Nonionic surfactants mass spectrometry

Zhu, J. (2004). Liquid chromatography-mass spectrometry of nonionic surfactants using electrospray ionization. J. Surfactants Detergents 7(4), 421 -23. 

Rivera, J., Carxach, S., Ventura, F. et al. FAB-CAD-MIKES. Analysis of nonionic surfactant in raw sewage sludges, (ed J.F.F.Todd), Proceedings of the 10th International Mass Spectrometry Conference, Swansea September 9-13 1985, J.Wiley, Basingstoke, UK (1985). 

Petrovic M, Barcelo D. 2000. Determination of anionic and nonionic surfactants, their degradation products, and endocrine-disrupting compounds in sewage sludge by liquid chromatograpy/mass spectrometry. Anal Chem 72 4560-4567. 

Figure 29-9 illustrates a separation of the oligomers in a sample of the nonionic surfactant Triton X-100, Detection involved measuring the total ion current produced by chemical ioni/.aiion mass spectrometry. The mobile phase was carbon dioxide containing 1 % by volume of methanol. The column was a 30-m capillary column coated with a 1-pm lilm of 5% phenylpolysi-loxane. The column pressure was increased linearly at a rate of 2,5 bar/min. 

The same relates to the analytical methods, where for anionic, nonionic and cationic surfactants, various colorimetric procedures (MBAS, bismuth active substance(s) (BiAS), and disulfine blue active substance(s) (DSBAS)) were introduced. Since these methods analyse only the loss of surface-activity or primary degradation, other analytical approaches have been employed in the last 10 years in order to characterize the total or ultimate degradation. These include methods such as high performance liquid chromatography (HPLC), gas chromatography (GC) GC/mass spectrometry (MS), and the measurement of total organic carbon (TOC) and chemical oxygen demand (COD). 

Hyphenation between GC or LC and mass spectrometry (MS) has improved these techniques, however the high cost of the equipment limits its use in routine quality control. GC-MS has been used to determine different analytes in cosmetics (e.g., essential oils). LC-MS has also been used (e.g., ceramides, cationic and nonionic surfactants, preservatives). 

Trier, X., Granby, K., and Christensen, J. H. 2011. Tools to discover anionic and nonionic polyfluorinated alkyl surfactants by hquid chromatography elechospray ionisation mass spectrometry. J. Chromatogr. A 1218 7094-7104. 

For most volatile or gaseous species more selectivity may be achieved by combining mass spectrometry with gas chromatography. This is applicable to some nonionic surfactants [1] and derivatives of anionics [2]. The combination of gas chromatography with mass spectrometry (GC-MS) is well established, and relatively cheap dedicated instruments are available for this application. 

Harvey, G. J. and Dunphy, J. C. Characterisation of cationic, anionic, and nonionic surfactants by positive and negative ion electrospray ionization mass spectrometry. Proceedings of the 40th ASMS Conference on Mass Spectrometry and Allied Topics, Washington, DC, May 31-June 5, 1992. 

As a separation technique, GC is inherently more powerful than HPLC however, it is limited by the volatility of the compounds to be analyzed. For this reason only nonionic surfactants with low degrees of ethoxylation are amenable to direct determination using GC. High-molecular nonionic surfactants as well as ionic surfactants must be derivatized prior to GC analysis in order to transform them into more volatile compounds. Apart from the flame ionization detector (FID), mass spectrometry (MS) is increasingly becoming the dominant determination method for surfactants in enviromnental matrices. MS is not only a very sensitive and selective detection method but also provides valuable information on the molecular weight and structure of separated compounds (Table 24.6). 

Levine, L.H. Garland, J.L. Johnson, J.V. HPLC/ESI-Quadrapole Ion Trap Mass Spectrometry for Characterization and Direct Quantification of Amphoteric and Nonionic Surfactants in Aqueous Samples. Anal. Chem. 2002, 74, 2064-2071. 

Barco, M. Planas, C. Palacios, O. Ventura, F. Rivera, J. Caixach, J. Simultaneous Quantitative Analysis of Anionic, Cationic, and Nonionic Surfactants in Water by Electrospray Ionization Mass Spectrometry with Flow Injection Analysis. Anal. Chem. 2003, 75,5179-5136. 

---