An electronic technique is used for identifying a fluid and determining its level in a container. Specifically, impedance spectroscopy is applied to fluid handling probes such as those employed by automated chemical and immunoassay analyzers to provide superior sensitivity for fluid level detection as well as discernible "spectral signatures" (impedance spectra) that can be automatically analyzed to identify diverse materials. These include, but are not limited to, blood serum, blood plasma, gelsep, red blood cell layers, chemical reagents associated with immunoassay blood testing and foam atop fluid surfaces. In operation, incident electronic signal is compared with a reflected electronic signal to obtain signal characteristics that can be used to identify the type of liquid. In addition, characteristics of the reflected electronic signal (e.g., phase shift, etc.) as compared with the incident electronic signal are used to determine the level of fluid in a container.