Page 29 - Application Notebook - Solution for Food Safety

Application No. C154
News

„ Spectrum based identification
To increase the confidence in reporting results the Fig. 7 highlights the advantage of using a library
number of qualifier transitions was increased for each searchable fragment ion spectrum in identifying and
pesticide and the combined MRM transitions were quantifying desmedipham and phenmedipham. Both
used to create a product ion spectrum. This MRM desmedipham and phenmedipham share several
product ion spectrum can then be automatically common fragment ions and have similar retention
compared against a reference spectrum to generate a times. Using MRM Spectrum Mode and comparing to a
product ion spectrum match score using conventional library searchable spectra, both desmedipham and
library matching. phenmedipham are positively identified (fragment
ions at m/z 154 and 182 are absent in product ion
spectrum for phenmedipham).

Desmedipham
6 MRM’s; RT 10.801 mins
1:318.00>136.10 CE: -27.0
2:318.00>301.00 CE: -9.0 Desmedipham
3:318.00>182.00 CE: -14.0 182 Acquired spectrum
4:318.00>154.10 CE: -23.0
5:318.00>108.10 CE: -40.0 136
6:318.00>93.10 CE: -48.0 301

93 154
108
0
93 108 Desmedipham
154 Library Spectrum
Match score 99
301
136
182
10.50 10.60 10.70 10.80 10.90 11.00 11.10 11.20 11.30 100.0 125.0 150.0 175.0 200.0 225.0 250.0 275.0 m/z
min

Phenmedipham
6 MRM’s; RT 11.041 mins
1: 318.00>136.10 CE: -27.0
2:318.00>301.00 CE: -9.0 Phenmedipham
3:318.00>182.00 CE: -14.0 136 Acquired spectrum
4:318.00>154.10 CE: -23.0 No fragment ions present at
5:318.00>108.10 CE: -40.0 m/z 154 and 182 301
6:318.00>93.10 CE: -48.0
93
108
0
93 108
Desmedipham
154 Library Spectrum
No hit reported
301
136
182
10.50 10.60 10.70 10.80 10.90 11.00 11.10 11.20 11.30 100.0 125.0 150.0 175.0 200.0 225.0 250.0 275.0 m/z
min

MRM chromatogram for desmedipham and phenmedipham spiked into a cumin extract at 0.1 mg/kg. As phenmedipham shares
common transitions and elutes at a similar retention time as desmedipham the MRM spectrum can be used to distinguish between both
pesticides to avoid false positive reporting.