Mtp 384 ground steel maldi plate

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was performed using a matrix of 9 mg/ml 2,5-dihydroxybenzoic acid (DHB) (Sigma-Aldrich, P/N: 149357) dissolved in 0.2% trifluoroacetic acid (TFA). 2 μL of the DHB matrix was mixed with 2 μL assay supernatant and placed on a Bruker MTP 384 ground steel MALDI plate (Bruker Daltonics, Bremen, Germany P/N: 8280784) and dried under a stream of air prior to data collection. Experiments were performed on a Bruker Daltonics Autoflex system (Billerica, MA, U.S.A.). The data acquired over the range of m/z 0 to 3000 were collected in positive-ion mode by averaging 2000 laser shots using the lowest energy sufficient to obtain adequate signal-to-noise ratios.

High Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD) was performed on a Dionex ICS-5000 DC HPLC system operated by the Chromeleon software version 7 (Dionex) using a Dionex Carbopac PA200 column. Solvent A was double-distilled water, solvent B was 1 M sodium hydroxide (NaOH), and solvent C was 1 M sodium acetate (NaOAc). The gradient used was: 0–4 min, 10% solvent B and 2.5% solvent C; 4–24 min, 10% B and a linear gradient from 2.5 to 25% C; 24–24.1 min, 50% B and 50% C; 24.1–25 min, an exponential gradient of NaOH and NaOAc back to initial conditions; and 25–31 min, initial conditions.
Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) was performed on a Bruker Daltonics Autoflex System (Billerica, USA). The matrix, 2,5-dihydroxy benzoic acid, was dissolved in 50% methanol in water to a final concentration of 10 mg mL⁻¹. Oligosaccharide samples were mixed 1:1 (v/v) with the matrix solution. One microliter of this solution was placed on a Bruker MTP 384 ground steel MALDI plate and left to air dry for 2 h prior to analysis.