Analysis of some commercial polysorbate formulations using matrix-assistedlaser desorption/ionization time-of-flight mass spectrometry

Analyses of polysorbate formulations (Tween(R)20, Tween(R)40, Tween(R)60, a nd Tween(R)80) by matrix-assisted laser desorption/ionization time-of-fligh t mass spectrometry (MALDI-TOFMS) reveal a complex mixture of oligomers tha t include polyethylene glycols, polyethylene glycol esters, isosorbide poly ethoxylates, sorbitan polyethoxylates, polysorbate monoesters, polysorbate diesters, and sorbitol polyethoxylate esters, The MALDI-TOF mass spectra fo r these formulations show the presence of sodiated molecules in which the m ajor signals are attributed to the presence of polyethylene glycols, isosor bide polyethoxylates, and sorbitan polyethoxylates, Additionally, the compl exity of the spectra was correlated to the constituent fatty acid moieties in the polysorbate formulations. Thus Tween(R)20 showed the presence of pol ysorbate monolaurates, polysorbate monomyristates, and polysorbate monopalm itates, Tween(R)40 contained polysorbate mono- and dipalmitates. Tween(R)60 contained polysorbate monopalmitates and polysorbate monostearates. For th e Tween(R)80, mass assignment for polysorbate monooleates and polysorbate d ioleates was equivocal, because both of these oligomeric series have the sa me molecular weight as the sorbitan polyethoxylates, and thus the Tween(R)8 0 MALDI-TOF spectrum appeared to be the least complicated of the four comme rcial polysorbate formulations. Copyright (C) 2000 John Wiley & Sons, Ltd.