People in the Department
 

Dr Barry L Sharp

Senior Lecturer in Analytical Chemistry
BSc, DIC, PhD London, CSci, FRSC
Telephone: ++44 (0)1509 222572
FAX: ++44 (0)1509 223925
Email: B.L.Sharp@lboro.ac.uk

 

Barry Sharp leads the Atomic Spectrometry Research Group which is part of the Centre for Analytical Science. The group interest is focused on inductively-coupled plasma and laser source mass spectrometry (ICP-MS) and encompasses a wide range of activities from studies on the fundamentals of instrument design to the development of new techniques for the detection and quantification of bio-molecules.

Research Interests

Bio-Analysis
Work is on-going on the use of ICP-MS, both high resolution MS (Thermo Element II XR) and collision-reaction cell MS (Thermo PQ ExCell), to improve the sensitivity and quantitation of some important bio-assays. For example, we have used site specific labeling of oligonucleotides to tag them with nano-gold particles thereby enhancing the sensitivity of detection by in excess of 700 compared with analysis using 31P.1 Collaborating with colleagues from the Cancer Prevention and Bio-markers group at Leicester University assays have been developed to determine the degree of adduct formation when cells are exposed to Pt-based drugs such as cis and oxaliplatin. The interactions of these drugs with nucleobases is being studied using ES-MSn techniques. Work is on-going in relation to the detection and quantification of low abundance phospho-peptides and proteins using separation techniques coupled to ICP-MS.

A current project with Dr Tamer Shoeib (Research Fellow) involves determining the structure and energetics of non-covalent metal-peptide interactions using the Gaussian molecular modelling package on the EPSRC-NSCCS facility. The theoretical study is used to elucidate experimental MSn data obtained using our linear ion trap electrospray MS (Thermo LTQ). This study provides underpinning information about the interactions of metals with bio-molecules which is a central theme of the research of the group.

Collaboration with colleagues in the Department of Human Sciences involves the development of a method for the determination of phytoestrogens in saliva using LC-MS/MS.

Optical detection of ions by ICP-MS-CLS
A recent paper2 described a feasibility study of the use of laser coincidence spectroscopy (CLS) for the detection of ions in ICP-MS. This concept employs highly specific laser excited ionic fluorescence in time correlation with non-specific ion detection to remove background interferences, isobars and to improve the abundance sensitivity of the ICP-MS. The technique, named ICP-MS-CLS, is well suited to rare isotopes and is a potential competitor for high performance MS techniques such as AMS and RIMS. As part of this work a modeling study has been carried out on the use of a 3D ion trap for cooling ions prior to downstream optical spectroscopy.

Laser Ablation LA-ICP-MS
Laser ablation is a powerful tool for direct solid sampling, but accurate quantification is hindered by the difficulty of preparing calibration standards. Under sponsorship from the VAM programme, 3 calibration strategies have been investigated. The first uses the so called on-line additions technique to enable the use of aqueous standards for calibration and this work has recently been published.3 For powdered samples, a technique named “Matrix Assisted Laser Ablation” MALA has been developed that uses a chromophore as the sample binder to enable the use of non-matrix matched powdered samples as standards.4 Current work involves adapting the isotope dilution technique to work in conjunction with these methods. Another area of activity is the development of LA for biological analyses involving work on LA cell design and the direct sampling of biological tissues. The group has an on-going general interest in sample introduction systems for ICP-MS.5

Collision/Reaction Cells
Holistic analysis of ICP-MS spectra modified by the use of H2, He and mixtures thereof in a hexapole collision cell has enabled the identification of the major chemistries affecting cell performance.6  More recently, the influence of input ion kinetic energy (IKEE) on cell reactivity has been demonstrated7 and it has been shown that this can be used to compliment kinetic energy discrimination (KED) in improving cell selectivity. Current applications of collision reaction cells includes work on I8, P and S.

Isotope Ratio Measurements
The measurement of isotope ratios is important with respect to isotope dilution analysis, stable isotope tracer studies, nuclear accounting and geochronology. The group has worked previously on improving the precision of such measurements, but more recently particular attention has been given to characterizing the mass bias affect9 that is the limiting factor in many isotope ratio determinations.

 

I am a Member of the Editorial Board of the Journal of Analytical Atomic Spectrometry (JAAS - impact factor 4.03) published by the Royal Society of Chemistry, www.rsc.org/jaas. If you would like to publish an article in JAAS, please e-mail or call me and I will be happy to discuss this with you.

 

Selected publications:

  1. Nano-particle labelling of nucleic acids for enhanced detection by inductively-coupled plasma mass spectrometry (ICP-MS), S. L. Kerr and B. L. Sharp,  Chemical Communications, 2007, 43, 4537-4539.
  2. Coincidence laser spectroscopy for the detection of ions in ICP-MS (ICP-MS-CLS). A feasibility study, B. L. Sharp,  P. S. Goodall, L. M. Ignjatovic and H. Teng, J. Anal. At. Spectrom., 2007, 22, 1447-1470.
  3. On-line additions of aqueous standards for calibration of laser ablation inductively coupled plasma mass spectrometry: theory and comparison of wet and dry plasma conditions, C. O’ Connor, B. L. Sharp and P. Evans, J. Anal. At. Spectrom., 2006, 21, 556-565.
  4. Absorption coefficient modified pressed powders for calibration of laser ablation inductively coupled plasma mass spectrometry,      C. O’Connor, M.R. Landon  and B.L. Sharp, J. Anal. At. Spectrom., 2007, 22, 273 – 282.
  5. An application of computational fluid dynamics (CFD) to the characterisation and optimisation of a cyclonic spray chamber for ICP-AES and ICP-MS, G Schaldach, H Berndt and B L Sharp, J. Anal. At. Spectrom, 2003, 18, 742-750.
  6. The use of background ions and a multivariate approach to characterise and optimise the dominant H2-based chemistries in a hexapole collision cell used in ICP-MS, C P Ingle, P K Appelblad, M A Dexter, H J Reid and B L Sharp, J. Anal. At. Spectrom., 2001, 16, 1076-1084.
  7. The effects of ion energy on reactivity and species selectivity in hexapole collision/reaction cell ICP-MS, M A Dexter, H J Reid and B L Sharp, J. Anal. At. Spectrom., 2002, 17, 676-681.
  8. Determination of iodine and molybdenum in milk by quadrupole ICP-MS, H. J. Reid, A. A. Bashammakh, P. S. Goodall, M. R. Landon C. O’Connor, and B. L. Sharp, Talanta, DOI 10.1016/J.Talanta.2007.10.051
  9. Instrument response functions, mass bias and matrix effects in isotope ratio measurements and semi-quantitative analysis by single and multi-collector ICP-MS, C P Ingle, B L Sharp, M S A Horstwood, R R Parrish and D J Lewis, J. Anal. At. Spectrom., 2003, 18, 219-229.

Extended list of publications
 
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