodegradation of 2-bromophenol under UV and sunlight by spectroscopic, chromatographic and chemometric techniques  Anusha Jayaraman a , Sílvia Mas a,b,∗ , Romà Tauler b , Anna de Juan a a Chemometrics Group, Department of Analytical Chemistry, Universitat de Barcelona, Av. Diagonal, 647, 08028 Barcelona, Catalonia, Spain b Environmental Chemometrics Group, Department of Environmental Chemistry, Institute of Environmental Assessment and Water Diagnostic (IDAEA-CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia, Spain a r t i c l e i n f o Article history: Received 10 January 2012 Accepted 23 March 2012 Available online 2 April 2012 Keywords: Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) Hybrid soft- and hard-modeling-Multivariate Curve Resolution (HS-MCR) Photodegradation process Process analysis a b s t r a c t This work is focused on the study of the photodegradation of 2-bromophenol under the action of UV light and sunlight. The photodegradation process has been monitored using UV–Vis spectroscopy and High Performance Liquid Chromatography coupled to diode array and mass spectrometry detectors in tandem (HPLC–DAD–MS). Multivariate resolution methods, such as Multivariate Curve Resolution- Alternating Least Squares (MCR-ALS) and hybrid soft- and hard-modeling-Multivariate Curve Resolution (HS-MCR), have been applied to the experimental data to obtain the information about the kinetic evolu- tion and identification of the compounds involved in the photodegradation process. From the analysis of HPLC–DAD results, the complexity of the photodegradation process has been confirmed. Ten components were found to be involved in parallel, second- or higher-order reactions, which could not be ascertained from the spectroscopic results. The HPLC–MS results allowed postulating the identity of some of the com- pounds (such as hydroxyderivatives and bromophenol homologs) which resulted from the reactions of photohydrolysis, debromination and bromine transfer to different position of the phenol ring. The effect of the UV light and sunlight on the photodegradation process was found to affect mainly the rate of the reaction, but not the identity of the photoproducts formed. The advantages and limitations of the spectro- scopic and chromatographic analysis were also discussed. The potential of combining spectroscopic and chromatographic data in a single multiset structure was also shown. This strategy, uses the advantage of the good definition of the process time axis from the spectroscopic experiment and the capability to distinguish among compounds, linked to the use of chromatographic information. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Brominated flame retardants (BFR’s) have been used since long and are persistently found in the environment, where they cause contamination and biohazard effect [1]. 2-Bromophenol is a small compound that can be formed by the thermal degradation of some flame retardants [2]. 2-Bromophenol undertakes hazardous reac- tions with acyl chlorides, acid anhydrides and oxidizing agents. It is used as a precursor to resorcinol and could be released to envi- ronment through waste streams. Furthermore, it has been found to cause skin, eye, mucous membranes and upper respiratory tract irritations, with varying effects depending on the duration and intensity of chemical exposure [3]. Due to these implications and  “This paper belongs to the Special Issue Chemometrics in Chromatography, Edited by Pedro Araujo and Bjørn Grung”. ∗ Corresponding author at: Chemometrics Group, Department of Analytical Chemistry, Universitat de Barcelona, Av. Diagonal, 647, 08028 Barcelona, Catalonia, Spain. Tel.: +34 93 403 44 45; fax: +34 93 402 12 33. E-mail address: silviamas@ub.edu (S. Mas). the limited information about their fate in the environment, it is needed to study the chemical photodegradation of this compound. As an environmental pollutant, 2-bromophenol is exposed to different natural radiation sources and, therefore, it is relevant to know the pathway and products derived from the photoinduced processes. Upon exposure to UV light or sunlight, the bromophenols in aquatic environment undergo photochemical changes. Prelimi- narily, we could expect that the UV light induced an increase in the rate of reactions with respect to the sunlight due to the shorter wavelength and higher energy of the UV radiation. However, there is no knowledge on how these different radiation sources could affect the identity of the photoproducts formed. There have been studies on the decomposition of monochlorophenols by UV irradia- tion [4] and under sunlight [5,6], and a study on the flash photolysis of monobromophenols [7], but a description of the kinetic path- ways of bromophenols is not clear yet. Since the lowly brominated compounds were seen to undergo degradation phenomena under the action of UV light [8], a deeper study of the photodegradation of these compounds under different illuminating sources has a clear environmental relevance. 1570-0232/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jchromb.2012.03.038