Citation :

Nazirov Sh.S, Turaev Kh.Kh, Kasimov Sh A, Normurodov B.A, Alimnazarov B. Kh, "Spectrophotometric Methods for Determination of Cu(II), Zn(II) and Ni(II) ions," International Journal of Engineering Trends and Technology (IJETT), vol. 74, no. 2, pp. 54-74, 2026. Crossref, https://doi.org/10.14445/22315381/IJETT-V74I2P104

Abstract

In this study, the practical aspects of determining Cu(II), Zn(II), and Ni(II) ions using various analytical techniques are investigated. The quantification of these metal ions is crucial for scientific and medical research, as well as for environmental monitoring. In recent years, numerous methods have been developed that ensure high accuracy, speed, and sensitivity in their determination. The paper reviews different analytical methods for determining Cu(II), Zn(II), and Ni(II) ions, emphasizing spectrophotometric and associated physicochemical techniques. The spectrophotometric technique stands out among other analytical methods due to its high precision, rapid operation, and low reagent consumption, making it an effective tool in environmental and biomedical research. Special spectrophotometric reagents, their application conditions, measurement procedures, and possible sources of error are examined in detail. Apart from spectrophotometric analysis, other instrumental techniques like atomic absorption spectroscopy, potentiometric titration, ion-selective electrode measurements, and X-ray fluorescence spectroscopy are systematically reviewed regarding their advantages and drawbacks. These methods enable the detection of trace concentrations of Cu(II), Zn(II), and Ni(II) ions, allowing for a deeper understanding of their biological activity and physiological effects. Overall, the study focuses on the practical applications of analytical chemistry and highlights its significance in medicine, environmental science, and biological research.

Keywords

Determination of Cu(II), Zn(II), and Ni(II) ions, Spectrophotometric Method, Ion-Selective Electrodes, Potentiometric Titration.

References

[1] Stephen E. Bialkowski, Nelson G.C. Astrath, and Mikhail A. Proskurnin, Photothermal Spectroscopy Methods, 2^nd ed., John Wiley and Sons, 2019.
[Google Scholar] [Publisher Link]

[2] Hazrat Ali, and Ezzat Khan, “Environmental Chemistry in the Twenty-First Century,” Environmental Chemistry Letters, vol. 15, no. 2, pp. 329-346, 2017.
[CrossRef] [Google Scholar] [Publisher Link]

[3] Liliya O. Usoltseva, Mikhail V. Korobov, and Mikhail A. Proskurnin, “Photothermal Spectroscopy,” Journal of Applied Physics, vol. 128, no. 19, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[4] Kopach Alexandra Ye, and Fedoriv Olha Ye, “Effects of the Influence of Copper and Zinc on Living Organisms (Literature Review),” Hygiene and Sanitation, vol. 100, no. 2, pp. 172-177, 2021.
[Google Scholar] [Publisher Link]

[5] Natalie G. Robinett, Ryan L. Peterson, and Valeria C. Culotta, “Eukaryotic Copper-Only Superoxide Dismutases (SODs): A New Class of SOD Enzymes and SOD-Like Protein Domains,” Journal of Biological Chemistry, vol. 293, no. 13, pp. 4636-4643, 2018.
[CrossRef] [Google Scholar] [Publisher Link]

[6] Yukina Nishito, and Taiho Kambe, “Absorption Mechanisms of Iron, Copper, and Zinc: An Overview,” Journal of Nutritional Science and Vitaminology, vol. 64, no. 1, pp. 1-7, 2018.
[CrossRef] [Google Scholar] [Publisher Link]

[7] Liliya Kh. Kotelnikova et al., “Beverages and Desserts with Therapeutic and Prophylactic Properties based on Alginate-Containing Biogel from Laminaria -- Vitalgar Cardio,” KnE Life Sciences, pp. 251-258, 2022.
[CrossRef] [Google Scholar] [Publisher Link]

[8] Klaudia Jomova et al., “The Role of Redox-Active Iron, Copper, Manganese, and Redox-Inactive Zinc in Toxicity, Oxidative Stress, and Human Diseases,” EXCLI Journal, vol. 24, pp. 880-954, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[9] Antonyuk Marina Vladimirovna, and Simonova Irina Nikolaevna, “Treatment of Diabetes Mellitus with Physical Factors,” Health Medical Ecology Science, vol. 4, no. 67, pp. 55-65, 2016.
[Google Scholar]

