Development of supercritical fluid chromatography coupled with mass spectrometry method for characterization of a nonionic surfactant and comparison with liquid chromatography coupled with mass spectrometry method

Abstract

The supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) method and liquid chromatography coupled with mass spectrometry (LC-MS) method were developed for the separation and characterization of poly (ethylene oxide) methyl glucose sesquistearate (PEO-Glu-sesquistearate). The products of PEO-Glusesquistearate are composed of complex oligomers. The relationship between molecular structure of these oligomers and chromatographic retention behavior in both SFC and LC were discussed and compared. As compared with LC, hydrophobic moieties of compounds favor the fast elution in SFC. The different series can be better separated by LC, while the homologues compounds in same series can be better separated by SFC, and SFC-MS provided more comprehensive structural information. Different series such as PEO-distearate, PEO-stearate, PEO, PEO-Glu-tetrastearate, PEO-Glu-tristearate, PEO-Glu-distearate, PEO-Glu-stearate, and PEO-Glu were identified by MS/MS. K E Y W O R D S chromatographic retention behavior, fragment identification, LC-MS, nonionic surfactant, SFC-MS 1 | INTRODUCTION The poly (ethylene oxide) methyl glucose sesquistearate (PEO-Glusesquistearate) is a sugar-based nonionic surfactants with low toxicity and high surface activity, which is widely used as emulsifiers, solubilizers, and stabilizers in cosmetics 1 , drugs 2 , and biodegradation media 3 . PEO-Glu-sesquistearate, as amphiphilic polymers, contains varying quantities of by-products. The formulation of the by-products is complicated, which includes PEO, PEO stearate(s), and PEO-methyl glucose stearate(s) with varying numbers of EOs at varying degrees of esterification (none, mono-, di-, tri-, and quadri-). The structure of PEO-methyl glucose stearate is shown in

Analysis of surfactants by mass spectrometry: Coming to grips with their diversity

“…As compared with LC, hydrophobic moieties of compounds favor the fast elution in SFC. Whist different series can be separated by LC, homologue compounds of the same series can be better separated by SFC, which coupled with MS provided very useful structural information (Pan et al, 2020). The SFC-MS was used to analyse alkyl polyglyceryl ethers (Fan et al, 2015), offering further understanding on the product surfactant composition after etherification and it was also developed for the fast determination of alkylphenol ethoxylates in leafy vegetables (Jiang et al, 2017), thus demonstrating its usefulness for anionic surfactant analysis.…”

“…Because of the existence of many alkyl homologues, lack of chromophores, high polarity, and thermal instability, nonaromatic surfactants are difficult to analyse. Several techniques for their determination have been reported, including titration (Fielden & Claesson, 1998), Fourier‐transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy (Jain et al, 2012; Lee et al, 2016), attenuated total reflectance with FTIR (Carolei & Gutz, 2005), ion chromatography with suppressed or nonsuppressed conductivity detection (IC‐CD) (Cataldi et al, 2007; Levine et al, 2000), gas chromatography coupled to mass spectrometry (GC‐MS) (Ding & Liao, 2001; Ding & Tsai, 2003), capillary electrophoresis with UV detection (Liu & Ding, 2004; Piera et al, 1997), high performance liquid chromatography coupled with mass spectrometry (HPLC‐MS) or evaporative light scattering detector (HPLC‐ELSD) (Crescenzi et al, 1995), and supercritical fluid chromatography coupled with mass spectrometry (SFC‐MS) (Ma et al, 2019; Pan et al, 2020). Among the above‐mentioned techniques, the chromatographic ones have many advantages for analysing surfactant mixtures.…”

“…Conversely, HPLC is applicable to surfactant mixtures regardless their molecular charge (Morelli & Szajer, 2001, 2000) and can be coupled with different detectors, such as mass spectrometers and UV‐Vis diode array, without any derivatization reactions. However, low polymer solubility and increased solution viscosity, with the ensuing issues of sample injection and elution, as well as relatively low chromatographic resolution of individual oligomers, make its use challenging (Pan et al, 2020; Schmitt et al, 1990). As an alternative, stand‐alone shotgun MS has been widely used for surfactant analysis, and MS provides a wide range of advantages, such as supplying key structural characterization by tandem mass spectrometry (MS/MS).…”

Multidimensional Mass Spectrometry of Multicomponent Nonionic Surfactant Blends

“…This issue is partly addressed by choosing mass spectrometry (MS) detection, which employs a molecule-specific property, viz., mass, for compound detection and identification. Indeed, GC–MS , as well as LC–MS using high-performance liquid chromatography (HPLC), ,, ultraperformance liquid chromatography (UPLC), ,, or supercritical fluid chromatography (SFC) , have all demonstrated success in characterizing these types of mixtures. Unfortunately, as mixture complexity continues to increase, so does the probability that multiple components have very similar polarities and, thus, similar elution times.…”

Coceth sulfate characterization by electrospray ionization tandem mass spectrometry

“…Because of the existence of many alkyl homologues, lack of chromophores, high polarity, and thermal instability, it is difficult to analyse non‐aromatic surfactants in commercial products. Despite this, several techniques for their determination have been reported, including titration, 13,14 Fourier‐transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy, 15–20 attenuated total reflectance (ATR) combined with FTIR, 21 ion chromatography with suppressed or non‐suppressed conductivity detection (IC‐CCD), 22,23 gas chromatography coupled to mass spectrometry (GC/MS), 24,25 capillary electrophoresis (CE) with UV detection, 26–28 high‐performance liquid chromatography coupled with mass spectrometry (HPLC/MS) or evaporative light scattering detector (HPLC‐ELSD), 29–31 and supercritical fluid chromatography coupled with mass spectrometry (SFC/MS) 32 . Among the above‐mentioned techniques, the chromatographic ones have many advantages for analysing surfactant mixtures.…”