Page 240 - Advances in Forensic Applications of Mass Spectrometry - Jehuda Yinon

1522_book.fm Page 213 Thursday, November 13, 2003 9:58 AM

Chromatogram Plots
File: I:\data0999\15704 ms2.ms
Sample: 10.0 MIN SAMPLING TIME, 5 MINDESORB, GB 16/9/99 10:37 AM
Sample Notes: RN0391-01, 99-0817-F #1, STAIR TREADS - GC/MS/MS - GB
Operator: D.SUTHERLAND Scan Range: 1-1034 Time Range: 0.02 - 15.00 min.
Slecl 1 7.099 m In. Scan: 343 Chan: 1 Ion: NARIC: 12512
B P 131 (3894-100%) 15704 ms2.ms 131
100%
75% 119
50%
105
25% 91 147
57 75 84 165 181 194 202
0%
Slecl 2 7.962 m In. Scan: 385 Chan: 1 Ion: NARIC: 10774
100% B P 131 (3932-100%) 15704 ms2.ms 131
75%
50%
105
25% 84 91 119 146
50 57 66 174 185 193
0%
D Iff Slecl 1 Specl 2 7.099 m In. Scan: 343 Chan: 1 Ion: MARIC: 12512
100% Normalized 7.962 m In. Scan: 385 Chan: 1 Ion: MARIC: 10774
50%
0%
−50%
−100%
50 75 100 125 150 175 200 m/z
kCounts 15704 ms 2.ms Ions: 131 all
3
2
1
Counts 15704 ms 2.ms Ions: 146 all
700
600
500
400
300
200
100
6 7 8 9 minutes
2 3
289 338 387 433 Scans
Figure 5.17 Comparison of GC/MS/MS spectra for other indane isomers: ion
ratios different.
The instrumental conditions in a target class analysis are more general
and not compound specific. The following conditions in Table 5.3 are pre-
sented as an example only and should be regarded as a minimum number
of precursor and product ions that may be chosen to define the organic
chemical classes that make up the majority of ignitable liquids. Energy iso-
lation windows, etc. may be different, depending on the instrument. MS/MS
is different in that the spectra and the class ion profile will be different from
instrument to instrument, as the energies programmed will result in some
difference in profiles. The important aspect is that the MS/MS acquisition
parameters should be identical for both sample and reference material anal-
ysis. Thus, sample-to-reference data comparisons originating on the same
instrument will be excellent. Precursor and product ion class profiles may be
different from one instrument to another due to different product ion effi-
ciencies and energies.

5.2.4.1 GC/MS/MS — Chemical Analysis — Examples
We have utilized GC/MS/MS as a second confirmation analysis for samples
that were weak, complex, or highly weathered in the GC/MS analysis for
over 6 years. This two-analysis approach has been in response to the fact

© 2004 by CRC Press LLC