Martin Sulistyani
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Optimization of Microplate Type Uv-vis  Spectrophotometer Performance as an Antioxidant Activity Testing Instrument Martin Sulistyani; F. Widhi Mahatmanti; Nuril Huda; Ridho Prasetyo
Indonesian Journal of Chemical Science Vol. 13 No. 1 (2024)
Publisher : Prodi Kimia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/ijcs.v13i1.5014

Abstract

Eliminating a compound's capacity to impede and neutralize free radical-induced oxidation processes is the goal of antioxidant activity analysis. The DPPH (pikrilhidrazil-2,2-difenil-1) method was the approach taken in this investigation. Simple, sensitive, stable, quick, straightforward, and suitable for usage with tiny sample volumes are some of the benefits of DPPH procedures. In this investigation, some plant extracts were employed as a comparison, with ascorbic acid serving as the control. In order to evaluate a microplate-type uv-vis  Spectrophotometer effectiveness as an antioxidant activity test tool, the study will determine its maximum wave, linearity, accuracy, and IC50 values. Wavelength selectivity is found in 517 nm. The results validation of the DPPH method for analyzing the activity of antioxidants. Measurements of the ascorbic acid solution as a control obtained R2 values of 0.9781 compared to the LoD and LoQ limits of 0.961 and 3.053 respectively. The IC50 of ascorbic acid, ginger and turmeric, respectively, was 14.7218 (strong), 29.9194 (very strong), and 52.4943 (strong). 
Optimization of the Performance of a Microplate Type UV-Vis Spectrophotometer as a Protein Content Testing Instrument Based on Green Analytical Chemistry (GAC) Martin Sulistyani; Mahatmanti, F. Widhi; Huda, Nuril; Prasetyo, Ridho
Indonesian Journal of Chemical Science Vol. 14 No. 3 (2025): Indonesian Journal of Chemical Science
Publisher : Prodi Kimia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/ijcs.v14i3.31948

Abstract

Advancements in laboratory technology have driven the adoption of more efficient and environmentally friendly analytical methods, in line with the principles of Green Analytical Chemistry (GAC). This study aims to optimize the performance of a microplate-based UV-Vis spectrophotometer for determining protein content in food samples using the Biuret method. The method is based on a colorimetric reaction between Biuret reagent and peptide bonds in proteins, forming a purple complex whose absorbance is proportional to protein concentration. Three dilution methods were evaluated: mL-microplate, µL-microplate, and mL-cuvette, based on parameters including maximum wavelength, linearity, and accuracy. All methods showed the same maximum absorbance wavelength (562 nm), indicating reaction stability. The mL-cuvette method achieved the highest linearity (R² = 0.998), while the mL-microplate method demonstrated the best accuracy (91.00%) and most consistent results in tempeh and yogurt samples. Meanwhile, the µL-microplate method offered acceptable accuracy (90.25%) with significantly reduced reagent volume, supporting the GAC approach. Therefore, the mL-microplate method is recommended as the primary technique for protein analysis using UV-Vis spectrophotometry, while the µL-microplate method provides an efficient and eco-friendly alternative for modern laboratory applications.