IBA-DAPNe: a new system for sub-micron scale molecular speciation and quantification

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Our vision is to develop a unique resource for molecular imaging and profiling that will be truly internationally leading. Molecular imaging is widely used for the characterisation of materials, and there are numerous methods available for generating and liberating ions from a surface and hence generating a chemical concentration map including those using mass spectrometry (MS). Since 2004, there has been an explosion of new MS methods in which a sample is analysed under ambient conditions. This has enabled the high throughput analysis of samples that are not vacuum compatible and has significantly speeded up the sample handling, which is often the time-limiting factor of vacuum-based techniques. Quantification, chemical speciation and spatial resolution are three key drivers for a multitude of applications, and there is currently not a single technique that can provide all these attributes at the sub-micron scale.Direct Analyte Probed Nano Extraction Mass Spectrometry (DAPNe-MS) is a method of selecting and removing a small quantity of material from a surface, using a capillary tip attached to a nanomanipulator. The extracted material is then introduced into a mass spectrometer via nanoelectrospray ionisation. The technique has achieved sensitivity at the attogram level and is particularly suited to picking up trace materials from surfaces. Unlike imaging mass spectrometry techniques, the process of sample removal and ionisation are decoupled and there is minimal fragmentation. This provides better selectivity and opportunities for superior quantification compared with other ambient MS methods. Due to its recent inception, no DAPNe facility exists in the UK. Surrey houses in its Ion Beam Centre (IBC) the only ambient pressure imaging MeV-Secondary Ion Mass Spectrometry (SIMS) system in the world which offers sub-micron molecular imaging (EP/I036516/1). SIMS, an Ion Beam Analysis (IBA) technique, is known for its excellent spatial resolution but a drawback is the fragmentation that occurs during the sputtering process. Currently available techniques at Surrey and NPL have imaging capability with high spatial resolution, can distinguish between molecular species and even provide molecular concentration maps. Techniques which provide trace element information at the ppb level in ambient conditions (Particle Induced X-ray Emission - PIXE, also an IBA technique) are also readily available. The missing component is trace molecular information, which DAPNe will provide. We will use current techniques to highlight specific regions which require a more detailed analysis with very high sensitivity using this new unique probe. Complementary use of IBA and DAPNe (IBA-DAPNe) is unique internationally and would provide unprecedented level of characterisation of samples at the sub-micron scale in full ambient conditions. The proposed IBA-DAPNe system will provide missing information for researchers from any discipline and research projects will be prioritised on the basis of scientific excellence. Access will be provided free of charge for the first two years. We see particular benefits for those working across 6 key EPSRC themes: Energy, Manufacturing for the Future, Healthcare Technologies, Global Uncertainties, ICT and Engineering.