title: Sequential injection chemiluminescence immunoassay for anionic surfactants using magnetic microbeads immobilized with an antibody.
abstract: A rapid and sensitive immunoassay for the determination of linear alkylbenzene sulfonates (LAS) is described. The method involves a sequential injection analysis (SIA) system equipped with a chemiluminescence detector and a neodymium magnet. Magnetic beads, to which an anti-LAS monoclonal antibody was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of the magnetic beads in the flow cell were controlled by means of a neodymium magnet and adjusting the flow of the carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an anti-LAS monoclonal antibody on the magnetic beads and the LAS sample and horseradish peroxidase (HRP)-labeled LAS, and was based on the subsequent chemiluminscence reaction of HRP with hydrogen peroxide and p-iodophenol, in a luminol solution. The anti-LAS antibody was immobilized on the beads by coupling the antibody with the magnetic beads after activation of a carboxylate moiety on the surface of magnetic beads that had been coated with a polylactic acid film. The antibody immobilized magnetic beads were introduced, and trapped in the flow cell equipped with the neodymium magnet, an LAS solution containing HRP-labeled LAS at constant concentration and the luminol solution were sequentially introduced into the flow cell based on an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photon counting unit located at the upper side of the flow cell by collecting the emitted light with a lens. A typical sigmoid calibration curve was obtained, when the logarithm of the concentration of LAS was plotted against the chemiluminescence intensity using various concentrations of standard LAS samples (0-500ppb) under optimum conditions. The time required for analysis is less than 15min.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Kyushu University Hakozaki, Fukuoka 812-8581, Japan.
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Zhang
authors.forename: Koji
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Seto
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Soh
authors.forename: Koji
authors.initials: K
authors.lastname: Nakano
authors.forename: Takashi
authors.initials: T
authors.lastname: Masadome
authors.forename: Kazumi
authors.initials: K
authors.lastname: Nagata
authors.forename: Kazuhira
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Imato