April 2008

Markes International Newsletter April 2008

Markes launches ClearView™ - GCMS reprocessing software for enhanced measurement of trace components

What is ClearView?

ClearView is GCMS reprocessing software for improving the analysis of trace compounds in complex real world samples. It uses a sophisticated Dynamic Background Compensation (DBC) algorithm to distinguish between chromatographic peaks and GC-background/baseline anomalies and eliminate the contribution of background ions from total ion chromatographic (TIC) data.

• Enhanced identification of target analytes and unknowns – especially at trace levels
• Reduced interferences, simpler integration and better run-to-run reproducibility.
• Enhanced sensitivity
• Cost reduction and enhanced lab throughput

ClearView operates on individual- or batches of stored data files from all leading brands of GCMS and creates additional, reprocessed data files. Reprocessing takes a few seconds per file and the original GCMS data files are left intact. The reprocessed data files can then be analysed using standard GCMS software e.g. for library searching.

ClearView: Improving spectral purity, compound identification and sensitivity

	TD-GCMS analysis of landfill gas, showing extreme column bleed. Original TIC data shown (black) together with ClearView reprocessed data (blue)
	Automatic analysis of the original GCMS data file does not correctly identify the trace component at 16.486 minutes because high level background ions interfere with the mass ion fragmentation (MIF) pattern
	Automatic analysis of the ClearView reprocessed data file shows greatly enhanced spectral purity allowing automatic identification of this trace component as thiophene. Sensitivity is also increased by a factor of ten

ClearView: Enhancing quantitative accuracy and repeatability

By minimising GCMS background ion contributions, ClearView provides a flatter baseline facilitating more accurate and repeatable automatic integration. Furthermore, it does this without compromising any of the mass ions contributing to the chromatographic peak.

Note that even if the same mass ion is present in both the peak and background signal, ClearView still accurately subtracts only the mass ion contribution due to the background.

Note also that the original data file is always retained. In cases where the ‘background’ eliminated by ClearView is not column bleed, but comprises a ‘hump’ of unresolved sample components (as shown below), the original data file is used for determining the total peak area – e.g. for simulated distillation or TVOC calculation - if required.

	TIC analysis of trace levels (3 pg on column) of octafluoronapthalene (OFN) in diesel using high speed chromatography and Time-of-Flight (TOF) MS. 5 minute run time. Original GCMS data (black) shown overlaid with ClearView reprocessed data (blue)
	Diesel data shown in extracted ion mode. Note identical peak area/height for OFN 272 signal indicating that peak-related information is not lost using ClearView
	3 overlaid repeat high speed GC-TOF MS analyses of OFN-spiked diesel, all reprocessed using ClearView. Full run (top), expanded area (bottom). Excellent integration (baseline assignment) and repeatability shown
	If the original data from this series of 3 analyses is overlaid (i.e. as above but without ClearView reprocessing) the reduction in integration accuracy (baseline assignment) and repeatability are clearly seen

ClearView: deskilling GCMS operation and boosting lab productivity

By reducing the need for time-consuming manual re-integration of complex total ion chromatograms by skilled GCMS technicians – e.g. for background subtraction - ClearView simultaneously improves data quality and lab productivity for minimal cost.

ClearView ™ is a trademark of ALMSCO International, UK.