IRMS & ICPMS

ICP-MS (Inductively Coupled Plasma Mass Spectrometry)


Lab manager
Prof Fabio Marzaioli

 

General Overview of the methodology

 

Multi-Collector High-Resolution Inductively-Coupled Plasma Mass Spectrometry (MC-HR-ICP-MS) provides the opportunity to measure the isotopic ratio of a great variety of elements. An MC-ICP-MS is generally composed of the following parts:
• an ICP source (preparation) producing positive ions with sensible efficiencies (≥ 40%) for elements with ionization energies up to 10 eV
• an electrostatic and magnetic sector (analysis) with Double focusing Geometry (Nier Johnson) resulting in an accurate separation of masses
• an array (Multicollector setup) of ion detectors (detection), usually Faraday Cups or Secondary Electron Multipliers

 

 

Laboratory equipment

Testo e immagini seguenti a comparsa/scomparsa (clikkando sul titolo o sull'immagine)

The CIRCE ICP-MS laboratory accommodates a Neptune Plus ThermoFisher MC-ICP-MS, a versatile instruments which is suitable for measurements of isotopic ratios of a wide range of elements. The Neptune Plus MC-ICP-MS is composed of the following parts:
• A plasma interface, held at ground potential, containing a nebulizer, spray chamber and torch (the plasma)
• A 90° ElectroStatic Analyser (ESA)
• A 90° magnetic analyser
• A 9 Faraday cups's adjustable array
• Secondary Electron Multipliers (SEM)
Before being injected into the ICP ion source, a sample is generally purified (e.g. ion exchange or extraction chromatography), dissolved in HNO3 and nebulised through a pumping system. The ICP ion source extracts positive ions which are then accelerated at 10 kV. The Neptune Plus can be operated at three different resolution settings (low, medium and high) by actuating source and detector slits which cut the beam to select the isotopes of interest and reject molecular interferences. In case of low beam intensities, SEM can replace faraday cups to provide higher sensitivity.

 

 

Main applications carried out at the ICP-MS lab

 

Environmental pollution - Hydrology

 

Studies of source apportionment of NO3- in contaminated acquifer can be supported by measurements of the isotopic composition of Boron (11B). Boron (B) co-migrates with NO3- from the sewage system because Sodium Perborate (NaBO3) is used as an oxidation bleaching agent in domestic and industrial cleaning products. Since 11B values of sewage are easily distinguished from uncontaminated groundwater, the 11B is useful to identify NO3- sources. At the CIRCE ICP-MS lab, measurements of 11B have helped the apportionment of NO3- contamination sources in shallow groundwater in five regions of the Po River basin.

 

Environmental pollution - Nuclear safeguards

 

 

Nuclear plants are a possible source of radionuclide into the enviroment. Uranium (238, 235 and 234) and Plutonium (239 and 240) isotope ratio can be utilized to trace environmental releases from nuclear plants. The ICP-LAB at CIRCE has been involved in measurements of those nuclides in soil, water and sediment samples from the Garigliano river, where the decomissioning phase of a nuclear plant is underway.
Titolo e immagine qui di seguito visibili e clikkabili

 

Cosmogeochemistry

Elements isotope fingerprint represents a powerful technique for examining the origins of meteorites in the Solar System. It is, for example, possible to correlate differentiated and primitive meteorite types, and study mixing processes in the early solar nebula. Nichel (Ni) is a moderately refractory and siderophile element, and also a major component of both iron and silicate meteorites. 60Ni isotope variations can therefore potentially be used to date nebula events. Similarly, 60Fe is believed to be synthesised in a high temperature stellar environment, not within the Solar System. The presence of “live” 60Fe inferred from Ni isotope compositions represents a diagnostic fingerprint of materials created in a nearby stellar explosion that was subsequently transported to the nascent solar nebula. At the ICP-MS lab, measurements of 60Ni in pallasites (a class of stony–iron meteorite) have helped infer their origin.
Titolo e immagine qui di seguito visibili e clikkabili

 

Archaeometry

Measurements of radiogenic Lead (208, 207, 206) and Strontium (87) isotope ratios can be utilised to reconstruct the origin of metals and organics in ancient manufacts and bones. Strontium (Sr) builds up in the bones and tooth enamel as food is digested. In contrast to the bones, Sr is no longer exchanged in tooth enamel after the age of four, allowing researchers to tell where the person lived as a child. Different isotope ratios in the bones and teeth are therefore proof of migration after the age of four. At the ICP-MS lab of CIRCE, such measurements have been used to provide important informations about commercial networks and migration pathways in ancient times.
Titolo e immagine qui di seguito visibili e clikkabili

 

Food traceability

Radiogenic Strontium (87) is the long-lived radiogenic daughter of ⁸⁷Rb and can be utilized to determine the provenance of animal and vegetal foods. The ⁸⁷Sr/⁸⁶Sr ratio of any geological material (i.e. minerals and rocks) on Earth depends on its time integrated ⁸⁷Rb/⁸⁶Sr ratio, and thus it is related to three main parameters: (1) the initial radiogenic isotopic abundance, (2) the age of the rock/mineral, and (3) the parent/daughter isotope ratio. The ⁸⁷Sr/⁸⁶Sr ratio is not modified during the uptake of the plant and it is transferred unchanged to all living beings of the food chain, thus remaining identical to that of the substratum from which the original plant or vegetable grew. At the ICP-MS lab at CIRCE, measurements of ⁸⁷Sr/⁸⁶Sr have provided information about about the area of provennance of different Italian wines and olive oils.

Accesso Utenti

Gli Utenti registrati possono accede a contenuti riservati. Se non hai le credenziali consulta la pagina dei contatti per richiederle.