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Screening and Optimization Consortium Technique of the Bacillus megatherium and Saccharomyces cerevisiae Microbial Consortium for Ethanol Detection Nurdiani Nurdiani; Dyah Iswantini; Novik Nurhidayat; Wulan Tri Wahyuni; Agus Kartono
Jurnal Kimia Valensi Jurnal Kimia VALENSI Volume 9, No. 1, May 2023
Publisher : Syarif Hidayatullah State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v9i1.31506

Determination of alcohol content is very important in the food and beverage industry. Biosensor is an alternative to measuring ethanol content. Alcohol biosensors with a single microbe still have a narrow measurement area at ethanol concentrations, so a microbial consortium is needed to widen the range of measured ethanol concentrations. Therefore, it is necessary to screen the microbes from Bacillus sp and S. cerevisiae which have the potential to produce alcohol dehydrogenase (ADH) enzymes and optimize the consortium technique that can provide the best response to oxidation currents. In the yeast microbial screening of 14 S. cerevisiae isolates and 5 Bacillus sp isolates, it can be concluded that for the 14 yeast S. cerevisiae isolates that have the potential to produce ADH enzymes, there is one isolate with the SCRF code. For the 5 bacterial isolates of Bacillus sp that have the potential to produce ADH enzymes, all Bacillus isolates with the code Bacillus megatherium 29/9/14, Bacillus megatherium 23/6/22, Bacillus 6, Bacillus 53, and Bacillus 55. Based on the oxidation current data, Bacillus megatherium 23 /6/22 produces the highest current compared to other Bacillus isolates. The consortium technique that provides the highest current is the method of mixing 1:1 (µL) microbial suspension in an Eppendorf container. Optimization of the consortium's biofilms using the Response Surface Method was produced at 10 days of age, pH 7.5, and 75 µL of microbial suspension dripping volume.

Nonenzymatic Sensor Based on Glassy Carbon Electrode Modified by Platinum Nanoparticles Decorated Reduced Graphene Oxide for Glucose Detection in Human Urine Nisa, Ulfiatun; Iswantini, Dyah; Ahmad, Shahrul Nizam; Mahat, Mohd Muzamir; Putra, Budi Riza; Saskito, Dinda Iryawati Bedy; Wahyuni, Wulan Tri
Jurnal Kimia Valensi Jurnal Kimia VALENSI, Volume 10, No. 2, November 2024
Publisher : Syarif Hidayatullah State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v10i2.40035

This research aims to develop a sensitive and selective nonenzymatic electrochemical sensor for glucose detection using a glassy carbon electrode modified with platinum nanoparticles (PtNPs) decorated on reduced graphene oxide (RGO). The structural properties and surface morphology of PtNPs/RGO composite were characterized using Raman spectroscopy and scanning electron microscopy (SEM). In addition, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed to investigate glucose measurements in human urine samples. The developed sensor shows an increasing anodic peak of glucose with a linear response at a concentration range from 10 to 1000 µM, with a detection limit of 5 µM. The proposed sensor also demonstrated good reproducibility, indicated by the value of relative standard deviation (%RSD) of 3.9%, and maintained its current response over seven consecutive measurements. Moreover, the proposed sensor exhibited high selectivity for glucose detection against several potential interferences, such as potassium (K+), chloride (Cl−), magnesium (Mg2+), ascorbic acid, dopamine, and urea, with recovery values of 96-102%, which are acceptable within the analytical range. Furthermore, this proposed sensor successfully detected glucose in human urine samples, and their concentrations were not significantly different when measured with a commercial glucose sensor.

Development of a Low-Cost Reflectance Visible Spectrophotometer with Chemometrics for Curcuma xanthorrhiza Roxb. Quality Control Heryanto, Rudi; Iswantini, Dyah; Rohaeti, Eti; Rafi, Mohamad; Rahma, Novia; Hafshah, Nurul; Mardiana, Eni
Jurnal Kimia Valensi Jurnal Kimia VALENSI, Volume 10, No. 2, November 2024
Publisher : Syarif Hidayatullah State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v10i2.40351

