简介:Immunochemical assays (immunoassays, IAs) are biochemical
assays which work according to the law of mass
action. They are based on the recognition of an antigen
(Ag) or a hapten by antibodies (Abs). Abs are serum
gly简介:Immunochemical assays (immunoassays, IAs) are biochemical
assays which work according to the law of mass
action. They are based on the recognition of an antigen
(Ag) or a hapten by antibodies (Abs). Abs are serum
glycoproteins of the immunoglobulin (Ig) class and are
produced by the vertebrate immune system against foreign
material of high molecular mass. The result of the binding
reaction between the Ab and an analyte is usually made
visible by means of enzymatic, chemiluminescent, fluorescent
or radioactive markers. According to the label used
IAs can be classified into enzyme immunoassays (EIAs),
radioimmunoassays (RIAs), fluorescence immunoassays
(FIAs) or chemiluminescent immunoassays (CLIAs). The
measuring range of most IAs for pesticides is in the parts per trillion to lower parts per billion range. A lot of samples
can be analyzed within a short time, while only low
sample volumes are necessary. In many cases (water, some
liquid food samples) no extraction step and no cleanup
are necessary. Not all assays are completely specific to one
single compound. Cross-reactivities of the Abs with haptens
similar to the analyte can be observed. In some cases,
matrix effects may occur, especially with soil or colored
food extracts. Therefore, validation of the assays for the
matrix of interest should be carried out. As IAs are usually
targeted at a single analyte or a group of analytes, multianalyte
approaches using Ab arrays or a combination of
immunochemical techniques with liquid chromatography
(LC) are pursued.详细>