Abstract
Riboflavin (Vitamin B2) is a well known vitamin and plays an important role in biological oxidation and reduction. It is important biochemically because it is vital for proper utilization of carbohydrates, fats, and proteins as energy sources. Therefore, selective and fast determination of this compound is important. As yet, there is not any report for costruction of DNA-biosensor for the determination of riboflavin. This project has two sections. In the first section we prepared a selective biosensor based on interaction of riboflavin at a salmon sperm ds-DNA–modified pencil graphite electrode (DNA–PGE) was introduced as a promising tool for determination of riboflavin, by differential pulse voltammetry. The mechanism of the interaction was at the PGE surface. The decrease in intensity of the guanine and adenine oxidation signals was used as an indicator for the sensitive determination of riboflavin. Under the optimum conditions, a linear dependence of the guanine and adenine oxidation signals was observed for the riboflavin concentration in the range of 0.5 – 70.0 μg mL–1 with a detection limit of 0.34 μg mL–1 at DNA–PGE. In the second part, preparation of electrochemically pretreated pencil graphite electrode (PPGE) and its application for the determination of riboflavin using differential pulse adsorptive stripping voltammetric (ASDPV) method was also investigated. Several important parameters were investigated and optimized to control the performance of the PPGE which showed a high selectivity and sensitivity toward riboflavin. A linear relationship was obtained for riboflavin over the concentration range of 0.003 to 0.88 μg mL–1 with a detection limit of 0.076 ng mL–1. The biosensor was applied and validated for the analysis of riboflavin in pharmaceutical and urine. The accuracy and precision were confirmed using t-test and F-test, respectively.