Sequential injection chemiluminescence immunoassay for nonionic surfactants by using magnetic microbeads

• Published in: Analytica chimica acta Vol. 600; no. 1; pp. 105 - 113
• Main Authors: Zhang, RuiQi, Nakajima, Hizuru, Soh, Nobuaki, Nakano, Koji, Masadome, Takashi, Nagata, Kazumi, Sakamoto, Kazuhira, Imato, Toshihiko
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 26.09.2007; Elsevier
• Subjects: Analytical chemistry; Animals; Antibodies - immunology; Calibration; Chemical and thermal methods; Chemiluminescence; Chemistry; Computer Simulation; Exact sciences and technology; Flow Injection Analysis - instrumentation; Flow Injection Analysis - methods; Fresh Water - analysis; Horseradish Peroxidase - metabolism; Immunoassay; Immunoassay - instrumentation; Immunoassay - methods; Luminescent Measurements - instrumentation; Luminescent Measurements - methods; Magnetic microbeads; Magnetics; Mice; Microspheres; Miscellaneous; Molecular Structure; Nonionic surfactants; Rivers - chemistry; Sequential injection analysis; Surface-Active Agents - chemistry; Immunoassay; Sequential injection analysis; Nonionic surfactants; Chemiluminescence; Magnetic microbeads; Hydrogen peroxide; Neodymium; Immobilization; Standard; Monoclonal antibody; Immunological method; Magnetic material; Sequential method; Detection limit; Luminol; Standard curve; Peroxidase; Time analysis; Flow injection; Microsphere; Photon counting; Enzyme; Non ionic surfactant; Ultratrace compound; Switching; Trapping; Peroxidases; Sample cell; Carboxylate; Oxidoreductases; River water
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2007.02.052

A rapid and sensitive immunoassay based on a sequential injection analysis (SIA) using magnetic microbeads for the determination of alkylphenol polyethoxylates (APnEOs) is described. An SIA system was constructed from a syringe pump, a switching valve, a flow-through type immunoreaction cell equipped with a photon counting unit and a neodymium magnet. Magnetic beads, to which an anti-APnEOs monoclonal antibody was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of the magnetic beads in and from the immunoreaction cell were controlled by means of a neodymium magnet and adjusting the flow of a carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an anti-APnEOs monoclonal antibody immobilized on the magnetic beads with a sample APnEOs and a horseradish peroxidase (HRP)-labeled APnEOs in the same sample solution, and was based on the subsequent chemiluminscence reaction of HRP on the magnetic microbeads with a luminol solution containing hydrogen peroxide and p-iodophenol. The anti-APnEOs antibody was immobilized on the magnetic microbeads by coupling the antibody with the magnetic beads after activation of a carboxylate moiety on the surface of the magnetic beads that had been coated with a polylactic acid film. The antibody immobilized magnetic beads were introduced in the immunoreaction cell and trapped in it by the neodymium magnet, which was equipped beneath the immunoreaction cell. An APnEOs sample solution containing the HRP-labeled APnEOs at a constant concentration, and a luminol solution containing hydrogen peroxide and p-iodophenol were sequentially introduced into the immunoreaction cell, according to an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photon counting unit located at the upper side of the immunoreaction cell by collecting the emitted light with a lens. A typical sigmoidal calibration curve was obtained, when the logarithm of the concentration of APnEOs was plotted against the chemiluminescence intensity as the number of photons in 100 ms using standard APnEOs sample solutions at various concentrations (0–1000 ppb) under optimum conditions. The lower detection limit defined as IC 80 is ca 10 ppb. The time required for analysis is less than 15 min per a sample. The present method was successfully applied to the determination of APnEOs in river water.