Facilities - Plasma Ionization Multicollector Mass Spectrometry (PIMMS)
We have a ThermoFinnigan Neptune (PIMMS) with laser ablation facilities (New Wave Research UP213) for the measurement of isotope ratios in a range of elements. The PIMMS, UP213 and associated clean laboratory (designed and built by PicoTrace, GmbH) are recent additions to the MPI-EVA Archaeological Science Research Group’s existing stable isotope and dating facilities.
- The Neptune room of the PIMMS facility.
Currently, the PIMMS facility is setup for the analysis of isotope ratios of strontium from bones and teeth of modern and fossil hominines and fauna, which are used as proxy tools to decipher palaeodietary signatures and migratory behaviour. Future applications of these facilities may include the analysis of isotopes of uranium (dating), calcium (diet) and iron (diet) in modern and palaeoanthropological material.
The ThermoFisher Neptune is capable of obtaining high precision isotope ratios from a wide range of materials (biological or geological) either in solution form or directly with minimal sample preparation using the NewWave UP213 laser ablation system. The analysis of purified sampleusing the Elemental Scientific Inc. SSI quartz spray chamber and a variety of PFA MicroFlow (50-100 • L/min) nebulizers along with the Cetac ASX-110FR micro-autosampler.
The Neptune is integrated into the ‘clean room’ facility where it is housed in a custom-built climate controlled room. The Neptune features high sample throughput and three modes of resolution (low, medium and high) to help decrease the influence of polyatomic interferences. It is equipped with nine faraday collectors, four on either side of a center (axial) cup. The center faraday can be switched to function as an ion counting secondary electron multiplier (SEM) with a Retarding Potential Quadrupole lens (RPQ). Additionally, we have multiple ion counters that can used to measure isotope ratios in very small signals (<5mV).
Laser ablation of solid materials utilizes our NewWave Research UP231 Nd:YAG solid-state ultraviolet laser. The UP213 produces flat bottom ablation pits with spot diameters between 5 m m to 160 m m. Ablated sample material is swept into the plasma of the Neptune via a mixture of high purity helium, which passes through the ablation cell, and argon gases.
| The NewWave UP213 laser with power supply and water-cooling unit
Loading a sectioned sample into the helium flushed ablation cell.
Preparation of samples into purified element specific solutions for isotope analyses takes place in our metal-free, class 100 clean room located within the PIMMS facility. The entire facility, including the Neptune room, receives HEPA quality air. The sample preparation room is the cleanest room (with high positive air pressure) of the entire facility where we have six class 1000 workstations within which there are 10 computer programmable hotplates, double cascade Teflon sub-boiling cupola stills and a 16 well acid sample digestion system (DAS) all designed by PicoTrace GmbH.
In addition to the several general-purpose workstations (for sample drying and solution evaporation) there are two dedicated workstations for acid distillation and sample digestion. The hotplates are operated by two state-of-the-art software controlled touch screen interfaces located inside and outside the clean room.
Samples and standards are first weighed into Teflon beakers or Savillex vials in our adjoining balance room prior to digestion in high purity acids and then purified through Eichrom Technologies Inc. element specific chromatographic resins.
Recent visitors and ongoing users of the PIMMS facilities are:
Kate Britton (Associated Scientist MPI-EVA; University of Aberdeen)
Dr. Sandi Copeland (Associated Scientist MPI-EVA)
Dr. Vaughan Grimes (Associated Scientist MPI-EVA): Using isotope techniques (Sr, Pb and O) to trace hominin migration.
Dr. Yaowu Hu (MPI-EVA): Migration and the beginnings of agriculture in the Yellow River valley during the Chinese Neolithic.
Paul Sandberg (PhD student, University of Colorado at Boulder): An investigation of human migration in Medieval Nubia: strontium isotope analysis and the last Christian Nubians.
Dr. Colin Smith (MPI-EVA): Multi-isotope study of Minoan Create
Jennifer Stallo (Msc student, University of Cincinnati): Study of early Greek colonization at the site of Appolonia, Albania.