[10] Ekaterina Anatolyevna Troshina, and Evgenia Semyonovna Senyushkina, “The Role of Zinc in the Processes of Synthesis and Metabolism of Thyroid Hormones,” Clinical and Experimental Thyroidology, vol. 16, no. 3, pp. 25-30, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[11] V.N. Zorina, E.A. Evdokimova, and V.L. Reynyuk, “Study of the Interaction of Various Metals with Alpha-2-Macroglobulin and Other Human Blood Proteins in Vitro,” Emergency Medicine, vol. 25, no. 2, pp. 105-111, 2023.
[CrossRef] [Google Scholar] [Publisher Link]

[12] Abdulkerim Kasim Baltaci, Kemal Yuce, and Rasim Mogulkoc, “Zinc Metabolism and Metallothioneins,” Biological Trace Element Research, vol. 183, no. 1, pp. 22-31, 2018.
[CrossRef] [Google Scholar] [Publisher Link]

[13] Maria Maares, and Hajo Haase, “Zinc and Immunity: An Essential Interrelation,” Archives of Biochemistry and Biophysics, vol. 611, pp. 58-65, 2016.
[CrossRef] [Google Scholar] [Publisher Link]

[14] Youichi Ogawa, Tatsuyoshi Kawamura, and Shinji Shimada, “Zinc and Skin Biology,” Archives of Biochemistry and Biophysics, vol. 611, pp. 113-119, 2016.
[CrossRef] [Google Scholar] [Publisher Link]

[15] Md Saidur Rahman et al., “Role of Insulin in Health and Disease: An Update,” International Journal of Molecular Sciences, vol. 22, no. 12, pp. 1-19, 2021.
[CrossRef] [Google Scholar] [Publisher Link]

[16] V.V. Borisov, “Microelements Selenium and Zinc in the Body of Women and Men: Problems and Solutions,” Consilium Medicum, vol. 20, no. 7, pp. 63-68, 2018.
[CrossRef] [Google Scholar] [Publisher Link]

[17] A.A. Olina, and G.K. Sadykova, “Significance of Zinc Deficit in Occurrence of Reproductive Health Disorders (Review of Literature),” Perm Medical Journal, vol. 32, no. 5, pp. 138-143, 2015.
[Google Scholar] [Publisher Link]

[18] E.V. Salnikova, “Human Need for Zinc and its Sources (Review),” Trace Elements in Medicine, vol. 17, no. 4, pp. 11-15, 2016.
[Google Scholar]

[19] N. Tkacheva, and T. Eliseeva, “Nickel (Ni)-Its Importance for the Body and Health, and Where it is Found,” Journal of Healthy Nutrition and Dietology, vol. 2, no. 20, pp. 62-68, 2022.
[CrossRef] [Google Scholar] [Publisher Link]

[20] Yu. M. Polyak, and V.I. Sukharevich, “Soil Enzymes and Soil Pollution: Biodegradation, Bioremediation, Bioindication,” Experimental Articles Soil Fertility, no. 3, pp. 93-96, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[21] Raghad Khalid AL-Ishaq et al., “Flavonoids and Their Anti-Diabetic Effects: Cellular Mechanisms and Effects to Improve Blood Sugar Levels,” Biomolecules, vol. 9, no. 9, pp. 1-35, 2019.
[CrossRef] [Google Scholar] [Publisher Link]

[22] Rama Shanker Dubey, Rajneesh Kumar Srivastava, and Mohammad Pessarakli, Physiological Mechanisms of Nitrogen Absorption and Assimilation in Plants Under Stressful Conditions, Handbook of Plant and Crop Physiology, CRC Press, pp. 579-616, 2021.
[Google Scholar] [Publisher Link]

[23] I.Z. Kamanina, S.P. Kaplina, and F.S. Salikhova, “Content of Heavy Metals in Medicinal Plants,” Scientific Review. Biological Sciences, vol. 1, pp. 29-34, 2019.
[Google Scholar]

[24] S.V. Lukin, and S.V. Selyukova, “Agroecological Assessment of the Microelement Composition of Soybean Plants,” Achievements of Science and Technology of the Agro-Industrial Complex, no. 6, pp. 34-36, 2017.
[Google Scholar]

[25] Vernigora Alexander Nikolaevich et al., “Joint Spectrophotometric Determination of Copper (II) and Nickel (II) by Trilon b,” News of Higher Educational Institutions. Volga Region. Natural Sciences, vol. 4, no. 20, pp. 96-104, 2017.
[CrossRef] [Google Scholar] [Publisher Link]

