Electrospray mass spectrometry for characterizing polyglycerols and the effects of adduct ion and cone voltage

Abstract

Polyglycerol intermediates have been characterized by liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI). Linear and cyclic components from n = 2-23 in a sample of decaglycerol, for example, have been resolved in the second dimension or mass axis. Molecular weight (MW) distributions for tri-, hexa-, and decaglycerol products have been analyzed as a function of cone voltage and adduct ion (H + , Li + , Na + , K + , Rb + , Cs + , and NH 4 + ). A different combination is required to obtain a reliable MW distribution for each polyglycerol intermediate. The best distribution obtained by ESI/MS is determined by comparing the calculated hydroxyl number and cyclic content to that obtained by wet chemistry and gas chromatography, respectively. Once ESI/MS conditions are established, the distribution can be used, for the first time in polyglycerol analysis, to calculate important parameters such as number average MW, weight average MW, polydispersity, % cyclics, hydroxyl number, wt% above n = 6, etc.Polyglycerols are intermediates for polyglycerol fatty esters, used as additives in the food and personal-care industries. Knowledge of the polyglycerol distribution will help relate composition to performance, optimize process chemistry, and produce newly tailored products. Gas chromatography (GC) of an acetylated polyglycerol can resolve linear and cyclic components only up to hexad chains (1). Furthermore, the peak intensities in the gas chromatogram are progressively attenuated with increasing degree of polymerization. Highperformance liquid-chromatography (HPLC) with refractive index (RI) detection and a carbohydrate column partially resolves polymers up to n = 12, but cyclic and linear components (larger than diglycerol) are not resolved (2). Supercritical fluid chromatography of silanized polyglycerols shows peak maxima up to n = 10. Higher molecular weight (MW) polymers elute, but still not all cyclic and linear components are resolved (3). Liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI) has advantages compared with all the above techniques since all components FIG. 1. (A) General structure for polyglycerol. (B) Structures for linear and branched diglycerol. (C) Possible structures for monocyclic diglycerol.

Analysis of complex mixtures of polyglycerol fatty esters using liquid chromatography and high-resolution mass spectrometry: Retention, structural and relative composition study

“…The PG3 + 1C18 monoester was identified at an rt of 1.32, and the corresponding cyclic PG3 [1] + 1 C18 was found at the same rt of 1.32, related to ESI-induced dehydration and at rt 1.96, also related to an increase in hydrophobic and steric interactions with the stationary phase (Table S5). The same analysis can be achieved for all samples, for a precise characterisation of these specific classes of cyclic PGEs, in accordance with the previous work of Chaimbault et al [21] and Crowther et al [22]. The detailed PGEs analysis with one or two water loss is identical to the analysis performed with the U-HPLC method.…”

Enzymatic Synthesis of Polyglycerol Fatty Acid Esters and Their Application as Emulsion Stabilizers

“…The composition of polyglycerols was analyzed by high-performance liquid chromatography (HPLC) according to a modified method described by Crowther et al 21 After purification by MD, the purity of the polyglycerol product was up to 86.33% and included 68.37% diglycerol, 13.13% triglycerol, and 3.18% tetraglycerol (data not shown).…”

Normalized mass mapping of Orbitrap data to define complex, polyglycerol‐based raw material compositions

“…A high‐performance liquid chromatography (HPLC) electrospray ionization (ESI), low‐resolution mass spectrometry (LRMS) study of unesterified polyglycerols was reported some time ago. Reasonable agreement was obtained between the MS‐based method and the traditional wet chemical method for the 'hydroxyl number' 6. Since ESI source designs have changed significantly over the last decade, it would be difficult to extrapolate some of the findings to current results using state‐of‐the‐art instrumentation.…”