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Characterisation of castor oil by on‐line and off‐line non‐aqueous reverse‐phase high‐performance liquid chromatography–mass spectrometry (APCI and UV/MALDI)
Author(s) -
Stübiger Gerald,
Pittenauer Ernst,
Allmaier Günter
Publication year - 2003
Publication title -
phytochemical analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 72
eISSN - 1099-1565
pISSN - 0958-0344
DOI - 10.1002/pca.724
Subject(s) - chemistry , atmospheric pressure chemical ionization , ricinoleic acid , chromatography , mass spectrometry , stearic acid , castor oil , mass spectrum , oleic acid , analytical chemistry (journal) , chemical ionization , ionization , ion , organic chemistry , biochemistry
A non‐aqueous reverse‐phase HPLC method, based on two columns in series, has been used to separate the major triacylglycerols (TAGs) from commercial castor oil and to perform either on‐line negative ion atmospheric pressure chemical ionisation (APCI), or off‐line positive ion matrix‐assisted laser desorption ionisation (MALDI)/MS. The resulting Mass Spectra showed chloride‐attached TAG molecules [M + Cl] − in the case of negative‐ion APCI, and sodium‐attached TAG molecules [M + Na] + in the case of positive‐ion MALDI. For MALDI time‐of‐ight (TOF)/MS, a liquid binary matrix system consisting of sodium ferrocyanide and glycerol was applied, resulting in excellent TAG sensitivity, which was necessary for the determination of trace amounts of TAGs in castor oil. Both techniques allowed unambiguous molecular mass determination of the intact TAG molecules with no thermal degradation. Furthermore, seamless post source decay (PSD) fragment ion analysis by means of a curved eld reector TOF mass spectrometer allowed the determination of the fatty acid composition of each individual TAG. Castor oil contained eight different TAGs which were successfully determined by both APCI and MALDI techniques. In each TAG, at least two units of 12‐hydroxy‐9‐octadecenoic acid (ricinoleic acid) were present. The following fatty acids were determined by seamless PSD fragment ion analysis and APCI/MALDI molecular mass determination as TAG substructures: ricinoleic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, dihydroxy stearic acid and eicosenoic acid. Triricinolein was the dominating TAG. Copyright © 2003 John Wiley & Sons, Ltd.