Our PKM-RE team from the Chemistry Study Program, Faculty of Mathematics and Natural Sciences, Jember University, has successfully received funding from the Ministry of Education and Culture, Research, and Technology. Our PKM-RE team, consisting of Lina Sun Haji as team leader and members Choirun Nisa Anida, Caleysda Aprilianti, Himayah Izmi Fauziyyah, and Diah Ayu Pitaloka, has carried a theme entitled Test strip Berbasis Metil Merah Untuk Tes Cepat, Praktis, dan Ekonomis Senyawa Formalin dalam Sampel Ikan atau dapat disebut dengan Trifommer (Test strip Formalin Berbasis Metil Merah). Our teamwork program is accompanied by Dr. . Zulfikar, Ph.D., who helps, supervises, and directs the smooth performance of teamwork.
Formalin can also be known as formaldehyde, which is a chemical compound that is often used as a preservative for corpses in the embalming process. Formalin can be used as a preservative for corpses because it helps prevent body decomposition due to the nature of formalin, which can stop the growth of bacteria and fungi. However, formalin is often misused when preserving food so that it does not rot quickly. One of the foods that is often preserved is fish. Formalin is a food that is strictly prohibited from being added to food because it can interfere with the performance of the body’s organs. Research conducted by Sari (2019) states that if formalin is consumed in the long term, it can damage the liver, kidneys, spleen, pancreas, and other organs in the body.
Therefore, it is necessary to have a method for formalin detection, especially in a short time. Our team developed a simple formalin analysis using formalin test strips. The formalin detection test using our methyl red-based test strip is intended to help test the presence of formaldehyde content in fish samples quickly, practically, and, of course, economically. In the formalin detection test, methyl red is used as an indicator to indicate the formaldehyde content in fish samples through color changes. Methyl red is an indicator or dye that will change color when a reaction occurs between the H2O2 reagent and formalin. Color changes can be observed in the test strip, which was originally yellow and turned red. The color change is due to the formation of formic acid from the reaction of formalin with the reagent.
Development is carried out in various stages, namely: sample extraction (fresh fish), making test strips, optimizing test strips, determining working range, applying test strips to fish samples validated with formalin test kits, and life-time testing. Extraction is carried out by soaking the fish sample in water so that the formalin dissolves in the water and then filtering it using filter paper to separate the solids from the filtrate. The test strip is made of two parts, namely the detection area made of Whatman paper and the handle made of acrylic. The test strip-making stage is carried out using Whatman paper cut into circles with a diameter of 1 cm, which functions as a detection area, and acrylic measuring 5×2 cm, which functions as a handle.
Optimizing the test strip begins with determining the immobilization time, the optimum composition volume of H2O2, NaOH, and methyl red, the amount of paper, and the type of Whatman paper used. The paper was then immobilized using a methyl red reagent and NaOH. The process of adding the reagent is carried out drop by drop, where Whatman paper is dipped into it and left for 40 minutes. The paper is then dried. The determination of the working range is based on the calibration curve from formalin analysis with H2O2 using UV-Vis spectrophotometry. The test strip application was carried out on fish from the Tanjung market, Jember district. Positive results from the test strip can be seen from the color change in the detection area.
A change in color to red can indicate that the food contains formaldehyde. The red color comes from the nature of the product resulting from the reaction, namely formic acid. The validation test stage of the test strip with the test kit aims to ensure that the test strip is appropriate and capable of detecting the presence of formaldehyde in the sample accurately and reliably. This test is carried out by reacting formalin with formalin reagent one and formalin reagent two, then shaking until homogeneous and leaving for 5–15 minutes. A positive test is indicated by a purple color change in the solution. The life-time test is carried out to determine how long the test strip can be used. Test strips will be tested for 1 minute to 30 days and stored in an airtight container at room temperature and cold temperatures.
The test strip that we developed can be used without using special methods by simply dipping the strip in the sample and reagent. This certainly makes it easier for people to identify formalin. Test strips, in general, can be used as a first step to sort out the food that enters the body.