[26] A.N. Vernigora, N.V. Volkova, and E.N. Guskova, “Simultaneous Spectrophotometric Determination of Copper (II) and Iron (III) in Joint Presence as Complexes with Sulfosalicylic Acid,” Bulletin of Penza State University, vol. 2, no. 17, pp. 85-91, 2017.
[Google Scholar]

[27] Esraa Raafid, Muneer A. Al-Da’amy, and Salih Hadi Kadhim, “Spectrophotometric Determination of Cu(II) in Analytical Sample using a New Chromogenic Reagent (HPEDN),” Indonesian Journal of Chemistry, vol. 20, no. 5, pp. 1080-1091, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[28] Yakubov Erkin Shomuratovich, and Makhmarasulov Mansur Bakhodirovich, “Spectrophotometric Study of Complex Formation of Copper (II) Nitrate and Acetate with Quinazolone-4,” Universum: Technical Sciences, vol. 5, no. 7(124), pp. 17-22, 2024.
[Google Scholar] [Publisher Link]

[29] Yulia Borisovna Elchishcheva, Maria Alekseevna Sitnikova, and Petr Timofeevich Pavlov, “Development of a Spectrophotometric Method for the Determination of Copper (II) Ions with N-Benzyloyl-N'-(Phenylsulfonyl) Hydrazine,” Perm University Bulletin. Chemistry Series, vol. 13, no. 2, pp. 83-91, 2023.
[CrossRef] [Google Scholar] [Publisher Link]

[30] Ch. A. Mamedova et al., “Spectrophotometric Study of Complexation of Copper (II) with 3-((E)-2-Hydroxybenzylidene) Hydrazono) Indolin-2-One,” XXVII Russian Youth Scientific Conference Problems of Theoretical and Experimental Chemistry, Ekaterinburg, no. 27, pp. 460-461, 2017.
[Google Scholar]

[31] Eshchanova Aziza Karrievna et al., “Colorimetric Determination of Copper Ions using Natural Indigo Dye,” Universum: Chemistry and Biology, vol. 7, no. 73, pp. 23-29, 2020.
[Google Scholar] [Publisher Link]

[32] Aivazova Arzu Vagif, Aliyeva Rafiga Alirza, and Chiragov Family Musa, “Complexation of Copper (II) with an Azo Derivative of Benzoylacetone in the Presence of a Third Component,”East European Scientific Journal, vol. 10, no. 1, pp. 147-151, 2016.
[Google Scholar] [Publisher Link]

[33] N. Abo El-Maali et al., “Voltammetric Analysis of Cu (II), Cd (II) and Zn (II) Complexes and their Cyclic Voltammetry with Several Cephalosporin Antibiotics,” Bioelectrochemistry, vol. 65, no. 2, pp. 95-104, 2005.
[CrossRef] [Google Scholar] [Publisher Link]

[34] A.Z. Zalov, “Different Ligand Complexes of Copper (II) with Organic Reagents and their Application to the Photometric Analysis,” Azerbaijan Chemical Journal, 2015.
[Publisher Link]

[35] K.A. Kuliev et al., “Mixed-Ligand Complexes of Copper (II) with Dithiolphenols and Heterocyclic Diamines,” Bulletin of the Voronezh State University of Engineering Technologies, vol. 79, no. 1, pp. 248-256, 2017.
[CrossRef] [Google Scholar] [Publisher Link]

[36] V.I. Mardanova, S.R. Gadzhieva, and F.M. Chyragov, “Study of Copper (II) Complexation with 2,7-Bis (Azo-2-Hydroxy-3-Sulfo-5-Nitrobenzene)-1,8-Dihydroxy-Naphthalene-3,6-Disulfonasodium Salt in the Presence of Third Components,” Applied Chemistry and Biotechnology, vol. 9, no. 3(30), pp. 385-393, 2019.
[CrossRef] [Google Scholar] [Publisher Link]

[37] A.M.O. Mageramov, N.A. Verdizade, and K.A. Kuliev, “Study of the Complexation Reaction of Copper (II) with 2,6-Dimercaptophenol and its Derivatives in the Presence of Aminophenols,” SPbSU Bulletin Series, pp. 211-223, 2016.
[Google Scholar]

[38] K. Stancheva, C. Pasha, and V. Trifonova, “Spectrophotometric Determination of Copper (II) in Waters and Soils using Fuchsine as Reagent,” Oxidation Communications, vol. 46, no. 4, 2023.
[Google Scholar] [Publisher Link]

