Mercury speciation by high-performance liquid chromatography atomic fluorescence spectrometry using an integrated microwave/UV interface. Optimization of a single step procedure for the simultaneous photo-oxidation of mercury species and photo-generation of Hg 0 ☆ Daiane P.C. de Quadros b , Beatrice Campanella a , Massimo Onor a , Emilia Bramanti a , Daniel L.G. Borges b , Alessandro D'Ulivo a, ⁎ a National Research Council of Italy, C.N.R., Instituto di Chimica dei Composti Organo Metallici – ICCOM – UOS Pisa, Area della Ricerca, Via G. Moruzzi 1, 56124 Pisa, Italy b Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC, Brazil abstract article info Article history: Received 11 July 2014 Accepted 17 September 2014 Available online 28 September 2014 Keywords: Photochemical vapor generation Mercury Microwave photochemical reactor Speciation High performance liquid chromatography We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography–atomic fluorescence spectrometry (HPLC–AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg 2+ to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composi- tion of HPLC mobile phase and catalytic action of TiO 2 nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μgL -1 for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation–atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Mercury cycle in the environment is a result of natural and human activities. Mercury emissions from human activities move by weather and wildlife throughout the environment, and natural processes can convert mercury into organic methylmercury. This organomercuric species is disposed to biomagnification, the sequence of processes in an ecosystem by which higher concentrations of a particular chemical are reached in organisms higher up the food chain through a series of prey–predator relationships. The gastrointestinal tract readily absorbs ingested methylmercury, and it is mostly found complexed with free cysteine and with proteins and peptides containing that amino acid. The methylmercuric–cysteinyl complex is recognized by amino acid transporting proteins in the body as methionine, another essential amino acid and, because of this mimicry, it is transported freely across the blood–brain barrier and the placenta [1]. Therefore, the development of sensitive and specific methods for the speciation of mercury is of great importance for environmental and biological studies. Numerous methods based on high performance liquid chromatogra- phy (HPLC) on-line hyphenation with element-specific detection methods, such as inductively coupled plasma mass spectrometry (ICP- MS), anodic stripping voltammetry (ASV) and atomic spectrometry, have been developed for the speciation of mercury in recent years. Several reviews summarize the recent progress in this field [2–5]. Among the cited detection techniques, atomic fluorescence spectrometry (AFS) is one of the most sensitive, selective and low-cost methods for the determination of mercury [5]. As with other instrumen- tal methods of analysis, sample introduction remains an important issue in AFS because the sensitivity and limits of detection (LODs) are depen- dent on the sampling efficiency. Vapor/hydride generation is a widely adopted sample introduction method for atomic spectroscopy, yielding the advantages of efficient matrix separation, high analyte transport efficiency, high selectivity, simple instrumentation and ease of automa- tion. Vapor generation using tetrahydroborate (THB) is considered to be the most widespread and successful one for the determination of trace and ultra trace amounts of elements belonging to groups IV–VI and mercury [6]. Spectrochimica Acta Part B 101 (2014) 312–319 ☆ Selected papers presented at European Symposium on Atomic Spectrometry ESAS 2014, Prague, Czech Republic, March 16 - 21, 2014. ⁎ Corresponding author. Tel.: +39 050 3152293; fax: +39 050 315 2555. E-mail address: dulivo@pi.iccom.cnr.it (A. D'Ulivo). http://dx.doi.org/10.1016/j.sab.2014.09.019 0584-8547/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Spectrochimica Acta Part B journal homepage: www.elsevier.com/locate/sab