The Anagen system for automated fluorometric immunoassay.

We describe a new discrete microprocessor-controlled analyzer, the AN2000, which fully automates fluorometric immunoassays by using a magnetic separation of the solid phase and an alkaline phosphatase label. It can operate in random-access or batch mode with a dwell time typically less than 20 min. The analysis rate is 75 samples per hour and the system can hold refrigerated reagents for as many as 20 different analytes. The substrate and wash buffer are common to all analytes. The system can hold as many as 80 samples at once. The operator can select from the menu-driven operator interface any combination of the available analytes to be run for each sample, using either the touch screen or the keyboard. Results are calculated from a stored calibration curve that is stable for greater than or equal to 1 month. The AN2000 is capable of automating most assay formats because the available timings, volumes, incubations, and wash cycles can be used in any combination.

Bioelectrochemical immunoassay for human chorionic gonadotrophin in serum using an electrode-immobilised capture antibody.

An amperometric technique for the quantification of an enzyme immunoassay which utilises a capture antibody covalently attached to a carbon electrode is described. The electrode is used both to separate the assay and to monitor the activity of the bound enzyme label. A 'two-site' immunometric assay with monoclonal antibodies directed against human chorionic gonadotrophin (HCG) was used as the model system. The activity of the enzyme bound to the electrode is determined electrochemically by the use of an electron transfer mediator (dimethylaminomethyl ferrocene) permitting rapid quantification of the analyte without the need for a separate incubation step to measure enzyme activity. The sensitivity of the assay is 9mIU HCG ml-1 in serum (1st International Reference Preparation). The correlation between the amperometric measurement of serum HCG and data for an immunoradiometric assay was r = 0.988. The assay is rapid requiring a total assay time of 20 min per sample, which includes 15 min for antibody-antigen binding.

Bioelectrochemical enzyme immunoassay of human choriogonadotropin with magnetic electrodes.

We describe an amperometric technique for quantification of an enzyme immunoassay in which we use a magnetic working electrode, both to separate bound and free analyte and to monitor the electrochemical response. We used a "two-site" immunometric assay with monoclonal antibodies for human choriogonadotropin (hCG) as a model system in which magnetic particles were used as the solid phase. Separation of bound and free label is readily achieved by localizing the particles at the electrode. Activity of the bound enzyme in the environment of the electrode is determined electrochemically, permitting rapid quantification of the analyte without the need for a separate incubation step to measure enzyme activity. The sensitivity of the system is 150 int. units of hCG per litre (1st Int. Ref. Preparation). Correlation between the amperometric measurement of urinary hCG and data for an immunoradiometric assay was r = 0.9. The assay is rapid, requiring a total assay time for each sample of 20 min, which includes 15 min for antibody/antigen binding.

New separation method for monoclonal immunoradiometric assays and its application to assays for thyrotropin and human choriogonadotropin.

We describe a novel separation procedure for immunoradiometric assays involving monoclonal antibodies in which both radiolabeled and capture antibodies are used in solution, the capture antibody being labeled with fluorescein isothiocyanate (FITC). Separation is achieved by incubation with anti-FITC antibodies on magnetic particles. This technique enhances reaction kinetics relative to those of assays in which a solid-phase capture antibody is used, thus allowing faster reaction times and more economic use of the monoclonal antibodies. The use of anti-FITC magnetic solid phase produces an assay having a highly specific separation method, minimal nonspecific binding, and high sensitivity. The method is illustrated by application to assays for thyrotropin and human choriogonadotropin.