[39] Turabov Nurmukhammat Turabovich et al., “A New Method for Spectrophotometric Determination of Copper (II) Ions,” Universum: Chemistry and Biology, no. 6-1(108), pp. 46-52, 2023.
[Google Scholar] [Publisher Link]

[40] Yulia Borisovna Elchishcheva, Ksenia S. Gorbunova, and Petr Timofeevich Pavlov, “Development of a Spectrophotometric Method for Determining Cu (II) Ions with N-(2-Hydroxybenzoyl)-N′-(P-Tosyl) Hydrazine in Ammonia Media,” Perm University Bulletin. Chemistry Series, vol. 11, no. 2, pp. 103-113, 2021.
[CrossRef] [Google Scholar] [Publisher Link]

[41] Qudrat Boqiyev et al., “Stripping Voltammetric Determination of Copper Ions using a Graphite-Based Electrochemical Sensor Modified with Pyrocatechol Violet,” Chemical Review and Letters, vol. 8, no. 3, pp. 517-526, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[42] A. Bagheri, and M. Hassani Marand, “Voltammetric and Potentiometric Determination of Cu²⁺ using an Overoxidized Polypyrrole based Electrochemical Sensor,” Russian Journal of Electrochemistry, vol. 56, no. 6, pp. 453-461, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[43] S.M. Turabdzhanov et al., “Modern Eco-Analytical Extraction-Spectrophotometric Method for Copper Determination with 1-(2-Pyridylazo)-2-Naphthol (PAN),” Theoretical Foundations of Chemical Engineering, vol. 54, no. 4, pp. 798-803, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[44] Mahmood Payehghadr, and Farzaneh Nourifard, “Determination of Ultratrace Copper in Water Samples by Differential Pulse Polarography After Solid Phase Extraction,” Orbital: The Electronic Journal of Chemistry, vol. 9, no. 5, pp. 354-359, 2017.
[CrossRef] [Google Scholar] [Publisher Link]

[45] Güler Somer, and Şükrü Kalaycı, “A New and Simple Method for the Simultaneous Determination of Fe, Cu, Pb, Zn, Bi, Cr, Mo, Se, and Ni in Dried Red Grapes using Differential Pulse Polarography,” Food Analytical Methods, vol. 8, no. 3, pp. 604-611, 2015.
[CrossRef] [Google Scholar] [Publisher Link]

[46] Yeliz Karaman, and Necati Menek, “Investigation of Electrochemical Behavior of 4-(2-Pyridylazo) Resorcinol and its Cu²⁺ Complex using Polarographic and Voltammetric Techniques,” International Journal of Electrochemical Science, vol. 16, no. 8, pp. 1-17, 2021.
[CrossRef] [Google Scholar] [Publisher Link]

[47] Tamer Awad Ali, Gehad G. Mohamed, and Ahmed R. Othman, “Design and Construction of New Potentiometric Sensors for Determination of Copper (II) Ion based on Copper Oxide Nanoparticles,” International Journal of Electrochemical Science, vol. 10, no. 10, pp. 8041-8057, 2015.
[CrossRef] [Google Scholar] [Publisher Link]

[48] Wafaa M. Yousef et al., “Potentiometric and Conductometric Studies on Complexes of Folic Acid with Some Metal Ions,” International Journal of Electrochemical Science, vol. 12, no. 2, pp. 1146-1156, 2017.
[CrossRef] [Google Scholar] [Publisher Link]

[49] S.S. Sataeva, “Application of a Titanium Electrode for Potentiometric Determination of Copper, Zinc and Cadmium Ions in Formation Waters,” Non-Ferrous Metals, no. 3, pp. 74-76, 2011.
[Google Scholar] [Publisher Link]

[50] N.P. Matveyko, and S.K. Protasov, “Potentiometric Determination of Copper in Food Products,” Bulletin of the Vitebsk State Technological University, no. 1(20), pp. 155-160, 2011.
[Google Scholar] [Publisher Link]

[51] S.A. Sivkova, E.I. Lyalina, and A.I. Fokina, “Features of the Use of Conductometric Titration in the Analysis of Copper-Containing Compounds of Glutathione,” Young Scientists in Solving Topical Problems of Science, pp. 383-384, 2014.
[Google Scholar] [Publisher Link]

