Specific Rotation of Aqueous Dextrose and Sucrose Under the Influence of Amino Acids Glycine and L-alanin Using LED Polarimeter

Abstract

The sugar industry produces wastewater high in organic content that typically must be treated before it is discharged into streams or municipal sewer systems. Sugars and amino acids play an important role in cellular metabolism and thus flooding an environment with excess cellular fuel can result in increased bacteria in rivers and streams as well as oxygen depleted dead zones in marine environments. A quick and inexpensive approach to the detection of simple sugars in water would be helpful in localizing and identifying sources of excess sugars in the environment. Polarimetry is potentially one option to detect sugars since most sugars are optically active. Unfortunately, organic compounds can interact with the sugar and greatly alter the polarimetry. This work studies the effect of amino acids such as glycine and L-alanine on the optical rotation of aqueous dextrose and sucrose. The optical activity of dextrose and sucrose solutions were measured in the presence of the amino acids glycine, and L-alanine, by a single wavelength LED polarimeter. The optical rotation was recorded in terms of absolute rotation and thereafter converted to specific rotation taking the solution concentration into consideration. It also has been observed that the pH of the solution mixtures was very minimally influenced by amino acid interaction with sugar solution demonstrating that there has been no major reaction between molecules within the solution. Glycine and L-alanine are optically inactive and optically active amino acids respectively. Experimental results showed that they decrease the specific rotation of sugar solutions. This research indicates that the interactions of amino acids with sugars in solution significantly impacts the specific rotation of the optically active sugars. Therefore, to use polarimetry to detect concentrations of sugar in water, it is important to consider the interaction of other organic compounds such as amino acids that may also be present in the streams.