Flow immunoassay for nonioinic surfactants based on surface plasmon resonance sensors

Mayumi Tanaka, Kazuhira Sakamoto, Hizuru Nakajima, Nobuaki Soh, Koji Nakano, Takashi Masadome, Toshihiko Imato

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

A rapid, sensitive immunoassay based on a surface plasmon resonance sensor in a flow system for the determination of alkylphenol polyethoxylate (APEO) is described. The method is based on an indirect competitive reaction between an anti-APEO antibody in the sample solution and APEO immobilized on a sensor chip and APEO in the same sample solution. A sensor chip was prepared by immobilizing an APEO-horseradish peroxidase (APEO-HRP) conjugate on the thin gold film of the sensor chip. The adsorption constants for the APEO-HRP conjugate on the sensor chip and the surface density of the APEO-HRP adsorbed on the sensor chip at the saturated state were estimated to be 4.7 × 10 5 M -1 and 5.0 × 10 -14 mol/mm 2 , respectively, using a Langmuir adsorption isotherm equation and results from the adsorption experiments. The affinity constants for the immunocomplexes of the anti-APEO antibody with the APEO conjugate on the sensor chip and for APEO in the sample solution were estimated to 2.0 × 10 6 and 5.1 × 10 6 M -1 , respectively. A typical sigmoid calibration curve for APEO was obtained in the concentration range from 1 ppb to 1000 ppb. The detection limit, defined as the concentration of APEO, at which 85% of the sensor signal was observed, was ca. 10 ppb. The assay was applied to the determination of APEO in tap water in conjunction with a solid phase extraction pretreatment; APEO levels of approximately 50 ppt were successfully determined. 2009

Original languageEnglish
Pages (from-to)999-1005
Number of pages7
JournalAnalytical Sciences
Volume25
Issue number8
DOIs
Publication statusPublished - 2009 Aug

ASJC Scopus subject areas

  • Analytical Chemistry

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