Surfactants, analysis

The first two aspects entail relatively high concentrations of surfactants. In the last case, trace amounts are to be determined. When performing surfactant analysis, preconcentration and/or separation of the different surfactant classes are prerequisites for identifying and quantifying the compound in question. Furthermore, the trend is to analyze the individual components of any surfactant mixture. 

After the first use of ion-selective electrodes in surfactant analysis in 1957... 

It is important that any method for surfactant analysis maintains the same oligomer distribution in the extracted samples. LLE and SPE are generally combined with chromatographic methods for separation and resolution of non-ionic surfactants into their ethoxamers. An alternative is the use of SPME-HPLC, recently reported by Chen and Pawliszyn [141]. Alkylphenol ethoxylate surfactants such as Triton X-100 and various Rexol grades in water were determined by means of SPME-NPLC-UV (at 220 nm) [142]. Detection limits for individual alkylphenol ethoxamers were at low ppb level. 

D.C. Cullum (ed.), Introduction to Surfactant Analysis, Blackie, Glasgow (1994). 

D.O. Hummel, Handbook of Surfactant Analysis, John Wiley Sons, Ltd, Chichester (1999). 

Industrial applications of MDLC are discussed in Chapters 17 and 18. These chapters embody the types of applications used in polymer and surfactant analysis that have become mainstream in the MDLC literature. 

The mechanisms of the first- and second-dimension separations are independent here that is, the alkyl chain length separation is independent of the PEO chain length. The retention in this case is often called orthogonal between the two dimensions. A discussion of orthogonal separations is given in Chapters 2, 3, 6, and 12. This independent nature of the two separation dimensions allows the full analysis of the alkyl and PEO components per molecule. Additional examples of the independence in separation axes will further demonstrate the importance of 2DLC for surfactant analysis. 

Parris, N. (1978). Surfactant analysis by high performance liquid chromatography I. A rapid analysis for mixtures of amphoteric surfactants and soap. J. Am. Oil Chem. Soc. 55(9), 675-677. 

Petrovic, M., Barcelo, D. (2003). Capillary electrophoresis in surfactant analysis. Comprehensive Anal. Chem. 40, 77-87. 

The sample pretreatment steps for surfactant analysis such as extraction and concentration can be carried out in a variety of ways. Most of the common and well tested procedures have been described by Schmitt [46]. Solid phase extraction (SPE) with C2, Cg or Cis and divinyl benzene resins as well as special phases, e.g. graphitised carbon black (GCB), can be adequate methods, especially for SPE of metabolites from... 

SAMPLING AND SAMPLE TREATMENT FOR SURFACTANT ANALYSIS IN WATER... 

Pretreatment of biological samples for surfactant analysis is usually straightforward and includes either homogenising with anhydrous sodium sulphate or freeze-drying. Below, the sample treatment methods for extraction and clean-up of non-ionic and anionic surfactants in biota that have been encountered in the literature are reviewed. 

Stability of calibrants and analytes is another frequently overlooked aspect of quality assurance, which is particularly relevant to surfactants. This aspect is discussed in Chapter 4.4. Very few intercalibration studies have been performed for the surfactant types of analytes (cf. Chapter 4.5). Currently, no certified reference material is available for surfactants. The European Commission has recently tendered for production of a reference material with certified surfactant concentrations [2]. We can conclude that quality assurance in quantitative surfactant analysis is still in its infancy when compared to analysis of PCB or chlorinated dioxins. Notwithstanding this, several important achievements have been made during recent years regarding improvement of the accuracy and reliability of qualitative analysis of surfactants, which will be the subject of the following chapters. 

After equilibrium, at 25 1 0.1°C, for = 24 h the serum was collected for surfactant analysis by filtering the latex through a... 

Another dynamic factor affecting the rate of diffusion transfer, mentioned long ago by Gibbs [9], is the elasticity of the surfactant monolayers which decreases the capillary pressure in small bubbles during their compression and increases it in large bubbles during their expansion. This effect is most pronounced in bubbles whose adsorption layers contain insoluble surfactants. Analysis of the influence of this factor on diffusion transfer has been reported in [486], However, no experimental verification has been performed so far. 

Successfully developing a surface engineering strategy based on surfactant behavior at interfaces requires surface characterization techniques that can validate and quantify surface chemistry changes. This review describes the role of two surface chemistry analysis techniques that have proven highly successful in surfactant analysis x-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SSIMS). In Section II, the methods by which these techniques analyze surface chemistry are described. In Section III, recent examples of their application in surfactant-based surface engineering are described. 

Commercial surfactants contain mixtures of isomers and homologs and may also contain variable amounts of unreacted starting material or extraneous oil that is added as a diluent or thinning agent. Variable amounts of water and inorganic salts are usually present in these products. In order to maintain quality assurance, considerable effort must be put in the development of accurate quantitative techniques for the characterization of components present in these surfactants. Several publications and reviews are available that describe techniques developed for surfactant analysis [1-6]. 

Institute of Surfactants Analysis (ed.). Analysis of Surfactants, Saiwai Shobo, Japan, 1980. 

Only the apphcation of LC-MS analysis can be conceived of as reliable surfactant analysis. To elaborate determination methods for the analysis of the anionic surfactant mixture of alkyl ethoxysuUates (AES) APCI and ESI-MS(-t/-) studies combined with in-source MS/MS examinations were performed and results were compared (cf. Pig. 15.4 and 15.5 and 15.3.3.2 ESI, surfactants). APCI fragment ion spectra revealed the aUcyl chain length and the number of ethoxylate moieties therefore APCI was found to be the method of choice [326]. To confirm determination methods apphed in surfactant analyses an inter-laboratory comparison study of LC-MS techniques and enzyme-hnked immunosorbent assay for the determination of surfactants in wastewaters was performed in seven laboratories. The quantitative determination of the non-ionic NPEOs, AEOs, coconut diethanol amides (CDEAs) and the anionic LAS, NPEO-sulfates and the secondary alkane sulfonates (SAS) was performed under APCI or ESI-interfacing conditions in positive or negative... 

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