AN INNOVATIVE DERIVATIZATION METHOD FOR SIMULTANEOUS DETERMINATION OF URONIC ACIDS AND NEUTRAL AND AMINO SUGARS IN COEXISTING SAMPLES BY HPLC-ESI-MS/MS²

Abstract

To eliminate lactone byproduct of uronic acid and avoid a desalting procedure, a novel strategy of saccharides derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) was developed for analysis of uronic acids and neutral and amino sugars in coexisting samples by HPLC-ESI-MS, initially employing triethylamine as a catalyst instead of the conventional sodium hydroxide. The established method was greatly simplified compared to conventional methods, and the derivatives could be directly analyzed by ESI-MS without a tedious desalting procedure, avoiding loss of the sample. The assay showed excellent linearity over the range 0.025–1.60 µmol L⁻¹ (r > 0.999) and detection limits ranging from 0.01 to 0.09 pmol. The intra-day precision was found to be satisfactory (RSD <2.7%). Mean recoveries ranged from 93.74% to 104.23%. Thirteen PMP-labeled monosaccharides including uronic acids and neutral and amino sugars were baseline separated on a C18 column and detected by HPLC-ESI-MS/MS² within only 22 min. The assay was successfully applied to sugar composition analysis of polysaccharides ASP from Artemisia sphaerocephala Krasch.

Keywords:

• 1-phenyl-3-methyl-5-pyrazolone (PMP)
• amino sugar
• derivatization
• HPLC-ESI-MS
• saccharide
• uronic acid

ACKNOWLEDGMENTS

Financial support was provided by National Natural Science Foundation of China (NSFC) (30870548), Program for New Century Excellent Talents in Universities (NCET-08-0893), Hi-Tech Research and Development Program of China (2007AA10Z338 and 2007AA091601), and the Foundation of Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education in Northwest University (KH09019).

Notes

Note: M represents molecular weight of PMP-labeled monosaccharides; -, not detected.

^a denotes fragment ion [M-H₂O + H]⁺.

^b denotes fragment ion [M-NH₃ + H]⁺.

^c denotes fragment ion [M-PMP-2H₂O-CH₂O-CHNH₂ + H]⁺.

^d denotes fragment ion [M-PMP-3H₂O-CHNHCOCH₃ + H]⁺.

^e denotes fragment ion [M-PMP-2H₂O-COO⁻ + H]⁺.

^f denotes fragment ion [M-PMP-2H₂O-CH₂CH₂O + H]⁺.

[W + H]⁺: [M-H₂O-C_mH_2mO_m + H]⁺ (m = n − 2, n denotes the number of carbonatoms in neutral saccharide molecule); [M-NH₃-C_mH_2mO_m + H]⁺ (m = n − 2, n denotes the number of carbonatoms in amino saccharide molecule); [M-H₂O-C_mH_2m-2O_m+1 + H⁺ (m = n − 2, n denotes the number of carbonatoms in uronic acid molecule); [M-H₂O-C_mH_2mO_m-1 + H]⁺ (m = n-2, n denotes the number of carbonatoms in deoxysugar molecule).

[Y + H]⁺: [M-PMP-(H₂O)n'-C_mH_2mO_m + H]⁺ (n' = 0, 1, 2, 3; m = n − 1, n denotes the number of carbonatoms in neutral saccharide molecule); [M-PMP-(H₂O)n'-C_mH_2mO_m-CHNH₂ + H]⁺ (n' = 0, 1, 2, 3; m = n − 2, n denotes the number of carbonatoms in amino saccharide molecule); [M-PMP-(H₂O)n'-C_mH_2m-2O_m+1 + H]⁺ (n' = 0, 1, 2, 3; m = n − 1, n denotes the number of carbonatoms in uronic acid molecule); [M-PMP-(H₂O)n'-C_mH_2mO_m-1 + H]⁺ (n' = 0, 1, 2, 3; m = n − 1, n denotes the number of carbonatoms in deoxysugar molecule).