Neumann , X. Wang , R. Niessner and D. E-mail: dietmar. Herein we describe the development of a homogeneous competitive colorimetric immunoassay using antigen-functionalized magnetic beads MBs and antibody-immobilized gold nanoparticles AuNPs combined with the established gold staining method for the determination of microcystin-leucine-arginine MC-LR in surface water. Solid phase extraction proved to be the most beneficial sample preparation method in order to reduce matrix effects which might lead to agglomeration of the AuNPs and failing of the assay.
The developed method could detect MC-LR in a linear range from 0. The recovery rates of the toxin in spiked water samples were in the range from To date, the most widespread methods for the identification and quantification of MCs in water samples are based on HPLC coupled to different detection methods like mass spectrometry MS , 5,6 fluorescence FL 7 and ultraviolet UV spectroscopy.
Consequently, the development of rapid and cost-effective methods is needed. In the past, an enzyme-linked immunosorbent assay ELISA based on the interaction between antigen and antibody for the detection of MC-LR was established in our institute and yielded an IC 50 value of 0. Gold nanoparticles AuNPs , for example, are used for rapid colorimetric assays because they own a lot of advantages like facile preparation, unique catalytic property and simplicity in modification.
Depending on the complexity of the sample, dilution is required to eliminate interfering matrix effects. In this work, solid phase extraction SPE was combined with the competitive colorimetric immunoassay for the determination of low concentrations of MC-LR in lake and river water. These particles are stable for approximately 3 months. Fifty microliters of MC10E7 solution 1. The resulting supernatant was removed and the nanoparticles were resuspended in washing solution phosphate buffer, 0. The ESI was operated in negative ionization mode.
It was operated at resolution of 50 2 Hz and the maximum injection time was Spray voltage was set at 2. MC-LR was identified by its retention time of 8. The mechanism of this enlargement of the AuNPs was recently published by our group and it was demonstrated that the sensitivity can be improved significantly. An experiment was conducted where different PBS concentrations were tested.
