N-(1-naphthyl) ethylenediamine dinitrate: a new matrix for negative ion MALDI-TOF MS analysis of small molecules.
An organic salt, N-(1-naphthyl) ethylenediamine dinitrate (NEDN), with rationally designed properties of a strong UV absorbing chromophore, hydrogen binding and nitrate anion donors, has been employed as a matrix to analyze small molecules (m/z < 1000) such as oligosaccharides, peptides, metabolites and explosives using negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Compared with conventional matrixes such as α-cyano-4-hydroxycinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB), NEDN provides a significant improvement in detection sensitivity and yields very few matrix-associated fragment and cluster ions interfering with MS analysis. For low-molecular-weight saccharides, the lowest detection limit achieved ranges from 500 amol to 5 pmol, depending on the molecular weight and the structure of the analytes. Additionally, the mass spectra in the lower mass range (m/z < 200) consist of only nitrate and nitric acid cluster ions, making the matrix particularly useful for structural identification of oligosaccharides by post-source decay (PSD) MALDI-MS. Such a characteristic is illustrated by using maltoheptaose as a model system. This work demonstrates that NEDN is a novel negative ion-mode matrix for MALDI-MS analysis of small molecules with nitrate anion attachment.
Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, The Chinese Academy of Sciences, Beijing, China.
Rui
R
Chen
Suming
S
Chen
Caiqiao
C
Xiong
Xunlei
X
Ding
Chih-Che
CC
Wu
Huan-Cheng
HC
Chang
Shaoxiang
S
Xiong
Zongxiu
Z
Nie
D000838:Anions / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry*; D005841:Gentisates / Q000737:chemistry; D057230:Limit of Detection; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D000838:Anions; D003373:Coumaric Acids; D005029:Ethylenediamines; D005841:Gentisates; D009844:Oligosaccharides; C008588:N-(1-naphthyl)ethylenediamine; C007175:alpha-cyano-4-hydroxycinnamate; C010925:2,5-dihydroxybenzoic acid