FormNo. 203-821-260 02/05-REV0
LECO is a registered trademark of LECO Corporation
1
Separation Science Application Note
Pegasus
®
Characterizationof Ballpoint Pen Inks
by Solid-PhaseMicroextractionGas
Chromatography—Time-of-FlightMass
Spectrometry
Introduction
Time-of-Flight Mass Spectrometry (TOFMS) offers benefits for Gas Chromatography (GC) not
availablewith other mass spectrometers (e.g. quadrupoles andmagnetic sectors) because of its
fast acquisition rates (up to 500 spectra/second) and the spectral continuity associatedwith an
almost instantaneousmass analysis. Two of these benefits are automated Peak Find and Spectral
Deconvolution, algorithms that can be built into the data processing software.
Characterization of ink samples with GC-MS is important for several reasons, including formulation
determination for competitivemotives, quality assurance and control, counterfeit cases, and cases
where age of a document is in question. In this contribution, Solid-PhaseMicroextraction (SPME)
GC-TOFMS, with automated peak find and spectral deconvolution, is used to characterize ballpoint
pen inks. In addition, an automated Compare algorithm is employed to identify components
associatedwith aged ballpoint inks in a complex backgroundmatrix of volatile compounds
generated from the heating of paper to sample the aged ink by SPME.
Experiments
Two experiments were conducted for this work. The first involved characterization of black
(8 samples) and blue (5 samples) ballpoint inks for volatile organic compounds (VOCs) with SPME
GC-TOFMS. The secondwas determining VOCs remaining in ballpoint ink from aged scribbles on
paper.
Experimental Conditions
Solid-PhaseMicroextraction
A divinylbenzene/Carboxen/PDMS (50/30 µm) fiber from Supelcowas used. 5mm punched paper
holes with ink scribbles were placed into a 4mL vial that was cappedwith a PTFE-silicone septum
for SPME sampling. Five holes were used for the characterization experiment and eight were used
for the ink agingwork. The vial was sampled by headspace SPMEwhile either at 22°C
(characterization) or 70°C (aging). For the agingwork, the vial was equilibrated at 70°C for
10minutes prior to SPME. A 10minute SPME sampling timewas used to collect ink volatiles. The
fiber was desorbed into a 0.75mm injection sleeve (Supelco) in a split/splitless injector at 270°C
either at a 20:1 split ratio (characterization) or splitless with a valve time of 60 seconds (aging).
