title: Separation and measurement of Pa, Th, and U isotopes in marine sediments by microwave-assisted digestion and multiple collector inductively coupled plasma mass spectrometry.
abstract: This manuscript describes a new protocol for determination of Pa/Th/U in marine sediments. It is based on microwave-assisted digestion and represents an important reduction of working time over conventional hot-plate digestion methods, and the use of HClO(4) is avoided. Although Th and U are completely dissolved with a first microwave step, around 40% of (231)Pa remains undissolved, and a short hot-plate step with reverse aqua regia is required to achieve total digestion and spike equilibration. Next, the method involves a separation of these elements and a further purification of the Pa fraction using Dowex AG1-X8 resin. Separation with Bio-Rad and Sigma-Aldrich resins was compared; although both perform similarly for Th and U, Pa yields are higher with Bio-Rad. Finally, samples are measured using a Nu instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS). Overall chemical yields range around 50% for Pa, 60% for Th, and 70% for U.
authors.affiliation: Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain. cesar@negre.us
authors.forename: César
authors.initials: C
authors.lastname: Negre
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Thomas
authors.forename: José Luis
authors.initials: JL
authors.lastname: Mas
authors.forename: Jordi
authors.initials: J
authors.lastname: Garcia-Orellana
authors.forename: Gideon M
authors.initials: GM
authors.lastname: Henderson
authors.forename: Pere
authors.initials: P
authors.lastname: Masqué
authors.forename: Rainer
authors.initials: R
authors.lastname: Zahn