Molecular distribution of some commercial nonylphenol ethoxylates using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Abstract

Nonylphenol ethoxylates (NPEs) belong to a group of nonionic surfactants that are collectively referred to as alkylphenol ethoxylates (APEs). APEs find widespread use in heavy-duty commercial and household cleaning formulations, shampoos, and industrial processing, i.e. textile manufacture. Their environmental impact depends on the molecular distribution and the extent of their biodegradation in municipal sewage systems, waterways and rivers. We have established two sample preparation methods that have enabled the determination of the molecular distributions of six commercial nonylphenol ethoxylates using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). In both methods, alpha-cyano-4-hydroxycinnamic acid, dissolved in acetonitrile/tetrahydrofuran, was used as the matrix. In one set of experiments, the NPEs were dissolved in an acetonitrile/tetrahydrofuran solvent system prior to mixing with the matrix solution, and the resulting MALDI-TOF mass spectra produced mostly sodiated molecules [M + Na](+). The NPEs, all having the formula 4-(C(9)H(19))-C(6)H(4)-(OCH(2)CH(2))(n)-OH, are Surfonic (R)N-95, N-100, N-102, N-120, N-150 and N-300. Surfonic N-95 and N-100 gave n values of 5-20; Surfonic N-102, N-120, N-150, and N-300 gave n values of 5-21, 5-22, 8-25 and 15-40, respectively. In order to develop a sample preparation method that could be used with less polar NPEs, we dissolved the NPEs (except N-300) in pentane prior to mixing with the matrix solution, and found that the MALDI spectral quality was unaffected by the solvent systems. Copyright 1999 John Wiley & Sons, Ltd.

Small molecule analysis by MALDI mass spectrometry

“…Complex mixtures of PEGs, PEG esters, isosorbide polyethoxylate were detected, in fact seven different series of oligomers ions were present due to a mixture of fatty acid esters [65]. Nonylphenylethoxylate surfactants (Surfonic), which can serve as a carbon source/ substrate to produce polyhydroxybutyrate for bacterial degradation, have been investigated by this group [66]. Either a higher molecular weight (noninterfering) porphyrin matrix or α-CHCA was utilized as matrix for the Surfonic samples, although higher sample concentrations were necessary for the α-CHCA matrix.…”

Ion/Molecule Attachment Reactions: Mass Spectrometry

“…MALDI-MS, FAB-MS, and PDI-MS data for PEG-esters of (2-benzothiazolon-3-yl)acetic acid have been reported as well [281] as are data on PEGylated peptides and other (bio) molecules [282]. Similarly, [M + NH 4 ] + -and [M + Na] + -ions are frequently observed for PEG-esters of relatively nonpolar molecules, e.g., nonylphenol ethoxylates that are used as surfactants [283]. The characterization of various PEG polymers with different end groups, i.e., linear hydroxyl, amino, and/or alkyl, or cyclic crown ether end groups, using MS-MS based on FAB-MS-generated [M + Li] + -ions was also reported [284].…”

Modelling the fate of nonylphenolic compounds in the Seine River — part 1: Determination of in-situ attenuation rate constants

“…The biodegradation rate constants of 19 NPnEO have been mostly determined through bioreactor laboratory experiments (Staples et (closer to in-situ conditions) and found biodegradation rate constants ranging from 0.04 d -1 to 0.10 d -1 for NP 9 EO 26 and from 0.08 to 0.09 d -1 for 4-NP. The difficulty to assess the NPnEO concentrations and their biodegradation 27 relies in the fact that there is a lack of commercial pure reference standards which can be used for a reliable 28 analysis, and that various commercial mixtures exist with different chain lengths according to their use 1 (Ayorinde et al, 1999). 2 To date, only one study focuses on the determination of in-situ attenuation rate constants of NPnEO and 4-NP 3 based on a hydrodynamic and biogeochemical model (Jonkers et al, 2005).…”