[52] V.N. Losev et al., “Luminescence Determination of Copper (I), Silver (I), Gold (I), and Platinum (II) using 2-Mercapto-5-Benzimidazolesulfonic Acid, also Immobilized on a Silica Surface,” Journal of Analytical Chemistry, vol. 73, no. 1, pp. 50-57, 2018.
[CrossRef] [Google Scholar] [Publisher Link]

[53] A.K. Nomozov et al., “Synthesis of PFG Brand Corrosion Inhibitor and its Quantum Chemical Calculation Results,” Chemical Problems, vol. 23, no. 3, pp. 297-309, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[54] A.M. Pashadzhanov, “Study of the Possibility of using AZO Derivatives of Para-Tert-Butylphenol for Preconcentration and Determination of Copper by Atomic Absorption Method,” Azerbaijan Chemical Journal, no. 2, pp. 109-114, 2014.
[Google Scholar] [Publisher Link]

[55] E. Kh. Atoev, “Study of the Interaction of Chromium and Zinc Salts with Various Organic Reagents,” Consolidation of Intellectual Resources as the Foundation for the Development of Modern Science, pp. 324-330, 2021.
[Google Scholar] [Publisher Link]

[56] Nurmuhammat Turabovich Turabov, Akobir Askarovich Toshov, and Jamoliddin Nasiriddinovich Todzhiev, “Study of the Complexation Reaction of Zinc with 2,7-Dinitroso-1,8-Dioxinaphthalene-3,6-Disulfonic Acid for Analytical Application,” Universum: Chemistry and Biology, no. 12-1(90), pp. 53-57, 2021.
[Google Scholar] [Publisher Link]

[57] Khikmat Bobojonov et al., “Analytical Application of Sorption-Fluorescence Methods for the Determination of Aluminium, Beryllium, and Lead in Environmental Samples,” International Journal of Environmental Analytical Chemistry, vol. 106, no. 1, pp. 142-162, 2026.
[CrossRef] [Google Scholar] [Publisher Link]

[58] Surayyo Razzoqova et al., “Synthesis, Characterization, and Biological Activity of Cu (II) Coordination Complex with 2-Aminoxazole: Experimental and Computational Insights,” Chemical Papers, vol. 79, no. 9, pp. 1-24, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[59] ALI. F. Mohammed, and Sadiq J. Baqir, “Spectrophotometric Determination of Zinc in Pharmaceutical Preparations using a new Synthesized Reagent [4,5-Diphenyl-2-((1E)-(4-(1-(2-Phenylhydrazono) Ethyl) Phenyl) Diazenyl)-4H-Imidazole],” Iraqi National Journal of Chemistry, vol. 15, no. 3, pp. 271-283, 2015.
[Google Scholar] [Publisher Link]

[60] Leposava Pavun, and Snežana Uskoković-Marković, “Spectrophotometric Determination of Hesperidin in Supplements and Orange Juices,” Food and Nutrition, vol. 60, no. 1, pp. 18-23, 2019.
[CrossRef] [Google Scholar] [Publisher Link]

[61] Z. Kh. Misirov et al., “Synthesis and Application of Corrosion Inhibitor for Hydrogen Sulfide Corrosion of Steel,” Indian Journal of Chemical Technology (IJCT), vol. 32, no. 3, pp. 407-411, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[62] P.R. Mammadov, “Simple Spectrophotometric Method for the Determination of Zinc (II) using 4, 4'-Bis-(2, 3, 4-Trihidroksifenilazo)-Difenil,” Transactions of Pedagogical University. Natural Sciences, vol. 1, pp. 48-57, 2020.
[Google Scholar]

[63] Todjiyev Nasiriddinovich Jamoliddin et al., “Spectrophotometric Determination of Microconcentrations of Zinc (II) and Copper (II) in Water and Industrial Alloys using a New Chromogenic Reagent [4-Amino-5-Hydroxy-6-[(5-Methyl-2-Pyridyl) Azo]-3-Sulfo-1-Naphthyl] Sulfonyloxysodium,” Chemical Review and Letters, vol. 7, no. 3, pp. 388-403, 2024. [CrossRef] [Google Scholar] [Publisher Link]

[64] Tatyana Vladimirovna ANTONOVA, Vyacheslav Isaakovich VERSHININ, and Anna Viktorovna POMAZOVA, “New Oxyquinoline Derivatives as Reagents for Spectrophotometric Determination of Transition Metals,” Bulletin of Tyumen State University: Ecology and Nature Management, no. 5, pp. 90-95, 2011.
[Google Scholar] [Publisher Link]

