Application of¹³C NMR to the identification of surfactants in mixture

Abstract

The possibility of using the 13C NMR technique as a preliminary screening for the analysis of manufactured household products is presented. Spectra for several surfactants and related products in water solution were obtained for reference. The application of 13C NMR to commercial products shows that many surfactants can easily be distinguished from one another and determined from a single spectrum without laborious separative pretreatments.The complete analysis of commercial detergents is becoming more and more difficult as the complexity of formulations increases. Nowadays, a wide :range of manufactured products usually consists of different ionic and nonionic surfactants and a variety of other organic and inorganic constituents. Complete]y identifying the various components of a modern detergent product can be a very complex task. As a rule, it is necessary to effect separation. The analysis procedures most commonly used are extraction procedures, followed by column chromatography and then by chemical analyses of the various fractions (1-3). None of these procedures, however, is uniformly applicable, and it may be necessary sometimes to proceed by trial aad error, at the expense of time. The procedure which the analyst will adopt depends upon whether the presence of certain surfactants is known or unknown. In other words, a better organized approach to the analysis can certainly be planned if one can have advance information on the nature of the mixture of surfactants presertt in the product under examination. This kind of information, in addition, may be all that is required. In specific market surveys a complete analysis of the cowponents may not be necessary, but the combination of the various surfactants must be continuously and rapidly checked.The application of instrumental methods could furnish an answer to this problem. However, the function of instrumental methods usually has been for identification after qualitative separations have been achieved. Chromatographic techniques, such as TLC and HPLC, certainly have been used to determine surfactants in commercial detergents {4-6). These technique:s are not always suitable for quantitative analysis though. They often require a long time to optimize conditions of analysis and cannot be applied indifferently for any detergent.In the present work the possibility of using 13C FT NMR as a useful analytical tool in the field of detergency is considered.We are routinely applying this technique a/iready as a preliminary screening for the analysis of manufactured products. The high resolution of the technique, by contrast with other instrumental methods, allows one to get useful information without any laborious separation, working directly with the commercial product, if liquid, or simply with an ethanol extract, if powder. One can determine rapidly {usually no more than ca. three hr of repetitive scans) not only the nature of the surfactant mixture, but also useful information on structure and on the presence of other organic and inorganic constituents. Of course...

Composition analysis of two batches of polysorbate 60 using MS and NMR techniques

“…Thus, understanding Tween 60 chemical composition would help formulators not only in forecasting properties of Tween 60 emulsified products but also in choosing Tween 60 concentrations to achieve desired applications. In the past, although the possibility of using NMR techniques as useful analytical tool in the field of polyoxyethylene-type substances was considered [5][6][7], the NMR exploitation in analyzing structure of polysorbate emulsifiers is still limited quantitatively and qualitatively. For instance, 1 H spectra of Tween 20 only picked up NMR signals arising from the sorbitan skeleton, lauric acid tail and polyoxyethylene protons, respectively [7].…”

Rapid and Simple Identification and Quantification of Components in Detergent Formulations by Nuclear Magnetic Resonance Spectroscopy

“…However, there are very few reports on the application of NMR for studying commercial detergent formulations. In research dating 30–40 years back, a few references describe the application of 13 C NMR for identification of surfactants (Carminati et al, ; Kalinoski and Jensen, ; Kosugi et al, ), whereas more recent publications seem to focus on diffusion and behavior of surfactants and micelles (Griffith et al, ; Hologne et al, ; McLachlan et al, ; Nicolle et al, ; Soderman et al, ). In addition, Visser et al described the specific analysis of polycarboxylate polymers in detergents using liquid extraction, followed by size‐exclusion chromatography ‐ nuclear magnetic resonance (Visser et al, ), and Fournial et al have reported the NMR‐based characterization of commercial nonionic surfactants (Fournial et al, ).…”

New validation of molecular mass measurements by means of 2D DOSY 1H NMR experiments: Application to surfactants

“…The integration of 1 H NMR spectra gave the average value of the alkyl chain length and polyethoxylated part in the case of non-ionic surfactants. 13 C NMR assignment of anionic, cationic and non-ionic surfactants were proposed by Carminati et al [3] as a preliminary screening for the analysis of manufactured products. Fournial et al [4] proposed a 1 H and 13 C study of This study proposes a new correlation equation between surfactant diffusion coefficients and molecular mass using 2D DOSY 1 H NMR experiment.…”