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Abstract: In this paper we propose a specific sandwich immunoassay method for human-immunoglobulin G (HIgG). This immunoassay protocol takes advantage of sandwich binding of primary and secondary antibodies for increased specificity. Polystyrene microspheres (PS) serve as immobilizing support, site for sandwich immunoassay and then subsequently used for chemiluminescence (CL) detections. In this sandwich immunoassay, PS microspheres were modified with the primary anti-HIgG (Ab1) via electrostatic interaction, while CdTe nanoparticles (CdTeNPs) were modified with horseradish peroxidase labeled anti-HIgG (Ab2) via covalent binding. Antigen HIgG (Ag) was specifically captured by the first and secondary antibody and form sandwich immunoassay format. Combination of the remarkable sensitivity of CL method and the use of CdTe NPs as anti-HIgG–HRP carrier for the enzymatic signal amplification, provide a linear response range of HIgG from 0.01 to 300ngmL−1 with an extremely low detection limit of 0.3pgmL−1. This immunoassay system has many desirable merits including sensitivity, accuracy, and little required instrumentation. The assay results were compared with enzyme-linked immunosorbent assay (ELISA), and showed relatively good reliability. Significantly the new protocol may become quite promising technique for protein immune-detection as well as DNA analysis and other biological analyses. [Copyright &y& Elsevier]

Abstract: A highly sensitive flow-injection chemiluminescent method for the direct determination of pyrogallol compounds has been developed. Proposed method is based on the enhanced effect of pyrogallol compounds on the chemiluminescence signals of KMnO4–H2O2 system in slightly alkaline medium. Three important pyrogallol compounds, pyrogallic acid, gallic acid and tannic acid, have been detected by this method, and the possible mechanism of the CL reaction is also discussed. The proposed method is simple, convenient, rapid (60samplesh−1), and sensitive, has a linear range of 8×10−10 molL−1 to 1×10−5 molL−1, for pyrogallic acid, with a detection limit of 6×10−11 molL−1, 4×10−8 molL−1 to 5×10−3 molL−1 for gallic acid with a detection limit of 9×10−10 molL−1, and 8×10−8 molL−1 to 5×10−2 molL−1 for tannic acid, with a detection limit of 2×10−9 molL−1, respectively. The relative standard deviation (RSD, n =15) was 0.8, 1.1 and 1.3% for 5×10−6 molL−1 pyrogallic acid, gallic acid and tannic acid, respectively. The proposed method was successfully applied to the determination of pyrogallol compounds in tea and coffee samples. [Copyright &y& Elsevier]