[65] A. Tupis et al., “Extraction-Photometric Study of the Interaction of Zn (II) with 1-(5-Benzyl-2-Thiazolyl)-Azo-2-Naphthol,” Visnyk of Lviv University, vol. 52, pp. 197-202, 2011.
[Google Scholar]

[66] Valery Alekseevich Funtikov, and Anna Aleksandrovna Maruga, “Inversion Voltammetric Methods for Simultaneous Determination of Group IIB Elements (Zn, Hg, Cd) in Water Bodies,” Baltic Maritime Forum, pp. 102-109, 2019.
[Google Scholar] [Publisher Link]

[67] Valery Alekseevich Funtikov et al., “A New Type of Indicator Electrodes for Inversion Voltammetry based on IVA Subgroup Elements,” IV International Baltic Sea Forum, pp. 496-502, 2016.
[Google Scholar] [Publisher Link]

[68] Uchkun Ruzmetov et al., “Determination of Zinc Complexation with an Immobilized Reagent for the Analysis of Environmental Objects,” Talanta, vol. 287, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[69] L.G. Chekanova et al., “Physicochemical Properties and Complex Formation of Ethyl 2-Aryl (Methyl) Sulfonylamino-4,5,6,7-Tetrahydrobenzothiophene-3-Carboxylates,” Russian Journal of General Chemistry, vol. 84, no. 6, pp. 1202-1206, 2014.
[CrossRef] [Google Scholar] [Publisher Link]

[70] S.D. Tataeva, R.Z. Zeynalov, and K.E. Magomedov, “Potentiometric Sensor for the Determination of Zinc Ions,” Analytics and Control, vol. 25, no. 3, pp. 205-211, 2021.
[CrossRef] [Google Scholar] [Publisher Link]

[71] Eleonora Zhumaeva, Uchkun Ruzmetov, and Zulaykho Smanova, “Methods of the Determination of Heavy Metals in Water and the Toxic Effect of Heavy Metals on the Life,” Fergana State University, no. 3, pp. 340-348, 2023.
[Google Scholar] [Publisher Link]

[72] A.A. Erina et al., “Modification of the Method for Determining Zinc in Insulin by Atomic Absorption Spectrometry,” Bulletin of the Scientific Center for Expertise of Medical Products, vol. 13, no. 3, pp. 403-410, 2023.
[CrossRef] [Google Scholar] [Publisher Link]

[73] Todjiyev Jamoliddin Nasiriddinovich et al., “Determination of Ni (II) Ions in Natural Objects and Industrial Alloys via a Spectrophotometric Method with 4,5-Dihydroxy-3,6-Dinitrosonaphthalene-2,7-Disulfoxic Acid,” Chemical Review and Letters, vol. 7, no. 5, pp. 895-911, 2024.
[CrossRef] [Google Scholar] [Publisher Link]

[74] Lingling Zhao et al., “Determination of Cadmium (II), Cobalt (II), Nickel (II), Lead (II), Zinc (II), and Copper (II) in Water Samples using Dual-Cloud Point Extraction and Inductively Coupled Plasma Emission Spectrometry,” Journal of Hazardous Materials, vol. 239-240, pp. 206-212, 2012.
[CrossRef] [Google Scholar] [Publisher Link]

[75] Endale Tesfaye et al., “Electrochemical Determination of Zinc (II) using N¹-hydroxy-N¹, N²-Diphenylbenzamidine and Multi-Walled Carbon Nanotubes Modified Carbon Paste Electrode,” Heliyon, vol. 9, no. 6, pp. 1-16, 2023.
[Google Scholar] [Publisher Link]

[76] Merlin Mary Mathew, and Anandaram Sreekanth, “Zn²⁺Ion Responsive Fluorescent Chemosensor Probe of Thiophene-Diocarbohydrazide Derivatives,” Inorganica Chimica Acta, vol. 516, pp. 1-7, 2021.
[CrossRef] [Google Scholar] [Publisher Link]

[77] Nigora Qutlimurotova et al., “Amperometric Determination of Cerium (III) using 2,7-Dinitrozo-1,8-Dihydroxynaphthalene-3,6-Disulfonic Acid Solution,” Czech Journal, vol. 17, no. 36, pp. 735-749, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[78] Z.N. Todzhiev, Sh.N.O.I. Olimzhonova, and N.T. Turabov, “2,7-Dinitroso-1,8-Dioxynaphthalene-3,6-Disulfonic Acid as an Analytical Reagent for Spectrophotometric Determination of Nickel (II),” Universum: Chemistry and Biology, no. 12-1(90), pp. 48-52, 2021.
[Google Scholar] [Publisher Link]

