Sensitive determination of tannic acid using blue luminescent graphene quantum dots as fluorophore
2016
Sinduja, Bharathi | John, S Abraham
The present study describes the sensitive and selective determination of tannic acid (TA) using graphene quantum dots (GQDs) as fluorophore. The GQDs were prepared by pyrolysis of citric acid and were characterised by HR-TEM analysis, UV-visible spectroscopy and spectrofluorimetry. The prepared GQDs were blue luminescence and show absorbance and emission maxima at 361 and 453 nm, respectively. While adding 1 μM of TA to GQDs, the absorption band at 361 nm was blue shifted to 325 nm with increase in intensity. After the addition of 25 μM TA to GQDs, the colourless solution of GQDs becomes yellow colour. On the other hand, the emission intensity of GQDs at 453 nm was decreased even in the presence of 0.1 μM TA. The GQDs show good selectivity towards the determination of TA in the presence of 100-fold excess of common interferents including glucose, oxalate and ascorbic acid. The good linearity was observed for the emission intensity against 0.1 × 10⁻⁶ to 1 × 10⁻⁶ M TA and the detection limit was found to be 2.6 × 10⁻⁸ M (S/N = 3). The present method was successfully applied to determine TA in beer samples and the results were validated with HPLC.
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