A Micro Benedict’s assay for the Determination of Glucose

The determination of glucose by Benedict's solution is a staple activity in Biotechnology  labs.  The classic format is to set up a large-scale reaction (5-10 ml) in glass tubes and boil until the desired reaction occurs. In the education lab this is a slow procedure and potentially fraught with problems.  Benedicts solution contains alkali and large volume boiling alkali solutions in an open tube are always a potential hazard.  Here, we suggest a micro procedure that can be done in a standard heating  block. 

Reactions are assembled in Eppendorf centrifuge tubes.  The unknown sample is Q’d to 250ul. Benedicts (250uL) is added and the tubes are closed (lid locks can be used if needed) and are heated at 70 degrees centigrade in a thermal block. Color development is monitored (usually takes 5-10 minutes) by negative and positive controls and the presence of glucose in the unknown determined.

In an inquiry driven exercise  this   rapid method is useful since it permits many determinations  of glucose in even a short lab session.

Here is an example from a recent  Inquiry exercise.