Breath 2009, Germany: Abstracts

ALMSCO will be presenting two posters at the Breath 2009 conference in Germany

The abstracts for the two posters are:

A novel software package for identification of trace-level target compounds in clinical breath investigations using GC-MS

Lara Kelly , Nick Bukowski

The advantages of mass spectrometry (MS) in combination with gas chromatography (GC), in terms of providing both qualitative and quantitative information are well known. For investigation of trace-level species, such as in applications such as breath monitoring, the sampling and analysis incorporates some form of sample pre-concentration before analysis. However, even with this pre-concentration, reliable identification and accurate measurement of trace VOCs in breath at the lowest levels of interest may be compromised by chromatographic anomalies such as; column bleed, air /water interference and unresolved sample matrix components.

To address this issue, a novel software package has been developed and utilized for reprocessing stored GCMS data. It uses an innovative dynamic approach to distinguish and eliminate background interference (mass ions) as they change throughout a chromatographic run. Such dynamic background compensation (DBC) should be of tangible benefit to any GCMS work involving detection and measurement of trace target compounds in complex or uncharacterized samples, such as breath monitoring applications.

The DBC approach uses a sophisticated algorithm to minimize background ion contributions to the total ion chromatogram (TIC) conventionally produced by MS systems. These background ions can lead to incorrect compound identification, especially when the analytes of interest are at low concentrations and also difficulties in selecting peak integration points on an undulating baseline. By removal of these baseline anomalies, signal-to-noise ratios are increased leading to greater sensitivity which, combined with the greater spectral purity, leads to more accurate compound identification and quantitation.

Time-of-flight Mass Spectrometry – developments in technology and its suitability for breath monitoring applications

Lara Kelly, Nick Bukowski

Time-of-flight (TOF) mass spectrometry is one of the simplest yet most powerful approaches for MS identification of unknowns in a sample which, with recent advances in electronic technology and data processing, has come to be recognised as a valuable tool in trace-level analysis.

An important aspect of GCMS analysis is spectral acquisition rates, spectral purity and the relationship to sensitivity. The nature of the TOF approach means that, unlike traditional quadrupole technology, there is no loss of ion signal due to analyser mass filtering. This fundamental advantage yields dramatic sensitivity improvements in trace-level applications, such as breath monitoring. Consequently, with no requirement to perform selected ion monitoring (SIM) on target compounds, it becomes possible to maintain SIM-level sensitivity whilst still recording full spectral information throughout the analysis. For breath monitoring applications, this ensures no compromise in sensitivity for target species, and adds the latent capability for concurrent or subsequent detailed characterisation of unknown components within a sample. Another advantage of the TOF is its high spectral acquisition rate, rendering supreme quantitative precision and compatibility with emergent rapid-chromatographic techniques.

An overview of a novel TOF MS system will be presented, with discussion of the key features associated with the time-of-flight approach that enhance sensitivity and analytical speed for ambient air monitoring. Software algorithms within the TOF system enable on-line dynamic background compensation of data which significantly reduces noise and baseline anomalies, and examples will be shown to demonstrate this.