Application of dual-step potential on single screen-printed modified carbon paste electrodes for detection of amino acids and proteins

A novel screen-printed biosensor for protein and amino acid (AA) estimation is reported. A rhodinised carbon paste working electrode (WE) was used in. the three-electrode configuration. Bromine was generated by the electrolys is of an acidic potassium bromide electrolyte on the working electrode when poised at an appropriate potential. The consumption of bromine by the prot ein and amino acid was then measured at a lower-potential. This sensor was used to detect most of the amino acids and some common proteins. The method is highly sensitive and can even detect L- and D- proline which give no re sponse with enzyme electrodes. This sensor has also been used to detect pro tein/amino acid in fruit juice, milk, and urine. The unique feature of the sensor is that it does not require any reagent/chemical other than buffer. No surface treatment or modification of the WE is necessary and hence the s ensor is stable for the lifetime of the basic screen-printed electrode, whi ch is about a year. A very small amount of analyte (10 mu L) is required fo r direct detection. The sensor is inexpensive and disposable and may also b e used for continuous-flow systems. This sensor may have useful application in process monitoring and control during the production of amino acids.