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  • Synthesis and application of ionic liquid matrices (ILMs) for effective pathogenic bacteria analysis in matrix assisted laser desorption/ionization (MALDI-MS).

Synthesis and application of ionic liquid matrices (ILMs) for effective pathogenic bacteria analysis in matrix assisted laser desorption/ionization (MALDI-MS).

Analytica chimica acta (2013-03-05)
Hani Nasser Abdelhamid, Judy Gopal, Hui-Fen Wu
ABSTRACT

Application of two new series of ionic liquid matrices (ILMs) based on the two most predominantly used conventional organic matrices (Sinapinic acid and 2,5-DHB) in conjugation with various bases (aniline (ANI), dimethyl aniline (DMANI), diethylamine (DEA), dicyclohexylamine (DCHA), pyridine (Pyr), 2-picoline(2-P), 3-picoline(3-P)) for bacterial analysis in matrix assisted laser desorption/ionisation mass spectrometry (MALDI-MS) are reported. The results reveal that ionic liquid matrices could significantly enhance the protein signals, reduce spot-to-spot variation and increase spot homogeneity. More importantly, these novel matrices would not produce any interference during MALDI-MS analysis. Among these ILMs, 2,5-DHB/ANI, 2,5-DHB/DMANI and 2,5-DHB/Pyr can be successfully applied to intact bacterial studies compared with other ILMs. Base molecules when added to conventional matrix can promote proton transfer between the bacterial lysate and the matrices. Due to the enhanced proton transfer efficiency by the ionic liquid matrices, almost all the biomolecules of the intact bacterial cells can be ionized and detected in the MALDI-MS. All synthesized ILMs were characterized using ESI (+)/MS and UV-spectroscopy.

MATERIALS
Product Number
Brand
Product Description

Supelco
Sinapic acid, matrix substance for MALDI-MS, ≥99.5%, Ultra pure
Sigma-Aldrich
Dicyclohexylamine nitrite, 97%
Sigma-Aldrich
Aniline-4-13C, 99 atom % 13C
Sigma-Aldrich
Diethylamine hydrochloride, ReagentPlus®, 99%
Supelco
Pyridine solution, certified reference material, 2000 μg/mL in methanol
Sigma-Aldrich
Pyridine hydrochloride, purum, ≥98.0% (AT)
Supelco
Aniline, analytical standard
Sigma-Aldrich
N-Methylaniline, purum, ≥98.0% (GC)
Sigma-Aldrich
Pyridine hydrochloride, 98%
Sigma-Aldrich
Aniline, ReagentPlus®, 99%
Sigma-Aldrich
Aniline, ACS reagent, ≥99.5%
Sigma-Aldrich
Diethylamine hydrobromide, 98%
Sigma-Aldrich
Dicyclohexylamine, 99%
Sigma-Aldrich
N-Methylaniline, 98%
Sigma-Aldrich
N-Methylaniline, ≥99%
Supelco
Sinapic acid, matrix substance for MALDI-MS, ≥99.0% (T)
Sigma-Aldrich
Sinapic acid, ≥98%, powder
Supelco
N-Methylaniline, analytical standard
Sigma-Aldrich
Pyridine, anhydrous, 99.8%
Sigma-Aldrich
Diethylamine, purified by redistillation, 99.5%
Sigma-Aldrich
Aniline-1-13C, 99 atom % 13C
Sigma-Aldrich
Pyridine hydrobromide, 98%
Supelco
Pyridine, analytical standard
Sigma-Aldrich
Diethylamine, ≥99.5%
Sigma-Aldrich
Aniline hydrochloride, ≥99%
Supelco
Aniline solution, certified reference material, 5000 μg/mL in methanol
Sigma-Aldrich
Pyridine, ≥99%
Sigma-Aldrich
Pyridine, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Diethylamine, puriss. p.a., ≥99.5% (GC)
Sigma-Aldrich
Pyridine, ACS reagent, ≥99.0%