Analysis of ethoxylated fatty amines. Comparison of methods for the determination of molecular weight

Abstract

Specific lengths of the fatty and polyoxyethylene chains of ethoxylated fatty amines are critical to their performance in specific applications, and thus the ability to characterize these surfactants accurately is crucial. Normal-phase high-performance liquid chromatography (HPLC) and matrixassisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry methods were developed to determine with accuracy the molecular weight and degree of ethoxylation of ethoxylated fatty amines. Ethoxylated fatty amines were analyzed using these methods, and comparison was made to molecular weight determinations using proton nuclear magnetic resonance (NMR), neutralization equivalent weight, and hydroxyl value methods. Molecular weight results from normalphase HPLC analyses were in very good agreement with MALDI-TOF results, typically varying less than one ethylene oxide unit. A reversed-phase HPLC method was developed to determine concentrations of polyethylene glycols (PEG) and fatty homologs. PEG interfered with molecular weight determinations by NMR, neutralization equivalent weight, and hydroxyl value methods. PEG caused no interference with molecular weight determinations by normal-phase HPLC and MALDI-TOF methods.

Quantum chemical calculations, synthesis and corrosion inhibition efficiency of ethoxylated-[2-(2-{2-[2-(2-benzenesulfonylamino-ethylamino)-ethylamino]-ethylamino}-ethylamino)-ethyl]-4-alkyl-benzenesulfonamide on API X65 steel surface under H2S environment

“…Addition of inhibitor molecules to the aggressive medium produces a positive shift in the open circuit potential due to the retardation of the anodic reaction, which is the process of metal dissolution reaction [29]. From the obtained polarization curves, it is clear that the corrosion current densities (i corr .)…”

Synthesis and Surface Active Properties of Ethoxyalted 4,5-Dihydroimidazoline Surfactants

“…The ethoxylation was represented by the third step in Scheme 1. [12][13][14] The general chemical structures, IUPAC (International Union of Pure and Applied Chemistry) name, and abbreviation of representative compounds (amide, imidazoline, and ethoxylate) are shown in Table 2. Fourier transform infrared spectroscopy (FTIR) was used to confirm their chemical structures (Figures 1 and 2).…”

Characterisation of alkylamine ethoxylates (ANEOs) in commercial herbicide formulations using liquid chromatography/electrospray ionisation mass spectrometry

“…A great variety of analytical methods have been used for glyphosate determination,9 but few attempts have been made to analyse ANEOs 3, 10–12. These have involved chromatographic separation followed by fluorescence,3 evaporative light‐scattering mass detection10 or mass spectrometric11, 12 detection of the analytes.…”

“…A great variety of analytical methods have been used for glyphosate determination,9 but few attempts have been made to analyse ANEOs 3, 10–12. These have involved chromatographic separation followed by fluorescence,3 evaporative light‐scattering mass detection10 or mass spectrometric11, 12 detection of the analytes. Of these techniques, only mass spectrometry (MS) allows the simultaneous determination of both the alkyl and the ethoxymer homologues as the others require a two‐step process involving the prior separation of the alkyl homologues by reversed‐phase liquid chromatography (LC) followed by the separation of the individual oligomers by normal‐phase LC 3, 10…”

“…Of these techniques, only mass spectrometry (MS) allows the simultaneous determination of both the alkyl and the ethoxymer homologues as the others require a two-step process involving the prior separation of the alkyl homologues by reversed-phase liquid chromatography (LC) followed by the separation of the individual oligomers by normal-phase LC. 3,10 Other non-ionic surfactants such as alkyphenol ethoxylates 13,14 and alcohol ethoxylates 15 with similar characteristics to ANEO compounds have been widely characterised by LC/MS and determined mainly in environmental samples. Considering the effectiveness of LC/MS in determining alkyphenol ethoxylates and the methods previously reported for the determination of ANEOs, this technique seems to be the most suitable 16,17 as MS is able to identify the different alkylamine homologues.…”