Supplementary Derivatization of Methylglyoxal for LC-ESI-MS Analysis—Stability and Relative Sensitivity of Different Derivatives Stefan Fritzsche 1,2, Susan Billig 1,, Robby Rynek 1, Ramarao Abburi 1,3, Elena Tarakhovskaya 1,4, Olga Leuner 1,5, Andrej Frolov 6 and Claudia Birkemeyer 1,* 1 Institute of Analytical Chemistry, Faculty of Chemistry and Mineralogy, University of Leipzig, 04103 Leipzig, Germany;
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[email protected]; Tel.: +49-341-973-6092 Synthesis of the permanently charged hydrazines and anilines 1.1. Materials and chemicals Acetonitrile (ACN; ROTISOLV®, ≥ 99.8%, for preparative HPLC), formic acid (> 98%, p.s.), n-hexane (ROTISOLV®, ≥ 95%, GC Ultra Grade), potassium bromate (p.a.), zinc dust (98%), methanol (ROTISOLV®, ≥ 99.95%, LC-MS Grade) and diethyl ether (ROTIPURAN®, ≥ 99.5%, p.a.) were purchased from Carl Roth, Karlsruhe, Germany. Ethanol (absolute, > 99.7%, HiPerSolv® CHROMANORM®), cyclohexane, 4-hydroxyacetanilide (p.s., ≥ 99.0%), sodium hydrogen carbonate, sodium sulfite (purum, anhydrous), potassium carbonate and hydroxide, ammonia (35%, p.a.), acetic (100%, p.a.) and sulfuric acid (98%, p.a.) were purchased from VWR Chemicals, Darmstadt, Germany.