Single‐pump bi‐dimensional LC applied to the characterization of derivatized fatty alcohol ethoxylates

Abstract

A column selection valve and a 6-port 2-position injection valve were combined to implement bi-dimensional LC in a system driven by a single pump. The system was applied to the separation of linear fatty alcohol ethoxylates with 12-18 carbon atoms in the hydrocarbon moiety, previous derivatization with diphenic anhydride. Separation on the first separation dimension (C(1)) was carried out with a propyl-diol column and an acetonitrile/aqueous ammonium acetate gradient. Fatty alcohol ethoxylate hydrocarbon series (oligomers with the same number of carbon atoms in the alkyl chain but differing in the number of ethylene oxide units) were resolved without distinguishing the oligomers within the series. Selected segments of the eluate of C(1) were transferred to the second column (C(2)), where the successive oligomers within the isolated series were resolved by using either an octyl-silica or a pentafluoro-phenyl-propyl column and an acetonitrile/water gradient. Flow stopping at C(1) during system re-conditioning and elution along the second dimension did not produce any noticeable band broadening. Overlapping of the non-ethoxylated and mono-ethoxylated oligomers with other oligomers within the series was avoided by eluting the pentafluoro-phenyl-propyl column at low temperatures (3 degrees C).

Multidimensional Mass Spectrometry Coupled with Separation by Polarity or Shape for the Characterization of Sugar-Based Nonionic Surfactants

“…High-performance liquid chromatography (HPLC or LC) with UV–vis detection has been used widely to identify the components of nonionic surfactants. − Unfortunately, most modern surfactants do not possess UV–vis absorbing chromophores due to increased environmental concerns. Although refractive index (RI) and evaporative light scattering (ELS) detectors can be used in such cases, these detection systems (like UV–vis detectors) lack the specificity needed to unravel the complexity of nonionic surfactant blends. These problems are largely bypassed by coupling LC to mass spectrometry (MS) which reveals specific compositional and structural insight.…”

Comparison of critical methods developed for fatty acid analysis: A review

“…Derivatization is mostly designed to be used in pre‐column mode . Some of the commonly used derivatization reagents are naphthoyl chloride , phthalic anhydride , diphenic anhydride , and 2‐sulfobenzoic anhydride .…”

Analytical methods for the characterization and determination of nonionic surfactants in cosmetics and environmental matrices

“…Direct UV detection is possible with APs and APEs, but AEs should be derivatized. [139][140][141][142][143] APEs are detected at 277-280 nm. For the analysis of APEs in environmental samples, HPLC with uorescence detection (excitation and emission wavelengths at 230 and 302-310 nm, respectively) is most simple and suitable.…”

“…Some authors have employed C8 columns for the complete separation of APEs up to 17 EO units in a single chromatographic run. 65,68,73,79,[139][140][141][142][143]149,150 Separation of APEs using mixed-mode chromatography has also been reported. 146 This HPLC mode combines size exclusion and RP, so allowing separation based on the number of EO units and hydrophobicity, respectively.…”