[79] R.A. Aliyeva et al., “Spectrophotometric Study of Complexformation of Nickel (Ii) with 3-(1-Phenyl-2,3-Dimethiyl-Pirozolon-5) Azopentadion-2,4 in the Presence of Third Components,” Azerbaijan Chemical Journal, no. 4, pp. 12-16, 2017.
[Google Scholar] [Publisher Link]

[80] Kerim Kuliev et al., “Spectrophotometric Determination of Nickel (II) using 5-(2-Bromo-5-Methoxybenzylidene)-Thiazolidine-2,4-Dione,” Perm University Bulletin. Chemistry Series, vol. 14, no. 1, pp. 5-14, 2024.
[CrossRef] [Google Scholar] [Publisher Link]

[81] Sagdullaeva Laylo et al., “New and Effective Analytical Reagent of 5-(4-Aminophenyl)-1,3,4-Oxadiazole-2-Thiol in the Determination of Copper and Lead,” Analytical & Bioanalytical Electrochemistry, vol. 14, no. 12, 2022.
[Google Scholar] [Publisher Link]

[82] Abror Nomozov et al., “Antibacterial Evaluation and Prediction of the Ability of Salsola Oppositifolia Extract,” Journal of Chemical Letters, vol. 6, no. 3, pp. 203-211, 2025.
[Google Scholar] [Publisher Link]

[83] Nataliia A. Leonova, Oleg I. Yurchenko, and Anastasiia S. Batrak, “Spectrophotometric Determination of Concentrations of Co (II) and Ni (II) in Complex with 1- (2-Pirydylazo) -2-Naphthol in Aqueous Micellar Medium,” Kharkiv University Bulletin. Chemical Series, no. 24, pp. 153-160, 2014.
[CrossRef] [Google Scholar] [Publisher Link]

[84] Davron Polvon o‘g‘li Kuronboyev et al., “Development of a Method for Cyclic Voltametric Determination of Copper (II) Ions in the Composition of Technological Objects,” Chemical Review and Letters, vol. 8, no. 3, pp. 469-481, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[85] Ali Z. Zalov, and Kiril B. Gavazov, “Extractive Spectrophotometric Determination of Nickel with 2-Hydroxy-5-Iodothiophenol and Diphenylguanidine,” Chemical Journal, vol. 4, no. 5, pp. 20-25, 2014.
[Google Scholar]

[86] Xiao-Dong Li, and Qing-Zhou Zhai, “Spectrophotometric Determination of Nickel using Chlorophosphonazo-III,” Chemical Science Transactions, vol. 3, no. 3, pp. 1023-1026, 2014.
[Google Scholar]

[87] Raghunathan Muthuselvi, “Selective Determination of Nickel (II) in Water, Effluent and Alloy Samples using Isonicotinohydroxamic Acid as Analytical Reagent,” Chemical Science Transactions, vol. 3, no. 1, pp. 403-409, 2014.
[Google Scholar]

[88] Masar A. Awad, and Hussain J. Mohammed, “Spectrophotometric Determination of Trace Nickel (II) in Tea Leaves using Antipyrylyl Azo-2,7-Naphthalendiol as a New Reagent,” Chemical Science Transactions, vol. 3, no. 3, pp. 1115-1123, 2014.
[Google Scholar]

[89] Rehana Khanam, Saba Khan, and Rekha Dashora, “3-Hydroxy-3-n-Propyl-1-(4-Sulphonamidophenyl) Triazene: A New Reagent for Spectrophotometric Determination of Nickel (II),” Oriental Journal of Chemistry, vol. 30, no. 2, pp. 837-841, 2014.
[CrossRef] [Google Scholar] [Publisher Link]

[90] A.K. Nomozov et al., “Recent Developments in Polymer-Based Composite Anticorrosion Coatings: Materials, Mechanisms and Applications,” International Journal of Corrosion and Scale Inhibition, vol. 14, no. 3, pp. 1018-1684, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[91] Sana Rhajab Bakir, and Saadiyah Ahmed Dhahir, “Cloud Point Extraction Spectrophotometric Determination of Trace Amount of Nickel using SALEN as Reagent in Waste Water of Iraq,” Online International Interdisciplinary Research Journal, vol. 3, pp. 9-21, 2013.
[Google Scholar] [Publisher Link]

