Finally, polarization measurements can be performed completely under external control by adding an Autopolarization Assembly. This is a stepper-motor-driven polarizer mount that may be positioned in the excitation beam to rotate the polarizer between the H and V orientations under computer control. The host computer records the ratios IVV/IVH and IHV/IHH, then calculates either polarization or anisotropy, depending on the operators the antibody, as shown by the dashed curve in Fig-choice of ACQUISITION MODE.
The concentration of theophylline in serum or plasma is monitored by fluorescence polarization immunoassay. Theophylline (Figure 3) is a drug administered for myocardial stimulation, increased coronary blood flow, and smooth-muscle relaxation. It can be a bronchodilator in the control of asthma, for example. The observed fluorescence polarization of a fluorescein-labeled theophylline tracer is inversely related to the drug concentration. The drug level in a given sample therefore can be determined by comparison with a calibration curve.
A pre-treatment solution, the theophylline standard in a pH-7.2 buffer, the theophylline-fluorescein tracer, and antiserum were mixed together and incubated for three minutes before determining the fluorescence polarization. The theophylline samples were from General Diagnostics; Abbot Laboratories supplied the standards and other reagents.
Polarization measurements were performed on a SPEX FLUOROLOG spectrofluorometer consisting of three single-grating spectrometers, the T-format Sampling Module, a T-format Polarization Kit, the Autopolarization Assembly, and two Hamamatsu R928P detectors. A 450-W xenon lamp supplied the excitation.
Results and Discussion