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The use of synthetic chemicals in acid‒base testing has raised concerns about their environmental impact. The use of natural materials to produce natural indicator paper is an attempt to reduce the negative impact on the environment. Binahong (Anredera cordifolia) seeds can replace conventional chemical synthetic materials. This study aims to develop Binahong seed indicator paper as an alternative environmentally friendly material for acid‒base testing. The method used in this research is experimental and involves the extraction of Binahong seeds, making indicator paper with a certain formulation, and testing the performance of the indicator paper using standard acid and base solutions. Data collection was performed via the observation and measurement of certain parameters. The test results of the Binahong natural indicator paper revealed a significant color change when 95% ethanol was used, which produces a red or purple color at pH 1‒7, a blue color at pH 8‒10 and a yellow color at pH 11‒14. Binahong seeds have potential as an environmentally friendly alternative in acid‒base testing because they respond well to variations in the acidity and basicity of the solution.

Kaempferia galanga L. rhizomes contain ethyl trans-p-methoxycinnamate as a major secondary metabolite compound and biomarker. Various extraction methods with different solvents can isolate ethyl trans-p-methoxycinnamate with potential bioactivities. This paper reported the isolation of ethyl trans-p-methoxycinnamate from two varieties of K. galanga L. rhizomes by maceration in n-hexane. The small and large varieties of K. galanga samples produced ethyl trans-p-methoxycinnamate in 1.43% and 1.84% yields, higher than other methods and polar solvents of previous research. Structural elucidation of the obtained ethyl trans-p-methoxycinnamate was performed by FTIR, MS, and 1H NMR spectroscopies.

Mercury is a dangerous and toxic metal, thus necessitating an analytical method to ascertain its presence. Traditional methods for mercury analysis often involve costly instruments and specialized expertise. However, the Digital Image Colorimetry (DIC) method is an alternative for mercury detection due to its speed, simplicity, and cost-effectiveness. This research aims to synthesize silver nanoparticles (AgNPs) using Kepundung fruit peel (Baccaurea racemosa) extract as a mercury detector. Baccaurea racemosa has secondary metabolite compounds that can act as natural reducing agents (bioreductors) in synthesizing silver into nanoparticles. AgNPs were optimized and characterized using UV-Vis spectrophotometer, FTIR, PSA, and XRD instruments. Mercury detection was explained using RGB Detector and ImageJ. The research results revealed that the optimal conditions for synthesizing AgNPs involved a concentration of 1% extract and a pH of 7. The properties of the AgNPs included a maximum absorption at wavelengths of 400-450 nm, an average particle size of 122.7 nm, a face-centered cubic crystal structure, and characteristic functional groups at wavenumbers of 3453 cm-1, 1700-1600 cm-1, and 1445 cm-1. These spectral features suggested the presence of phytochemical compounds serving as bioreductants. Optimal results for mercury detection were achieved using Whatman paper no. 41 at pH 7. Mercury was detected successfully, whereas Pb2+, Na+, Mg2+, K+, Cu2+, Ca2+, Co2+, Zn2+, and Fe3+ ions were not detected. The validation test obtained a LoD of 0.099 ppm, a LoQ of 0.330 ppm, and a coefficient value (R2) of 0.997, indicating good measurement linearity. Further research can be developed to increase the sensitivity of mercury detection with lower concentrations and extend its application to environmental samples.