A flow immunoassay for alkylphenol ethoxylate surfactants and their metabolites—questions associated with cross-reactivity, matrix effects, and validation by chromatographic techniques

Abstract

This paper describes the application and evaluation of a competitive enzyme flow injection immunoassay (EFIIA) for screening of alkylphenol ethoxylate (APEO) surfactants in different water samples based on a generic immunoassay system previously developed (see E. Burestedt, C Nistor, U. Schagerlöf and J. Emnéus, Anal. Chem., 2000, 72, 4171-4177). The detection limits for octylphenol ethoxylates (OPEOs), nonylphenol ethoxylates (NPEOs), and nonylphenol (NP) were 0.5 µg l 21 , between 2 and 3 µg l 21 , and 50 µg l 21 , respectively, with a sample throughput of 6 h 21 (i.e., for triplicate analysis of each sample). Different OPEOs and NPEOs were highly cross-reactive within the assay, with sensitivities in the same order of magnitude for all the ethoxylates tested, thus the result obtained by the EFIIA method could be used as an "alkylphenol ethoxylate index". No or minor matrix effects with recoveries between 70-120% for the reference analyte NPEO 10 in tap, and surface water, and acceptable for rainwater, were observed. Influent and effluent surfactant containing wastewater samples were analysed by EFIIA, LC-MS, LC-Fluoresence (LC-FL), and a commercial microplate ELISA. High recoveries for different concentrations of APEO 10 spiked into a 200 times diluted raw influent and effluent wastewater were achieved with the EFIIA method, however, the found APEO content of the same diluted wastewater samples, before spiking, could not be correlated directly to the chromatographic result by any of the immunoassays, and the possible reasons for this are discussed. The same trend of decreasing APEO content from influent to effluent wastewater could, however, be followed for all methods employed. † Electronic supplementary information (ESI) available: Cross reactivity data. See http://www.rsc.org/suppdata/an/b3/b302110f/ Fig. 1 General structure of APEOs (a), APs (b), and the chemical structure of the APEO hapten derivative used for tracer synthesis in this work (c). R denotes the alkyl chain, i.e., octyl-or nonyl-groups; n: 1-40 ethoxy groups. This journal is

Analysis of Nonylphenol: Advances and Improvements in the Immunochemical Determination Using Antibodies Raised against the Technical Mixture and Hydrophilic Immunoreagents

“…At present, we do not have solid arguments to explain this recognition pattern, although we suspect that the reason could be related to the particular physical properties of the NP and its ethoxylate counterparts (solubility in aqueous media, possibility to form micelles and aggregates, etc.). In fact, a high degree of recognition of NPEO in most of the ELISAs previously reported (20,22) has been observed, even if the immunizing hapten keeps the hydroxyl group free. Thus, as mentioned before, in the ELISA recently developed by Mart'ianov et al (36) all the NPEO were highly recognized (NP1EO, NP2EO, NP(9-10)EO, and NP1EC with CR values of 188%, 279%, and 79%, and 48% respectively).…”

“…The hydrophobicity of the molecule (log Pow 4.48, ref 17) determines its low water solubility (5 mg L -1 ) and the tendency of this substance to adsorb to the solid surfaces (i.e., plasticware). Despite the immunochemical techniques developed for NP (ELISAs (14)(15)(16)18), dipstick assays (19), polarization fluoroimmunoassays (20,21), flow injection immunoassays (22), and capillary immunoassays ( 23)), this issue has never been seriously addressed.…”

Removal of nonylphenol ethoxylate from laundry wastewater using modified and functionalized activated carbon

“…This is mainly due to their remarkable characteristics, such as relative ionic insensitivity and high absorptive behaviour. 1 APEOs are comprised of a hydrophobic phenol ring with varied alkyl chains and a hydrophilic chain with 1-100 ethoxylated groups (EO). Around 80% of APEOs represent nonylphenol ethoxylates (NPEO), and the remaining is octylphenol ethoxylates (OPEO).…”

Aflatoxin M1 determination in raw milk using a flow-injection immunoassay system

“…We adapted a generic flow-injection immunoassay (FI-IA) system initially developed for atrazine as a model compound [19]. This was then adapted and applied with very good results for triazine herbicides [20] and alkyl phenol ethoxylate surfactants determination in waste water [21].…”