An assessment of different extraction and quantification methods of penta- and hexa-chlorobenzene from SRF fly-ash Dimitris E. Balampanis, Fr  ed  eric Coulon, Nigel Simms, Philip Longhurst, Simon J.T. Pollard, Cecilia Fenech, Raffaella Villa * Cranfield University, School of Energy, Environment and Agrifood, Cranfield MK43 0AL, UK article info Article history: Received 26 September 2016 Received in revised form 21 January 2017 Accepted 24 January 2017 Available online 26 January 2017 Keywords: Organic halogens Solvent extraction Energy from waste SRF MBT abstract Highly chlorinated benzenes, produced in the presence of organic matter and chlorine, are considered PCDD/Fs precursors, and are used as cost and time convenient substitute indicators for the indirect measurement of the latter. In this study penta- and hexa-chlorobenzene are quantified for the deter- mination of the organochloride load of fly ash from solid recovered fuel incineration. Some of the chlorobenzenes are formed under ‘de novo’ conditions, through heterogeneous (ash particles/flue gases) reactions and are therefore deeply incorporated within fly ash. Accelerated solvent extraction (ASE) and ultrasonic solvent extraction (USE), along with the equivalent clean-up methods suggested by literature were compared to traditional Soxhlet. The extraction efficiencies achieved were 83 ± 7.5% for Soxhlet, 111 ± 19% for PFE, and 67 ± 17% for ultrasonication. Soxhlet extraction and clean-up through a multilayer silica gel column gave more precise results compared to the other sample preparation methods. Furthermore, performance comparison of gas chromatography fitted with either a mass spectrometer operated in single ion monitoring mode (GC-MS-SIM), or electron capture detector (GC- ECD) highlighted that ECD can be used for measuring chlorobenzenes traces down to 0.21 ng g 1 , when the equivalent LOQ for MS-SIM was 3.26 ng g 1 . The results further suggest that ECD can provide better peak integration than MS-SIM in the detection of chlorobenzenes in fly ash extracts, due to the detector's sensitivity to halogenated compounds. © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction In response to the EU Landfill Directive diverting targets [1], the number of mechanicalbiological treatment (MBT) plants in Europe has nearly doubled in the last 8 years [2]. This growth has resulted in a significant increase of refuse derived fuel (RDF) and solid recovered fuel (SRF) being generated [3]. Notwithstanding the great potential for power generation of these materials, their market uptake is still relatively limited due to their fuel composi- tion reliability and in particular to their concentration of chlorine. The latter, in particular has potential negative impact on both the boiler and its emissions [4] and pivotal to its monitoring, is the extraction and quantification of its derivatives (such as poly- chlorinated dibenzo-p-dioxins and dibenzofurans) in gas and fly- ash. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) are persistent organic pollutants (POPs), which are highly toxic for humans. They are formed during thermal treatment processes mainly by de novo synthesis from chlorine and carbonaceous ma- terials and condensation reactions from precursors such as chlo- robenzenes (PCBz) and chlorophenols (PCP) [5e7]. Their quantification involves extensive sample preparation and technical skills-intensive analytical measurements [8]. Such quan- tification, although standardized, can present challenges even for specialised laboratories leading to high variations in the results, as shown from inter-laboratory comparison exercises [9]. Further- more, high costs for instrumentation such as, high resolution gas chromatograph coupled to high resolution mass spectrometer (HRGC/HRMS), and specialised consumables ( 13 C enriched com- pounds), along with time constraints due to the complexities of the extraction methods and the high number of isomers (210), make PCDD/Fs analysis quite demanding. Research for a time and cost effective substitute method for the indirect monitoring of PCDD/Fs in gaseous emissions, especially in waste incineration processes, started in the 1980s. Statistical * Corresponding author. E-mail address: r.villa@cranfield.ac.uk (R. Villa). Contents lists available at ScienceDirect Analytical Chemistry Research journal homepage: www.elsevier.com/locate/ancr http://dx.doi.org/10.1016/j.ancr.2017.01.003 2214-1812/© 2017 The Authors. Published byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Analytical Chemistry Research 12 (2017) 28e33