Detection of water-soluble vitamins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using porphyrin matrices.
The detection of water-soluble vitamins B(1), B(2), B(6), B(12) and C by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOFMS) was attempted by studying 17 porphyrin matrices. Comparative studies of porphyrin matrices, useful mass spectral window, matrix/analyte molar ratio (M/A), ultraviolet-visible absorption characteristics and quantitative results were made. Most porphyrin matrices provide a useful mass spectral window in the low-mass range. The optimal M/A increases with increasing molecular mass of the vitamin. Vitamin B(12) possesses the highest molecular mass and requires a higher M/A. The presence of hydroxyl or carboxyl groups in the porphyrin is an indicator of a useful MALDI matrix. Vitamins B(2) and B(6) were readily ionized upon irradiation with a 337 nm laser without the use of any porphyrin matrix. Improved linearity and sensitivity of the calibration curves were obtained with samples prepared with a constant M/A. The limits of detection and quantitation are at the picomole level. The results indicate that MALDI-TOFMS with porphyrin matrices is a rapid and viable technique for the detection of low molecular mass water-soluble vitamins.
Chen
Yi-Ting
YT
Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan.
Ling
Yong-Chien
YC
D007202:Indicators and Reagents; D011166:Porphyrins / Q000737:chemistry*; D012015:Reference Standards; D012997:Solvents; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D014815:Vitamins / Q000737:chemistry*
D007202:Indicators and Reagents; D011166:Porphyrins; D012997:Solvents; D014815:Vitamins