**3.1 Identification of contaminant proteins in hCG preparations**

All sample preparations were performed using standard procedures used in the Proteomics Core Facility of the Medical University of Vienna. No gel separations have been performed, and all results are generated upon the in-solution digest of different commercial formulations. Following chromatographic separation of tryptic peptides, the detection was performed using nanoelectrospray positive ionization and database search using the common SwissProt database.

For all analyzed samples, active substances were identified as major compounds. However, a number of other proteins were also identified in all samples. **Figure 1** shows an exemplary total ion chromatogram (TIC) of an hCG sample.

**Table 2** shows the total number of identified compounds in each of the analyzed sample in addition to the main sample component, and an overview of the proteins with the highest scores identified in all samples is shown in **Table 3**.
