1. Supplement material to Ref. JASMS Ms. No. 2012-5464 Detection of an amine impurity and quality assessment related to this impurity of the UV MALDI matrix  -cyano-4-hydroxy- cinnamic acid for the analysis of peptides in the attomole range Justyna Rechthaler, Ernst Pittenauer, Tanner M. Schaub and Günter Allmaier

2. Legends to Figures in the Supplement Figure 1S Positive-ion MALDI mass spectra (curved field reflectron mode) of two CHCA matrix batches: matrix B (a) and matrix E (b). Matrix solvent: acetone. The mass spectrum (a) exhibits a [M+H] + /[M*+H] + ratio > 1, which represents a high quality matrix, and the following spectrum (b) a [M+H] + /[M*+H] + ratio < 1 representing a matrix of lower quality. Figure 2S Comparison of the [M+H] + /[M*+H] + (a) and [2M+H] + /[M*+H] + (b) ratios of five various CHCA matrix batches (A, B, C, D and E, matrix solvent: acetone) obtained on a bench-top (MALDI IV) and floor-standing high resolution TOF instrument (AXIMA-CFR). Figure 3S Positive-ion MALDI FT-ICR mass spectrum of the matrix E (including highest amount of the contaminant) with the region around m/z 102. The spectrum was internally calibrated with following matrix signals: [M-CO 2 +H] +, [M-H 2 O+H] + and [M+H] +. The RMS error on the three point calibration was -1.22 ppm. The mass spectrometric resolving power observed for the m/z 102.1276 signal was 230000 (FWHM). Figure 4S Positive-ion MALDI high energy (E Lab 2 keV) CID (LinTOF/RTOF) mass spectrum of the precursor ion m/z 102.2 (derived from matrix E in acetone).

3. 0 10 20 30 40 50 60 70 80 90 100 %Int. 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Mass/Charge 190 172 102 212 280 379 [M-H 2 O+H] + [M+H] + [M+Na] + [M*+H] + [M-CO 2 +Na] + [2M+H] + 168 Fig. 1S a

4. 0 10 20 30 40 50 60 70 80 90 100 %Int. 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Mass/Charge 102 [M*+H] + [M-CO 2 +Na] + [M+H] + [M+Na] + [2M+H] + 190 212 172 379 Fig. 1S b

5. Fig. 2S a

6. Fig. 2S b

7. 102.1 102.4102.2102.3 12 C 6 H 16 N 1 observed at m/z: 102.1276 Theoretical mass at m/z: 102.12772 Error: –1.2ppm 102.1276 m/z [M*+H] + Fig. 3S

8. m/z 20 100 Intensity 600 0 44.11 58.14 59.14 72.16 73.17 74.18 102.20 60.16 30 60 50 40 90 8070 Precursor ion C 6 H 16 N [M*+H] + H H Fig. 4S