1 research outputs found
Multidimensional Mass Spectrometry Coupled with Separation by Polarity or Shape for the Characterization of Sugar-Based Nonionic Surfactants
Mass spectrometry (MS) and tandem
mass spectrometry (MS/MS) were
interfaced with ultra-performance liquid chromatography (UPLC) and
ion mobility (IM) separation to characterize a complex nonionic surfactant,
consisting of a methylated glucose core (glucam) conjugated with poly(ethylene
oxide) (PEO<sub><i>n</i></sub>) branches that were partially
esterified with stearic acid to form ethoxylated glucam (PEO<sub><i>n</i></sub>-glucam) stearates. Reverse-phase LC-MS afforded
fast separation according to polarity into five major fractions. Accurate
mass measurements of the ions in the mass spectra extracted from these
fractions enabled conclusive identification of six components in the
surfactant, including PEO<sub><i>n</i></sub>-glucam mono-,
di-, and tristearates as well as free and esterified PEO<sub><i>n</i></sub> as byproducts. MS/MS experiments provided corroborating
evidence for the fatty acid content in each fraction based on the
number of stearic acid losses observed. With IM-MS, the total surfactant
ions were separated according to charge and shape into four distinct
bands. Extracted mass spectra confirmed the presence of two disaccharide
stearates in the surfactant, which were undetectable by LC-MS. PEO<sub><i>n</i></sub>-glucam tristearates were, however, not observed
upon IM-MS. Hence, LC-MS and IM-MS unveiled complementary compositional
insight. With each method, certain components were particularly well
separated from other ingredients (by either polarity or shape), to
be detected with confidence. Consequently, combined LC-MS and IM-MS
offer a superior approach for the characterization of surfactants
and other amphiphilic polymers and for the differentiation of similarly
composed amphiphilic blends. It is finally noteworthy that NH<sub>4</sub><sup>+</sup> charges minimized chemical noise in MS mode and
Li<sup>+</sup> charges maximized the fragmentation efficiency in MS/MS
mode