A simple, portable visible reflectance spectrophotometer was developed for classifying the quality of Curcuma xanthorrhiza Roxb. The device was assembled using consumer electronic components: an LED as the light source, a DVD optical layer as the diffraction grating, and a webcam as the detector, with web-based software (Spectral Workbench) as the signal processor. The spectrophotometer's performance was evaluated using standard Sudan III samples and powdered C. xanthorrhiza samples from two quality classes (A and B). Spectral data were analysed using principal component analysis (PCA) and partial least squares (PLS) regression. PCA successfully grouped Sudan III samples by concentration and classified C. xanthorrhiza by curcuminoid content. A PLS regression model was developed for quantifying Sudan III, yielding R² values of 0.9909 for both calibration and cross-validation, with RMSEs of 0.3821% and 0.4152%, respectively. The results closely matched those from a commercial spectrophotometer. A PLS-discriminant analysis (PLS-DA) classification model for C. xanthorrhiza was also developed, achieving sensitivity and specificity values of 1. Additionally, semi-quantitative parameters such as decision limit (26.15% B), detection capability (41.06% B), and unreliability range (26.15–41.06% B) were calculated. The classification model showed strong sensitivity, specificity, and detection capabilities within acceptable limits. These findings suggest that this low-cost reflectance spectrophotometer, combined with chemometric methods, holds promise as a practical tool for the quality control of raw herbal materials.

Nonenzymatic Sensor Based on Glassy Carbon Electrode Modified by Platinum Nanoparticles Decorated Reduced Graphene Oxide for Glucose Detection in Human Urine Nisa, Ulfiatun; Iswantini, Dyah; Ahmad, Shahrul Nizam; Mahat, Mohd Muzamir; Putra, Budi Riza; Saskito, Dinda Iryawati Bedy; Wahyuni, Wulan Tri
Jurnal Kimia Valensi Jurnal Kimia VALENSI, Volume 10, No. 2, November 2024
Publisher : Department of Chemistry, Faculty of Science and Technology Syarif Hidayatullah Jakarta State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v10i2.40035

This research aims to develop a sensitive and selective nonenzymatic electrochemical sensor for glucose detection using a glassy carbon electrode modified with platinum nanoparticles (PtNPs) decorated on reduced graphene oxide (RGO). The structural properties and surface morphology of PtNPs/RGO composite were characterized using Raman spectroscopy and scanning electron microscopy (SEM). In addition, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed to investigate glucose measurements in human urine samples. The developed sensor shows an increasing anodic peak of glucose with a linear response at a concentration range from 10 to 1000 µM, with a detection limit of 5 µM. The proposed sensor also demonstrated good reproducibility, indicated by the value of relative standard deviation (%RSD) of 3.9%, and maintained its current response over seven consecutive measurements. Moreover, the proposed sensor exhibited high selectivity for glucose detection against several potential interferences, such as potassium (K+), chloride (Cl−), magnesium (Mg2+), ascorbic acid, dopamine, and urea, with recovery values of 96-102%, which are acceptable within the analytical range. Furthermore, this proposed sensor successfully detected glucose in human urine samples, and their concentrations were not significantly different when measured with a commercial glucose sensor.

Development of a Low-Cost Reflectance Visible Spectrophotometer with Chemometrics for Curcuma xanthorrhiza Roxb. Quality Control Heryanto, Rudi; Iswantini, Dyah; Rohaeti, Eti; Rafi, Mohamad; Rahma, Novia; Hafshah, Nurul; Mardiana, Eni
Jurnal Kimia Valensi Jurnal Kimia VALENSI, Volume 10, No. 2, November 2024
Publisher : Department of Chemistry, Faculty of Science and Technology Syarif Hidayatullah Jakarta State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v10i2.40351

A simple, portable visible reflectance spectrophotometer was developed for classifying the quality of Curcuma xanthorrhiza Roxb. The device was assembled using consumer electronic components: an LED as the light source, a DVD optical layer as the diffraction grating, and a webcam as the detector, with web-based software (Spectral Workbench) as the signal processor. The spectrophotometer's performance was evaluated using standard Sudan III samples and powdered C. xanthorrhiza samples from two quality classes (A and B). Spectral data were analysed using principal component analysis (PCA) and partial least squares (PLS) regression. PCA successfully grouped Sudan III samples by concentration and classified C. xanthorrhiza by curcuminoid content. A PLS regression model was developed for quantifying Sudan III, yielding R² values of 0.9909 for both calibration and cross-validation, with RMSEs of 0.3821% and 0.4152%, respectively. The results closely matched those from a commercial spectrophotometer. A PLS-discriminant analysis (PLS-DA) classification model for C. xanthorrhiza was also developed, achieving sensitivity and specificity values of 1. Additionally, semi-quantitative parameters such as decision limit (26.15% B), detection capability (41.06% B), and unreliability range (26.15–41.06% B) were calculated. The classification model showed strong sensitivity, specificity, and detection capabilities within acceptable limits. These findings suggest that this low-cost reflectance spectrophotometer, combined with chemometric methods, holds promise as a practical tool for the quality control of raw herbal materials.

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