Fluorescence polarization immunoassays (FPIAs) were developed for potato glycoalkaloids (GAB) using a polyclonal antiserum and a monoclonal antibody (MAb). Fluorescently labeled solanidine (AMF-SOL) was synthesized by coupling 4'-(aminomethyl)fluorescein (4'-AMF) to the hemisuccinate derivative of solanidine using an active ester method. Both polyclonal antibody (PAL) and MAb could quantify the major potato GAs in the 20 - 100 nM range; however, the affinities of PAb and MAb differed slightly among the individual GAs. PAb displayed the greatest affinity for alpha-chaconine, while MAb was more sensitive to changes in alpha-solanine levels. Affinity constants (Kaff) of PAb and MAb for AMF-SOL were estimated at 4.2 X 10(8) and 4.7 10(7) M-1, respectively. Potato samples containing low, medium, and high levels of GAs were successfully analyzed by the PAb FPIA. Equilibrium in the FPIA reaction was reached within 1-2 min, and standard curves were stable for at least 14 days.