FormNo. 203-821-260 02/05-REV0
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8
The Compare procedure starts with automated peak find, spectral deconvolution, library searching
of the Peak Table, and calculating peak area/height for each compound (for the Reference sample).
For the paper used here, over 200 compounds were located and library searched in less than
2minutes!When Compare is used against the sample (ink scribbles), a Peak Table containing four
analyte types is generated.
−
Match (compound found andwithin user-defined concentration range)
−
Out of Tolerance (compound found but outside user-defined concentration range)
−
Contaminant (compound not in Reference)
−
Not Found (compound not in sample, versus Reference)
A Peak Table can be filtered such that any or all of the analyte types is displayed in the table.
In the present case, the Contaminants, which can be defined as ink compounds, are of highest
interest. Table 3 shows the Contaminants (ink compounds) illuminated through the use of Compare
that had spectra in the NIST library. Another five compounds were located, but their spectrawere
not in the library, and are therefore not included in the table. The Compare data processing time,
which included automated peak find, spectral deconvolution, calculation of area/height, matching
of results, and library searching of unmatched compounds, took less than aminute.
Table3.
Ink compounds (Contaminants fromCompare) in an aged ink scribble.
Retention time (sec.) CompoundName
175.4
2-Butoxyethanol
192.0
Benzaldehyde
195.5
Phenol
201.6
2-(2-Ethoxyethoxy)-ethanol
205.5
2-Ethoxyethanol
219.4
Phenylethanol
258.4
2-Phenoxyethanol
264.3
Phenoxypropanol
342.1
Diphenylamine
Figure 8 graphically illustrates the Compare results by overlaying chromatograms for the paper and
the paper/ink scribble samples. Diphenylamine, markedwith a blue asterisk, is one ballpoint ink
compound locatedwith Compare. Although it may be possible to visually locatemajor compounds
of interest through inspecting overlaid total ion chromatograms (TICs), the automatedway is
faster, and often leads to location of important compounds that may be buried beneath the TIC.
