Study on complexation of palladium with thiourea-based ligands and its determination in simulated high-level liquid waste using solid phase extraction-electrospray mass spectrometry Vijay M. Telmore 1,2 • Pranaw Kumar 1 • P. G. Jaison 1 Received: 2 July 2018 / Published online: 5 September 2018 Ó Akade ´miai Kiado ´, Budapest, Hungary 2018 Abstract ESI–MS was used to investigate the complexation of Pd(II) with thiourea based ligands such as thiourea (TU), N- benzoylthiourea (BTU), N,N-diethyl N 0 -benzoylthiourea (DEBT) in gas phase. Experimental parameters like quadrupole ion energy and collision energy were optimized for acquiring the spectra of Pd complexes with TU, BTU, and DEBT. Tandem mass spectrometric (ms/ms) studies were carried out to investigate the relative stability of various Pd species in the gas phase. Studies showed that DEBT forms a predominately ML 2 type complex and hence is a better chelating agent for ESI–MS determination of Pd compared to TU and BTU. Based on these studies, an automated solid phase extraction method was developed for separation of Pd using DEBT, followed by its determination using ESI–MS. Developed method was used for determination of Pd in simulated high level liquid waste. Keywords Palladium  Electrospray ionization mass spectrometry  Thiourea  N-benzoylthiourea  N,N-diethyl N 0 -benzoylthiourea Introduction Significant quantities of platinum group of elements (PGEs) viz. ruthenium (Ru), rhodium (Rh) and palladium (Pd) are formed in nuclear reactors as fission products [1, 2]. Their limited availability and increasing global demand make nuclear reactor produced PGEs as an alter- native potential source of PGEs for selective applications. Extraction of these elements from nuclear waste is also important for better nuclear waste management as they form separate phase during the vitrification process [3]. High level liquid waste (HLLW) obtained from repro- cessing of spent nuclear fuel of PHWR (burn up 6700 MWD per te) and FBTR (burn up 150 GWD per te) con- tains * 132 ng mL -1 and * 390 ng mL -1 of Pd, respectively. Palladium obtained from fission comprises of isotopes 104 Pd (17 wt%), 105 Pd (29 wt%), 106 Pd (21 wt%), 107 Pd (17 wt%), 108 Pd (12 wt%), 110 Pd (4 wt%). Among all isotopes, 107 Pd is the only radioactive isotope with a half life of 6.5 9 10 6 years and is a soft ß emitter with ßmax of 35 keV. Still it finds various applications in nuclear field as the associated radioactivity of 107 Pd may be insignificant [2]. Several research groups are exploring the possibility of recovering Pd from high level liquid waste by methods like solvent extraction [4] and ion exchange [5]. Pd recovered from nuclear waste is proposed to use in the purification and storage of tritium [6], coating of zircaloy cladding materials [7] and nuclear fusion systems [8]. Thiourea (TU) and its derivatives offer selective binding with PGEs due to their soft nature and hence find applications in extraction and separation of these elements from different matrices [9, 10]. TU is a strong Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10967-018-6165-x) contains supplementary material, which is available to authorized users. & Vijay M. Telmore telmorev@barc.gov.in & P. G. Jaison jaipg@barc.gov.in 1 Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India 2 Homi Bhabha National Institute, TSH Complex, Anushakti Nagar, Mumbai 400 094, India 123 Journal of Radioanalytical and Nuclear Chemistry (2018) 318:1249–1259 https://doi.org/10.1007/s10967-018-6165-x