OICC Press International Journal of Industrial Chemistry 2228-5547 16 4 2025 12 30 Evaluation of Enzyme Activity Measurement Methods: Application of a Glucometer as a Rapid and Low-Cost Alternative to HPLC 10.57647/j.ijic.2025.1604.17 EN Saloomeh Shoaei Naeeni Department of Biology, SR.C., Islamic Azad University, Tehran, Iran Bijan Bambai Systems Biotechnology Department, National Institute of Genetic Engineering and Biotechnology (NIGEB), Shahrak-e Pajoohesh, Km 15, Tehran - Karaj Highway, Tehran, Iran Bagher Yakhchali Energy and Environmental Biotechnology Department, National Institute of Genetic Engineering and Biotechnology (NIGEB), Shahrak-e Pajoohesh, Km 15, Tehran - Karaj Highway, Tehran, Iran Parvaneh Saffarian Department of Biology, SR.C., Islamic Azad University, Tehran, Iran Zarrin Minuchehr Systems Biotechnology Department, National Institute of Genetic Engineering and Biotechnology (NIGEB), Shahrak-e Pajoohesh, Km 15, Tehran - Karaj Highway, Tehran, Iran Journal Article 2025 12 30 Glucose isomerase (GI) catalyzes the reversible conversion of glucose to fructose and plays a major role in producing high-fructose corn syrup (HFCS). Accurate and rapid measurement of GI activity is essential for process optimization and quality control. This study compared two analytical methods—high-performance liquid chromatography (HPLC) and a portable glucometer—for determining GI activity in recombinant Escherichia coli BL21 cultures grown under various conditions. Enzyme activity was quantified by monitoring glucose consumption and fructose production. Statistical analysis, including regression and independent t-tests, revealed a strong correlation between glucometer and HPLC results (R² = 0.96, p = 0.0001) with no significant difference in mean activities. The findings demonstrate that the glucometer, despite its simplicity and low cost, provides reliable data comparable to HPLC. This approach provides a rapid and cost-effective alternative for routine glucose isomerase activity screening in laboratory and industrial settings.