Immunoassay automation equipment

Most of these assays can be performed using the same automated equipment that is used for plasma, but the assays will need to be validated separately for urine to ensure that the matrix (urine versus plasma) does not interfere with the method and that the enzyme levels present in urine, either endogenously or following injury, are within the limits of linearity. Immunoassays (ELISA) are commercially available for a, tt or i -glutathione-S-transferase in the rat and human (Biotrin International, Dublin). 

The separate items of equipment necessary for the preliminary (i.e. sample preparation) stages of partially automated (i.e. prior to the final measurement instrument) immunoassay available from Denby Instruments Ltd are listed in Appendix 1. 

This author and coworkers at Beckman Coulter first described the use of a low form 96-well plastic microplate for automated micro-ELISA immunoassays (Matson et al., 2001). The polypropylene plate was first modified by a radiofrequency plasma amination process (Matson et al., 1995) followed by conversion to an acyl fluoride surface chemistry for rapid covalent attachment of biomolecules. Proteins (1 to 2 mg/mL) were prepared in 50 mM carbonate buffer, pH 9, containing 4% sodium sulfate (to improve spot uniformity) and printed using a conventional arrayer system. Approximately 200-pL droplets of monoclonal antibodies (anti-cytokine) were deposited into the bottom of the microwells using a Cartesian PS7200 system equipped... 

Cost Effectiveness. As with the other advantages of immunochemical analysis, cost may be quite variable. Reagent costs for several automated systems have been estimated at under 1.25 per sample. The cost is obviously much lower for less sophisticated assay systems, especially if some reagents are prepared in house. A major consideration is the expense of new instrumentation. For dedicated or automated instrumentation for either RIA or ELISA procedures, the cost may be 50-100,000. However, most analytical laboratories already have the basic instrumentation needed for immunoassays. Moderate sensitivity can be obtained through the use of numerous procedures such as radial immunodiffusion and hemagglutination. These procedures require no expensive equipment or reagents and they may be very useful in areas where equipment acquisition or maintenance is a problem. 

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