Analytical Methods 2018-04-10

Exploring MBTH as spectrophotometric probe for total phenolic compounds determination in beverage samples

Bruna da Silva Granja, José Ricardo Honório de Mendonça Filho, Woodland de Souza Oliveira, Josue Carinhanha

Index: 10.1039/C8AY00464A

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Abstract

In this work, we propose an alternative method using MBTH (3-methyl-2-benzothiazolinone hydrazine) as spectrophotometric probe for the determination of total phenolic compounds. The method is based on oxidative coupling reaction of MBTH with phenolic compounds in acidic medium to generate a colored product. In optimum conditions the oxidizing Fe(III) was prepared in H2SO4. The sensitivity of the MBTH method was compared with the Folin-Ciocalteau (FC) method against 17 phenolic compounds. Samples of wines (red and white), coffees (instant and brewed), teas and infusions were analyzed by proposed method and the results were compared with the FC and 4-AAP (total phenolic compounds) besides ABTS•+ and DPPH• (antioxidant capacity) methods. The results were submitted to a linear correlation analysis for a range of 95% confidence, between MBTH and FC (r = 0.9665); MBTH and 4-AAP (r = 0.8425); MBTH and DPPH• (r = 0.9667) and MBTH and ABTS•+ (r = 0.9670). A more detailed analysis was performed according to the different samples classes and we observed that the results of MBTH method were more consistent with DPPH• and ABTS•+ with the other methods. Thus, the spectrophotometric method developed was characterized as simple, feasible for the samples analyzed and with results comparable to the usual assays.