Colorimetric determination of total phenolic contents in ionic liquid extracts by paper microzones and digital camera

Abstract

In recent years, there has been a growing interest in the extraction of phenolic compounds from plants by using ionic liquid (IL) solutions. In this study, a colorimetric paper microzone assay was developed to analyse total phenolic contents in five imidazolium based IL solutions with concentrations 50-100 mM. Nine herb methanol extracts and two herb IL extracts were used for validation. The method validation parameters were as follows: the linear range for gallic acid and catechin in BMImAc, EMMImSO 4 , BMImCl, BMImBF 4 and C 12 MImCl aqueous solutions was between 0.25 and 2 mM, with the exception of catechin in a C 12 MImCl aqueous solution where it remained between 0.25 and 1.5 mM. LOD and LOQ values were determined for gallic acid and catechin IL solutions, whose IL structure and concentration were varied.In cases of all ionic liquids the determined LOD and LOQ values remained between 0.08-0.15 mM and 0.16-0.28 mM, respectively. The method was successfully validated against UV-Vis spectroscopy.

Fast Analysis of Total Polyphenol Content and Antioxidant Activity in Wines and Oenological Tannins Using a Flow Injection System with Tandem Diode Array and Electrochemical Detections

“…The flow injection method coupled with DAD-ECD detection was calibrated for both TPC and AA measurements using gallic acid as a standard (Table 1); validation showed satisfactory limit of quantification (LOQ = 0.012 mM (DAD); 0.005 mM (ECD)) that were suitable for the TPC and AA values expected in the oenological samples. The quantification showed good agreement and a slight improvement with respect to previous alternative analytical methods developed to quantify polyphenols, which exhibited LOQ values ranging from 0.006 to 0.25 mM for the gallic acid standard (Arce et al 1998;Gòmez-Alonso et al 2007;Aid et al 2015) and compared to the differential pulsed voltammetry method for the determination of antioxidant activity, which showed a LOQ of 0.006 mM in Catechin Equivalent, CE (Šeruga et al 2011). Results also showed improved performances according to LOQ calculated for the Folin-Ciocalteu method to determine the TPC (LOQ = 0.013 mM GAE) and DPPH method to determine the AA (LOQ = 0.037 mM Trolox Equivalent, TE), both related to the microplates assays (Bobo-García et al 2014).…”

Fighting COVID-19: Integrated Micro- and Nanosystems for Viral Infection Diagnostics

“…To simplify the system operation and enable highly sensitive molecular detection platforms for POC diagnostics, microfluidic systems that integrate the solid-phase-based NA extraction, amplification, and detection into a single reaction chamber were recently designed and adopted by existing LionX platforms. 43,44,[64][65][66][67] In addition, microfluidic paper-based analytical devices (mPADs) [68][69][70][71][72][73] represent another promising Perspective platform suitable for POC diagnostics that could successfully integrate the main processing steps involved in infectious disease diagnosis. 59,[74][75][76][77][78]…”

An Overview of Optical and Electrochemical Sensors and Biosensors for Analysis of Antioxidants in Food during the Last 5 Years

“…The formation of deposits of mixtures of the polyoxometalate-imidazole ionic liquid stopped the spectrophotometric diagnosis of analytes. The linear range and LOD were 0.25–2 mM and 0.08 mM, respectively [ 55 ]. For identification of whole polyphenol content of coffee samples, an interesting approach was proposed.…”