Immunochemical methods performance/limitations

The sensitivity of the overall analytical procedure depends upon many factors obviously including the type of sample to be analyzed and the skill of the analytical chemist. If an immunoassay is used to measure the amount of pesticide in a water sample by adding the water sample directly to the immunoassay, very high sensitivity may not be obtained although the assay will require very little time to perform. Alternatively, if the water sample is extracted and the immunoassay is employed only after several highly efficient cleanup steps, phenomenal sensitivity may be obtained at the expense of a large investment in time. In some situations, immunochemical methods may decrease the limit of detectability of a pesticide residue (77), but more importantly they may, in some cases, decrease the time and cost needed to reach a level of detectability as has been demonstrated with parathion (31). 

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