Composition analysis of detergents of the polyoxyethylene type: comparison of thin-layer chromatography, reversed-phase chromatography and matrix-assisted laser desorption/ionization mass spectrometry
“…The mean value of EO group per surfactant is roughly 23, the value given by the manufacturer. This result confirms the findings from previous literature studies [ 77 , 80 ]. Figure A3 MALDI-TOF spectra of BrijL23 from a pure HCCA matrix and from HCCA matrices upon addition of or salt.…”
Section: Figure A1supporting
confidence: 93%
“…The mean value of EO group per surfactant is roughly 23, the value given by the manufacturer. This result confirms the findings from previous literature studies [ 77 , 80 ].…”
Section: Figure A1supporting
confidence: 93%
“…The different peaks of each set are spaced by a mass/charge ratio of , corresponding to the mass of ethylene oxide (EO, ) unit. Previous studies revealed that the commercially available Tween20 is often a mixture of various compounds [ 77 , 78 , 79 , 80 , 81 , 82 ]. The two major components found in this study are shown in Figure A2 .…”
Section: Figure A1mentioning
confidence: 99%
“…Previous studies revealed that the commercially available Tween20 is often a mixture of various compounds [ 77 , 78 , 79 , 80 , 81 , 82 ]. The two major components found in this study are shown in Figure A2 .…”
Aqueous solutions of a nonionic surfactant (either Tween20 or BrijL23) and an anionic surfactant (sodium dodecyl sulfate, SDS) are investigated, using small-angle neutron scattering (SANS). SANS spectra are analysed by using a core-shell model to describe the form factor of self-assembled surfactant micelles; the intermicellar interactions are modelled by using a hard-sphere Percus–Yevick (HS-PY) or a rescaled mean spherical approximation (RMSA) structure factor. Choosing these specific nonionic surfactants allows for comparison of the effect of branched (Tween20) and linear (BrijL23) surfactant headgroups, both constituted of poly-ethylene oxide (PEO) groups. The nonionic–anionic surfactant mixtures are studied at various concentrations up to highly concentrated samples (ϕ ≲ 0.45) and various mixing ratios, from pure nonionic to pure anionic surfactant solutions. The scattering data reveal the formation of mixed micelles already at concentrations below the critical micelle concentration of SDS. At higher volume fractions, excluded volume effects dominate the intermicellar structuring, even for charged micelles. In consequence, at high volume fractions, the intermicellar structuring is the same for charged and uncharged micelles. At all mixing ratios, almost spherical mixed micelles form. This offers the opportunity to create a system of colloidal particles with a variable surface charge. This excludes only roughly equimolar mixing ratios (X≈ 0.4–0.6) at which the micelles significantly increase in size and ellipticity due to specific sulfate–EO interactions.
“…The mean value of EO group per surfactant is roughly 23, the value given by the manufacturer. This result confirms the findings from previous literature studies [ 77 , 80 ]. Figure A3 MALDI-TOF spectra of BrijL23 from a pure HCCA matrix and from HCCA matrices upon addition of or salt.…”
Section: Figure A1supporting
confidence: 93%
“…The mean value of EO group per surfactant is roughly 23, the value given by the manufacturer. This result confirms the findings from previous literature studies [ 77 , 80 ].…”
Section: Figure A1supporting
confidence: 93%
“…The different peaks of each set are spaced by a mass/charge ratio of , corresponding to the mass of ethylene oxide (EO, ) unit. Previous studies revealed that the commercially available Tween20 is often a mixture of various compounds [ 77 , 78 , 79 , 80 , 81 , 82 ]. The two major components found in this study are shown in Figure A2 .…”
Section: Figure A1mentioning
confidence: 99%
“…Previous studies revealed that the commercially available Tween20 is often a mixture of various compounds [ 77 , 78 , 79 , 80 , 81 , 82 ]. The two major components found in this study are shown in Figure A2 .…”
Aqueous solutions of a nonionic surfactant (either Tween20 or BrijL23) and an anionic surfactant (sodium dodecyl sulfate, SDS) are investigated, using small-angle neutron scattering (SANS). SANS spectra are analysed by using a core-shell model to describe the form factor of self-assembled surfactant micelles; the intermicellar interactions are modelled by using a hard-sphere Percus–Yevick (HS-PY) or a rescaled mean spherical approximation (RMSA) structure factor. Choosing these specific nonionic surfactants allows for comparison of the effect of branched (Tween20) and linear (BrijL23) surfactant headgroups, both constituted of poly-ethylene oxide (PEO) groups. The nonionic–anionic surfactant mixtures are studied at various concentrations up to highly concentrated samples (ϕ ≲ 0.45) and various mixing ratios, from pure nonionic to pure anionic surfactant solutions. The scattering data reveal the formation of mixed micelles already at concentrations below the critical micelle concentration of SDS. At higher volume fractions, excluded volume effects dominate the intermicellar structuring, even for charged micelles. In consequence, at high volume fractions, the intermicellar structuring is the same for charged and uncharged micelles. At all mixing ratios, almost spherical mixed micelles form. This offers the opportunity to create a system of colloidal particles with a variable surface charge. This excludes only roughly equimolar mixing ratios (X≈ 0.4–0.6) at which the micelles significantly increase in size and ellipticity due to specific sulfate–EO interactions.
“…The MALDI spectrum of NM-300K was complex, but apparently 5 series of polyethoxylates could be discerned. These observations were not contrary to the description of NM-300K [53] which was added 4 wt.% polyoxyethylene glycerol trioleate (Tagat ® TO) (see [56,64]) and 4 wt.% polyoxyethylene sorbitan monolaurate (Tween ® 20) (see [65]) as dispersion stabilizers. Thus MALDI-TOF-MS showed the polymeric nature of the associated organic compounds and GC-MS indicated the identity of the end groups.…”
Manufactured nanomaterials (MNMs) often have a surface-chemical modification in order to tailor their physicochemical properties, including also powder properties and miscibility. Surface-chemical modifications may influence the toxicological properties of the MNM, but the specific chemistry and extent are rarely described in detail in suppliers’ technical data sheets. Chemical and quantitative information on any surface-chemical treatment, coating and functionalization are required for chemicals registration in Europe. Currently there is no globally accepted and documented approach to generate such data. Consequently, there is a continued research need to establish a structured approach to identify and quantify surface-chemical modifications. Here we present a tiered approach starting with screening for mass-loss during heating in a furnace or thermogravimetric analysis (TGA) followed by solvent extraction, and analysis by several mass spectrometry (MS) techniques depending on the target analytes. Thermal treatment was assumed to be able to quantify the amount of organic coating and MS was used to identify the extractable organic coatings after pressurized liquid extraction (PLE) using methanol at 200 °C. Volatile organic compounds in extracts were identified with gas chromatography and MS (GC-MS), non-volatile organic compounds with liquid chromatography MS (LC-MS), and polymeric compounds with matrix-assisted laser desorption ionization time-of-flight MS (MALDI-TOF-MS). The approach was demonstrated by analysis of 24 MNM, comprising titanium dioxide, synthetic amorphous silica, graphite, zinc oxide, silver, calcium carbonate, iron oxide, nickel-zinc-iron oxide, and organoclay. In extracts of 14 MNMs a range of organic compounds were identified and the main groups were silanes/siloxanes, fatty acids, fatty acid esters, quaternary ammonium compounds and polymeric compounds. In the remaining 10 MNMs no organic compounds were detected by MS, despite the fact an organic coating was indicated by TGA.
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