Analytica Chimica Acta 759 (2013) 8–20 Contents lists available at SciVerse ScienceDirect Analytica Chimica Acta jou rn al hom epa ge: www.elsevier.com/locate/aca Characterisation of hydrogen bond perturbations in aqueous systems using aquaphotomics and multivariate curve resolution-alternating least squares  A.A. Gowen a,b,∗ , J.M. Amigo b,c , R. Tsenkova b a School of Biosystems Engineering, University College Dublin, Dublin, Ireland b Biomeasurement Technology Laboratory, Kobe University, Kobe, Japan c Department of Food Sciences, Quality and Technology, University of Copenhagen, Frederiksberg, Denmark h i g h l i g h t s ◮ Multivariate curve resolution (MCR) applied to water spectra at different temperatures and salt content. ◮ Three distinct components with varying temperature dependence were present in water perturbed by temperature. ◮ Locations of their MCR pure com- ponents of salt solutions varied according to the ionic strength of the salt used. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 11 July 2012 Received in revised form 19 September 2012 Accepted 3 October 2012 Available online 12 October 2012 Keywords: Water Near infrared Hydrogen bond Multivariate curve resolution Aquaphotomics a b s t r a c t Aquaphotomics is a new discipline that provides a framework for understanding changes in the structure of water caused by various perturbations, such as variations in temperature or the addition of solutes, using near infrared spectroscopy (NIRS). One of the main purposes of aquaphotomics is to identify water bands as main coordinates of future absorbance patterns to be used as biomarkers. These bands appear as consequence of perturbations in the NIR spectra. Curve resolution techniques may help to resolve and find new water bands or confirm already known bands. The aim of this study is to investigate the appli- cation of multivariate curve resolution-alternating least squares (MCR-ALS) to characterise the effects of various perturbations on the NIR spectra of water in terms of hydrogen bonding. For this purpose, the perturbations created by temperature change and the addition of four solutions of different ionic strength and Lewis acidity were studied (NaCl, KCl, MgCl 2 and AlCl 3 , with concentrations ranging from 0.2 to 1 mol L -1 in steps of 0.2 mol L -1 ). Transmission spectra of all salt solutions and pure water were obtained at temperatures ranging from 28 to 45 ◦ C. We have found that three distinct components with varying temperature dependence are present in water perturbed by temperature. The salt solutions stud- ied exhibited similar trends with respect to the temperature perturbation, while the peak locations of their MCR-ALS pure components varied according to the ionic strength of the salt used. © 2012 Elsevier B.V. All rights reserved.  Paper presented at the XIII Conference on Chemometrics in Analytical Chemistry (CAC 2012), Budapest, Hungary, 25–29 June 2012. ∗ Corresponding author. Tel.: +353 17167413. E-mail address: aoife.gowen@ucd.ie (A.A. Gowen). 0003-2670/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aca.2012.10.007