DETERMINATION OF SELECTED HEAVY METAL IONS IN FOOD PRODUCTS USING ADVANCED VOLTAMMETRIC ANALYSIS

ISSN: 2582-4686 SJIF 2021-3.261,SJIF 20222.889, 2024-6.875 ResearchBib IF: 9.948 / 2024 VOLUME-5, ISSUE-12 434 DETERMINATION OF SELECTED HEAVY METAL IONS IN FOOD PRODUCTS USING ADVANCED VOLTAMMETRIC ANALYSIS Authors: Muhammad Rajabov¹, Sergey Aronbayev¹, Hasan Nasimov¹ ¹ Institute of Biochemistry, Samarkand State University, Samarkand, Uzbekistan Abstract Heavy metal contamination in food products poses a significant threat to public health due to their persistence, bioaccumulation, and toxicity. Industrial emissions, pesticide residues, and inadequate agricultural practices contribute to the presence of metals such as Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ in commonly consumed foods. This study investigates the quantitative determination of heavy metal ions in wheat flour, rice flour, dried potatoes, and dried carrots using voltammetric analytical methods. Samples were digested using nitric acid and hydrogen peroxide, followed by precise electrochemical measurement. Analytical calibration, interference studies, and reproducibility assessments were conducted for method validation. Results demonstrated slightly elevated concentrations of Pb²⁺ and Cd²⁺ in selected samples, while Cu²⁺ and Zn²⁺ remained within acceptable regulatory limits. The findings highlight the necessity of routine monitoring and the suitability of voltammetric techniques for rapid, sensitive, and cost-effective heavy metal determination in food matrices. Keywords: heavy metals, food safety, voltammetric analysis, Pb²⁺, Cd²⁺, Cu²⁺, Zn²⁺, contamination monitoring 1. Introduction Food safety remains one of the most critical global challenges, especially in regions where industrialization and agricultural expansion have intensified environmental contamination. Heavy metals—particularly lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn)—are frequently detected in soil, water, and food products. These metals exhibit non-biodegradable behavior and accumulate in living organisms, resulting in severe health implications including neurotoxicity, kidney damage, metabolic disorders, carcinogenic effects, and impaired growth. Lead exposure, even at trace levels, affects children’s cognitive development and causes chronic cardiovascular damage, whereas cadmium is associated with renal dysfunction and bone fragility. Copper and zinc, although essential micronutrients, become toxic at elevated concentrations, disrupting enzymatic activity and metabolic pathways. Electrochemical methods, particularly voltammetric techniques, have become dominant analytical tools for heavy metal detection due to their high sensitivity, selectivity, low detection limits, and minimal sample consumption. Compared with spectroscopic techniques (AAS, ICP-OES), voltammetry offers rapid analysis, cost efficiency, and portability, making it suitable for both laboratory and field applications. This study aims to quantify Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ ions in selected food products using advanced voltammetric analysis and evaluate their compliance with international food safety standards. 2. Materials and Methods 2.1 Sample Collection ISSN: 2582-4686 SJIF 2021-3.261,SJIF 20222.889, 2024-6.875 ResearchBib IF: 9.948 / 2024 VOLUME-5, ISSUE-12 435 Food samples were collected from local markets in Samarkand, Uzbekistan. The following materials were analyzed: • Wheat flour • Rice flour • Dried potato samples • Dried carrot samples Each sample was homogenized and stored in airtight containers prior to digestion. 2.2 Wet Digestion Procedure Approximately 1.0 g of each sample was transferred into Teflon digestion vessels. A mixture of: • 8 mL HNO₃ (65%) • 2 mL H₂O₂ (30%) was added to each vessel. Digestion was performed using a controlled temperature program until complete mineralization was achieved. The resulting clear solutions were diluted to 50 mL using deionized water. 2.3 Voltammetric Analysis Electrochemical measurements were performed using a multi-mode voltammetric workstation equipped with: • Working electrode: modified carbon electrode • Reference electrode: Ag/AgCl • Counter electrode: platinum wire Calibration curves were constructed using standard solutions of Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ at known concentrations. Analytical validation included: • Limit of detection (LOD) • Limit of quantification (LOQ) • Linearity (R² > 0.995) • Repeatability (RSD < 5%) • Interference studies via standard addition 2.4 Statistical Analysis All measurements were performed in triplicate. Data were analyzed using OriginPro and GraphPad Prism to generate statistical plots, bar charts, and concentration curves. 3. Results 3.1 Heavy Metal Concentrations The concentrations of Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ in the analyzed samples are shown below. Sample Pb²⁺ (mg/kg) Cd²⁺ (mg/kg) Cu²⁺ (mg/kg) Zn²⁺ (mg/kg) Wheat flour 0.15 0.12 0.05 0.20 Rice flour 0.12 0.09 0.06 0.18 Dried potatoes 0.18 0.14 0.07 0.22 Dried carrots 0.13 0.10 0.05 0.19 3.2 Comparison with Permissible Limits Regulatory limits (WHO/FAO): • Pb²⁺: 0.10 mg/kg ISSN: 2582-4686 SJIF 2021-3.261,SJIF 20222.889, 2024-6.875 ResearchBib IF: 9.948 / 2024 VOLUME-5, ISSUE-12 436 • Cd²⁺: 0.10 mg/kg • Cu²⁺: 0.20 mg/kg • Zn²⁺: 0.50 mg/kg Pb²⁺ and Cd²⁺ slightly exceeded permissible limits in wheat flour and dried potatoes. 3.3 Graphical Analysis Figure 1. Bar chart of Heavy Metal Concentration in Food Samples Concentration levels of Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ in wheat flour, rice flour, dried potatoes, and dried carrots. The bar chart illustrates the measured concentrations of the four heavy metals across all food samples. Pb²⁺ and Cd²⁺ show noticeably higher levels in wheat flour and dried potatoes, while Cu²⁺ and Zn²⁺ remain relatively stable across samples. Figure 2. Metal concentration curves vs. permissible levels This graph presents the measured values plotted against international regulatory thresholds. Pb²⁺ and Cd²⁺ exceed the maximum allowable concentration (0.10 mg/kg) in wheat flour and dried ISSN: 2582-4686 SJIF 2021-3.261,SJIF 20222.889, 2024-6.875 ResearchBib IF: 9.948 / 2024 VOLUME-5, ISSUE-12 437 potatoes, whereas Cu²⁺ and Zn²⁺ remain below their respective limits (0.20 mg/kg and 0.50 mg/kg). The graphical comparison clearly visualizes the margin of exceedance and compliance. Graphical Construction Details: Both figures are constructed using the mean of triplicate measurements, with error bars representing standard deviations. Statistical processing and visualization were performed using OriginPro and GraphPad Prism, ensuring high-accuracy numerical rendering. All axes were calibrated with uniform scaling for comparison clarity. 4. Discussion The presence of heavy metals, especially Pb²⁺ and Cd²⁺, beyond regulatory limits raises substantial concerns regarding food safety. Wheat flour and dried potatoes showed the highest contamination, possibly due to soil composition, irrigation water, or environmental exposure during cultivation and storage. Electrochemical analysis proved highly effective due to: • Rapid detection • Low sample volume • High precision • Minimal chemical consumption Comparative analysis with international studies confirms similar contamination patterns in regions with agricultural-industrial overlap. The technique's reproducibility and sensitivity highlight its suitability for routine monitoring in developing countries where advanced spectrometric equipment may not be readily available. 5. Conclusion 1. Heavy metals were successfully quantified using voltammetric analysis. 2. Pb²⁺ and Cd²⁺ levels exceeded international safety limits in selected food samples. 3. 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