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Abstract No.: MoP-002
Session: Carbohydrates
Presentation date: Mon, Aug 28, 2006
Presentation time: 14:30 – 16:00

9-aminoacridine as a Matrix for Negative Ion Mode Matrix-Assisted Laser Desorption/Ionization of Carrageenan Polysaccharides

Vincent Guerineau1, Aristotelis Antonopoulos2, Michel Lafosse2, Olivier Laprevote1

1 ICSN-CNRS, Gif-sur-Yvette, France
2 ICOA-CNRS - Universite d'Orleans, Orleans, France

Correspondence address: Vincent Guerineau, ICSN-CNRS, Mass Spectrometry Laboratory, Avenue de la Terrasse, Gif-sur-Yvette, 91198 France.

Keywords: Carbohydrates; MALDI; Matrix Development in MALDI or FAB; Negative Ion.

Novel aspect: New MALDI matrix for acidic products.

 

Carrageenan is the generic name for a family of natural, water soluble, partially sulphated galactans isolated from red seaweed (Rhodophyta), with a primary backbone structure based on alternatively 3-linked, β-D-galactose (unit G) and 4-linked, α-D-galactose (unit D).1 These glycans are well-known because of their use in the food industry as additives2 but have also some numerous biological properties. They mediate cell-cell communication in host-pathogen interactions3 and present antiviral activities.4 The carrageenan family has three main branches named kappa (κ), iota (ι) and lambda (λ) which are differentiated by the number of sulphate groups per monomer.

Enzymatically digested oligosaccharides of carrageenans were previously analyzed using mass spectrometry.5,6 In our study, we used MALDI-TOF mass spectrometry in the negative-ion mode with 9-Aminoacridine (9-AA) as matrix. The previous success of 9-AA with negative ionization7,8 suggested that it may be a useful and simple approach for carrageenans analysis.

Several matrices (9-AA, 2, 4, 6-THAP, 6-Aza-2-thiothymine, nor-harmane) were tested using two deposition methods (thin layer and dried droplet). In all cases, 9-AA as matrix yielded a far superior signal. Specially, 9-AA gave more intense molecular peak with less desulphation. Moreover, we obtained high resolution (dM/M 15000) that allowed us, with appropriate internal standards (i.e acidic molecules) to make accurate mass measurement with a mass error of less than 10 ppm. At last, we made MS/MS analysis on a tandem quadrupole/orthogonal TOF mass spectrometer fitted with a MALDI ion source that gave us more structural information.

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