Indonesian Chimica Letters

Development of Arduino Uno Based Multispectra Colorimeter For Formaldehyde Determination

2025-06-16T13:51:14+07:00

Formalin is a hazardous substance that is often misused as a food preservative, so routine formalin analysis is very necessary for public safety. Formalin analysis generally uses spectrophotometry and also a simple colorimeter. Currently, many Arduino-based colorimeters are being studied and development with RGB (Red, Green, Blue) LED (Light Emitting Diode) light sources. This research is also in this field with a focus on the use of multi-spectral RGB LED lights with 16 colors that are already commercially available. The multispectral colorimeter is designed by integrating an LED light source, a photodiode module as a detector, and controlled by an Arduino Uno R3. The LED light module circuit, cuvette and detector photodiode are then arranged and packaged in an X8 project box. Optimization of the circuit is studied including the distance between the LED lamp and the cuvette and the photodiode with the cuvette. A feasibility study of the use of multispectral RGB LEDs is also carried out by looking at the stability of the response of each color. The performance test of the multispectral colorimeter is carried out by analyzing formaldehyde oxidized with hydrogen peroxide using methyl red as an indicator under the alkaline condition. The results showed no significant difference when viewed from the linearity, Limit of Detection, Limit of Quantitation, sensitivity, and precision values calculated from the calibration curve. The difference in linearity values was 0.0013, Limit of Detection = 0.17, Limit of Quantitation = 0.57, sensitivity = 0.0001, and precision (SD = 0.001 and %RSD = 0.11).

The Volatile Compound Profiles of Fire-Cured and Fermented Na-Oogst Tobacco Leaves (Nicotiana tabacum L.) and Its In-Silico Study

2025-06-16T18:34:16+07:00

Na-Oogst tobacco is one of the local commodities of Jember, which has been widely used as a raw material for making cigarettes. Product diversification in processing tobacco leaves is very necessary to reduce the danger caused by cigarette consumption. It is also an effort to empower and save the economy of tobacco farmers. Tobacco leaf’ essential oil could be an alternative in maintaining tobacco production. The purpose of this study is to determine the profile (yield and chemical compounds) of Na-Oogst tobacco leaf essential oil content in pre- and post-fermentation. Extraction of essential oils is carried out by two methods, i.e., steam distillation and maceration. The results showed that the extraction from the maceration method produced higher yields than from steam distillation, while the extract from tobacco leaves before fermentation was lower than that after fermentation. The major identified compounds found in tobacco leaves from GC-MS analysis are neophytadiene, nicotine, ledol, phytol, and solanone. Neophytadiene is suggested as a marker compound in tobacco leaf since it is present in all extracts and essential oils in significant amounts, about 23.72-67.37% of the total identified compounds. Further molecular docking of neophytadiene against the D2 dopamine receptor is also investigated in this study.

The Effect of Concentrated Seawater Salinity on Soybean Protein Coagulation in Tofu Production

2025-06-11T09:35:10+07:00

Seawater, which has a salinity of 35 ‰, contains essential ions such as chloride, sodium, sulfate, magnesium, and calcium. These ions play a crucial role in the coagulation of proteins. Salt-based coagulants are among the oldest and most commonly used in tofu production. Additionally, several metal cations exhibit similar coagulating effects on soybean proteins. Tofu can be produced by adding salt coagulants, like calcium sulfate (commonly known as tofu stone) and seawater extract. The seawater extract was obtained from seawater through evaporation in three distinct ponds, with varying evaporation times that can lead to differences in salinity and density. In this experiment, we used coagulants from these three ponds, labeled A, B, and C. Coagulant C, derived from the pond with the longest evaporation time, has the highest salinity of 310 ‰ and a density of 1.220 g/cm³. The mass of the tofu produced shows a consistent pattern among coagulants A, B, and C: an initial increase followed by a decrease, which is influenced by the salting-out and salting-in processes. When used at a volume of 15 mL, Coagulant C yielded the highest mass at 179.426 grams and the lowest water content at 71.152%, demonstrating its effectiveness in protein coagulation.

Deployment Pattern of Lead (Pb) in Jenggawah Area, Jember, East Java

2025-06-16T15:10:41+07:00

The damaging effects of lead (Pb) contamination in soil has been significant public health concern, mainly due to its toxicity. Jenggawah district, located in Jember regency, Indonesia, has experienced growing anthropogenic activity in recent years, leading to the necessity to map the prevalence of this dangerous element in this area. Therefore, this research aims to evaluate the spatial and vertical distribution of lead (Pb) contamination level in the soil of the Jenggawah area. The soil samples were collected using random sampling techniques from seven different locations at various distances from the roadside (0, 25 m, and 50 m) and different depths (0, 15 cm, and 30 cm). Then, the soil sample containing lead (Pb) content were extracted through an acid-based destruction and quantified using Atomic Absorption Spectrophotometry. This study explained that lead (Pb) concentrations in all soil samples from the Jenggawah area were below established thresholds (1 - 8 ppm) and consistently reduced with increasing soil depth. Additionally, the variation of lead content in terms of distance from the roadside revealed a more fluctuating pattern, possibly affected by ground surface conditions and wind factors. In conclusion, these results can provide environmental information and enhance the understanding of heavy metal risks in areas with moderate anthropogenic activity, such as Jenggawah.