Research

Research in our group revolves around analytical chemistry with a special focus on direct surface analysis, elemental analysis, speciation, plasma sciences, and instrumentation.

We use techniques such as Ambient Desorption/Ionization Mass Spectrometry (ADI-MS), Inductively Coupled Plasma – Mass Spectrometry (ICP-MS), Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES), and Pulsed Radio-frequency Glow Discharge – Optical Emission Spectrometry (rfGD-OES).

Research Highlight I:

Surface Analysis

Direct surface analysis of solid and liquid samples can be performed by ambient desorption/ionization mass spectrometry (ADI-MS) with little to no sample pretreatment and low limits of detection. Since the inception of the technology a few years ago, a variety of plasma-based desorption/ionization sources have been published, but little has been reported on the fundamental processes and reaction mechanisms responsible for analyte ionization. In a collaboration with George C.-Y. Chan, Jacob T. Shelley, Gary M. Hieftje (Indiana University), Joshua S. Wiley, Ayanna Jackson, and R. Graham Cooks (Purdue University) fundamental studies on the low-temperature plasma probe (LTP) have been performed. In addition, we are currently coupling LTP to a high-resolution mass spectrometer for direct analysis of various types of samples.

Related publications:
A. Albert, C. Engelhard, Anal. Chem., 2012, published online (DOI: 10.1021/ac302287x).
G. Chan et al., Anal. Chem., 2011, 83 (10), 3675–3686.
G. Chan et al., J. Anal. At. Spectrom., 2011, 26(7), 1434-1444.


Research Highlight II:

Nanoparticles

Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool for ultra trace analysis. In this project, ICP-MS is used for the characterization of silver and gold nanoparticles. Conventional and single-particle detection mode as well as various sample introduction strategies are optimized for highly sensitive nanoparticle detection.

Related publications:
B. Franze, I. Strenge, C. Engelhard, J. Anal. At. Spectrom., 2012, 27(7), 1074-1083 (DOI: 10.1039/C2JA00003B).

C. Engelhard, Anal. Bioanal. Chem., 2011, 399(1), 213-219.
C. Engelhard et al., J. Anal. At. Spectrom., 2008, 23 (3), 407-411.

100-nm Silver Nanoparticles (B. Franze, S. Krüger)

Research Highlight III:

Elemental Imaging and Speciation Analysis with a Large-format Pulsed Glow Discharge

In a collaborative effort with Prof. Gary M. Hieftje, Dr. Steven J. Ray (Indiana University), Dr. Volker Hoffmannn, Dr. Maxim Voronov (IFW Dresden), and Dr. Wolfgang Buscher, Unversity of Münster, we are currently involved in the development of new instrumentation for elemental imaging and speciation analysis.  In this project it was demonstrated that a pulsed rf-glow discharge coupled to a monochromatic imaging spectrometer can provide spatially resolved elemental information – i.e. detect and quantitate proteins on gels after gel electrophoretic separations. Currently, a large-format glow discharge prototype instrument is being optimized for the analysis of large-format samples.

This project is funded by the German Research Foundation (DFG) and the National Science Foundation (NSF).

Related publications:

M. Voronov et al., J. Anal. At. Spectrom., 2012, 27, 419-425 (DOI: 10.1039/c2ja10325g).
M. Voronov et al., J. Anal. At. Spectrom., 2011, 26(4), 811-815.
C. Engelhard et al., J. Anal. At. Spectrom., 2010, 25(12), 1874-1881.