Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)
ESI New Wave NWR193 laser ablation system coupled to an Agilent 7500cs ICP-MS
Technique: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)
Analyses obtained for: most elements in the mass range 5-250 atomic mass units (practically 7Li to 238U)
Typical detection limits: in the order of a few parts per billion (ppb) to a few parts per million (ppm)
Spatial resolution: 1 to 150 microns
The Museum’s dedicated laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) system is capable of low-level trace element determinations in most solid materials, with minimal sample destruction and spatial resolutions of 1-150 microns. Precise uranium-lead (U-Pb) age determinations can be obtained in zircons and other accessory mineral phases.
The instrument used for analysis is an ESI New Wave NWR193 Laser Ablation system coupled to an Agilent 7500cs Inductively Coupled Plasma Mass Spectrometer.
How it works
- a laser beam is focused and fired at the surface of a sample held in a chamber
- the energy of the laser beam is transferred to the sample and causes material to be removed (ablated).
- the material removed is picked up in a flow of gas passing through the sample chamber and transported to an inductively coupled plasma mass spectrometer (ICP-MS)
- as the material passes through the inductively coupled plasma it is ionised
- the ions are separated in the mass spectrometer according to their mass-to-charge ratio and then counted on a detector
To fully quantify data the concentration of an internal standard must be known prior to laser analysis. The purpose of the internal standard is to correct for the differing physical properties and ablation characteristics of samples and reference materials. Typically the concentration of a major element as determined by electron probe microanalysis (EPMA) is used as an internal standard.
Preparation of samples
Samples do not need surface preparation, but data quality is improved considerably if the samples are polished.
Samples should be clean, dry and where possible any carbon coating from previous electron probe microanalysis should be removed.
Any gold coating on samples previously imaged by scanning electron microscopy or ion probe analysis must be removed thoroughly. Residues of gold coating can severely affect LA-ICP-MS data quality.
Samples that need to be prepared (cut, mounted and polished) should be presented to the preparation laboratory at least four weeks prior to the LA-ICP-MS booking.
Sample sizes that can be accommodated
Prepared materials: these are normally presented in the form of 25mm diameter polished blocks or polished thin/thick sections of 48mm x 26mm (typical probe size). Tissue section sizes and 25mm circular sections can also be accommodated. Odd section and block sizes may also be accommodated. Please contact for further information
Unprepared samples: oddly sized and shaped samples may be accommodated up to the size of the sample chamber (100mm x 100mm x 20mm). Please contact for further information.
Dr Teresa Jeffries, Head of Chemistry
Submitting a sample
Most inorganic solid materials are suitable for LA-ICP-MS, and are routinely analysed at the Museum including:
- minerals (including age determination of accessory minerals)
Although less routine, the following may also be analysed by LA-ICP-MS at the Museum:
- metals, including meteorites and sulphide minerals
- organic (keratin) tissues such as feathers, horn, beaks, hair
- plants and wood
While it is possible to analyse soft (wet) body tissues with LA-ICP-MS the Museum does not specialise in this area.