Flow injection chemiluminescent determination of clenbuterol using GoldMag particles as carrier

A novel flow injection chemiluminescent (CL) enzyme immunoassay for clenbuterol analysis based on GoldMag particles is described. GoldMag is a new type of super-paramagnetic Fe₃O₄/Au composite particle used as a carrier in a flow injection CL system. Clenbuterol conjugated with ovalbumin (OVA) was immobilized onto GoldMag particles and the particles fixed in a micro-channel by an external electromagnetic field. The clenbuterol test sample and clenbuterol polyclonal antibody (Ab) were injected into the channel and incubated with GoldMag particles. Clenbuterol, immobilized on the magnetic particle surfaces, competes for polyclonal antibodies with clenbuterol in the test sample. The free Ab or Ab combined with the clenbuterol sample was washed away and the magnetic particles conjugated with Ag-Ab left in the micro-channel. Horseradish peroxidase (HRP)-labelled goat anti-rabbit immunoglobulin G (IgG) was added and reacted with clenbuterol polyclonal antibodies; excess goat anti-rabbit-HRP was then washed off. When chemiluminescent reagents were injected into the channel, emitted light from the magnetic particle surface was measured and recorded using a photomultiplier-based apparatus. The linear range of this novel method was 0.01-0.1 ng g^-1 and recovery of clenbuterol was 85-105% with a RSD of 3.2% (n = 11).