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Eco-friendly pectin/BCG film sensor: a smartphone-compatible platform for gamma-aminobutyric acid detection
(2026-05-01)
Niamlaoong, Rungthiwa
;
Teerasong, Saowapak
;
Phengdaam, Apichat
;
Tantirungrotechai, Yuthana
;
Wattanasin, Panwadee
This work introduces a biodegradable pectin–bromocresol green (BCG) film integrated into a microplate platform for the colorimetric determination of gamma-aminobutyric acid (GABA). The sensing mechanism relies on electrostatic ion-pair formation between the protonated amine group of GABA (-NH₃+) and the sulfonate group of BCG, producing a distinct color transition from yellow to green. The resulting colorimetric response was quantitatively analyzed using a smartphone-assisted RGB system coupled with ImageJ software. Molecular modelling provided insight into the interaction mechanism and indicated that the GABA-BCG association is dominated by electrostatic interactions. Under optimized conditions, the developed assay exhibited a wide linear range (0.1–1000 mg L−1) with detection and quantification limits of 0.07 mg L−1 and 0.22 mg L−1, respectively. Good analytical precision was achieved (%RSD ≤ 5%), while negligible interference from common amino acids, vitamins and food additives was observed. The method was successfully applied to beverage and dietary supplement samples, demonstrating good agreement with HPLC analysis. The biodegradable BCG–pectin film platform provides a rapid, low-cost, and portable approach for GABA determination and represents a promising sensing strategy aligned with the principles of green analytical chemistry.
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Sequential injection for determination of gamma-aminobutyric acid based on its effect on second order light scattering of silver nanoparticles
(2016-08-01)
Jinnarak, Amornrassamee
;
Anantavichian, Pattarapon
;
Intanin, Apichai
;
Fungladda, Suchada
;
Choengchan, Nathawut
An automated sequential injection (SI) with second order light scattering (SOS) detection for determination of gamma-aminobutyric acid (GABA) was developed. Quantitation is based on electrostatic interaction between GABA and citrate-capped silver nanoparticles (AgNPs). In acetate buffer at pH 3.8, the positively charged GABA induces the nanoparticles to aggregate. This results in a change of light scattering monitored using a spectrofluorometer. In this work, working standard solutions of GABA were prepared in-line by the SI system pumping appropriate volumes of a stock solution of GABA and acetate buffer into a holding coil. Solution of AgNPs was subsequently drawn into the coil. The reaction zone was then transferred to the spectrofluorometer, set with excitation and detection wavelengths at 300 and 600 nm, respectively. Under optimised condition, the SOS intensity was proportional to the concentration of GABA. As a result, a linear curve was obtained in the range of 100–400 mg L−1 GABA, with a lower limit of detection of 39.6 mg L‐1. Good precision of analysis was achieved, with 0.6 and 3.3% relative standard deviation (RSD) for external calibration (n = 5) and standard addition (n = 3), respectively. The developed method was successfully applied for quantification of GABA in dietary supplements (2 samples) and samples of instant green tea (2 samples).
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A novel colorimetric method for detection of gamma-aminobutyric acid based on silver nanoparticles
(2016-06-28)
Jinnarak, Amornrassamee
;
Teerasong, Saowapak
A novel, simple and rapid colorimetric method for determination of gamma-aminobutyric acid (GABA) was developed using a negatively charged citrate-capped silver nanoparticle (AgNP) probe. At an acidic pH of 3.8, GABA had a positive charge due to a protonation of amine groups. Therefore GABA could induce an aggregation of AgNPs due to electrostatic interaction. This caused a decrease in the surface plasmon resonance spectra of the colloidal solution at wavelength of 390 nm with a slight red shift. At the same time, the color of the suspension turned from yellow to green upon aggregation. Quantification of GABA was done spectrophotometrically. Under optimum conditions, the method showed a linear calibration in range of 100-500 mg L-1 GABA, with a detection limit of 57.7 mg L-1. The method was successfully applied to measure GABA quantities in dietary supplements.

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