**4. Conclusions**

The proposed methods, based on PMF by MALDI-TOF-MS as well as analysis with DICZE, provided an efficient procedure for the identification of peptides and proteins in illegally distributed samples. The use of trypsin as a proteolytic enzyme generated peptide fragments which covered 40 to 80% of the amino acid sequences of the analyzed proteins. The presence of a signature peptide in the peptide map facilitated the analyte identification considerably. MALDI-TOF-MS was also applied in the PSD mode for the amino acid sequencing of selected tryptic peptides as well as small peptides, such as ipamorelin.

The double-injection CE method provided complementary information on the native protein in the presence of a reference standard. This provided the possibility of performing a comparison between the electrophoretic patterns of the reference standard and the analyte to be identified. In addition, the double-injection based identifications were carried out by comparing the corrected migration time of the analyte and the observed migration time of the reference standard.

**43**

**Author details**

Ahmad Amini1

Martin Lavén1

and Anette Perolari1

\*, Torgny Rundlöf<sup>1</sup>

, Karin Björk3

\*Address all correspondence to: ahmad.amini@lakemedelsverket.se

1 Swedish Medical Products Agency, Dag Hammarskjölds väg, Uppsala, Sweden

2 Medical Mass Spectrometry Imaging, Department of Pharmaceutical Biosciences,

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

, Ezra Mulugeta1

3 Swedish Customs Laboratory, Solna, Sweden

provided the original work is properly cited.

Uppsala University, Uppsala, Sweden

, Henrik Lodén1,2, Johan A. Carlsson1

, Torbjörn Arvidsson1

,

, Iréne Agerkvist1

*Identification of Peptides and Proteins in Illegally Distributed Products by MALDI-TOF-MS*

*DOI: http://dx.doi.org/10.5772/intechopen.95335*

GH Growth hormone

ISD In source decay Nle Norleucine

PSD Post source decay SA Sinapinic acid TFA Trifluoroacetic acid

DSIP Delta sleep-inducing peptide

GHRP Growth hormone releasing peptide

hCG Human chorionic gonadotropin hGH Human growth hormone IGF-1 Insulin like growth factor 1

PMF Protein mass fingerprinting

DICZE Double-injection capillary electrophoresis

GHRH Growth hormone releasing hormone (somatoliberin)