[92] XIONG Dao-ling et al., “Simultaneous Determination of Iron, Copper, Chromium and Nickel by Multi-Wavelength Spectrophotometry,” Nonferrous Metals Science and Engineering, vol. 4, no. 6, pp. 13-18, 2013.
[CrossRef] [Google Scholar] [Publisher Link]

[93] Rehana Khanam, Saba Khan, and Rekha Dashora, “Direct Spectrophotometric Determination of Nickel (II) with O-Chlorophenylazo-Bis-Acetoxime,” Oriental Journal of Chemistry, vol. 29, no. 2, pp. 603-608, 2013.
[CrossRef] [Google Scholar] [Publisher Link]

[94] N.M. Modawe, and M.A.Z. Eltayeb, “H-Point Standard Addition Method for Simultaneous Spectrophotometric Determination of Cobalt (II) and Nickel (II),” Advances in Analytical Chemistry, vol. 3, no. 1, pp. 1-7, 2013.
[CrossRef] [Google Scholar] [Publisher Link]

[95] C. Viswanatha, N. Devanna, and K.B. Chandrasekhar, “Direct and Derivative Spectrophotometric Determination of Nickel (II) using 2,4-Dimethoxybenzaldehyde Isonicotinoyl Hydrazone (DMBIH),” International Journal of Advances in Pharmacy, Biology and Chemistry, vol. 2, pp. 380-384, 2013.
[Google Scholar]

[96] Jibran Iqbal et al., “Ultra-Sensitive Spectrophotometric Determination of Nickel After Complexation and Membrane Filtration,” Microchimica Acta, vol. 177, no. 1-2, pp. 195-200, 2012.
[CrossRef] [Google Scholar] [Publisher Link]

[97] Morteza Bahram, and Somayeh Khezri, “Multivariate Optimization of Cloud Point Extraction for Simultaneous Spectrophotometric Determination of Cobalt and Nickel in Water Samples,” Analytical Methods, vol. 4, no. 2, pp. 384-393, 2012.
[CrossRef] [Google Scholar] [Publisher Link]

[98] Rajni Rohilla, and Usha Gupta, “Simultaneous Determination of Cobalt (II) and Nickel (II) by First-Order Derivative Spectrophotometry in Micellar Media,” Journal of Chemistry, vol. 9, no. 3, pp. 1357-1363, 2012.
[CrossRef] [Google Scholar] [Publisher Link]

[99] Prashant A. Borade, Anandkumar S. Gupta, and V.D. Barhate, “Development of Extractive Spectrophotometric Determination of Nickel (II) with Isatin-3-Semicarbazone (HISC) as Analytical Reagent,” Asian Journal of Research in Chemistry, vol. 4, no. 12, pp. 1905-1907, 2011.
[CrossRef] [Google Scholar] [Publisher Link]

[100] V.A. Kopilevich et al., “Inversion-Chronopotentiometric Determination of Microquantities of Nickel and Cobalt in Waters,” Journal of Water Chemistry and Technology, vol. 37, no. 5, pp. 248-252, 2015.
[CrossRef] [Google Scholar] [Publisher Link]

[101] A.M. Zakharkiva, and S.V. Shumar, “Potentiometric Determination of Nickel (II) with Sodium Diethyldithiocarbamate (NaDEDC),” Journal of Physics: Conference Series, vol. 1611, no. 1, pp. 1-6, 2020.
[CrossRef] [Google Scholar] [Publisher Link]

[102] Nazira Madusmanova et al., “Determination of Mn (II) Ions in Soil Samples by Means of a Sensitive Sorption-Spectroscopic Method,” Talanta, vol. 297, 2025.
[CrossRef] [Google Scholar] [Publisher Link]

[103] Pochitskaya, Irina Mikhailovna, Elena Sergeevna Aleksandrovskaya, and Olga Vladimirovna Chekun, “Features of Nickel Determination by Electrothermal Atomic Absorption Spectrometry,” Food Industry: Science and Technology, vol. 11, no. 2, pp. 64-70, 2018.
[Google Scholar] [Publisher Link]

[104] Sergeev Gennady Mikhailovich et al., “Flow-Injection Conductometry. Chelatometric Titration of Cu (II), Ni (II) and Pb (II) Ions,” Bulletin of the Lobachevsky University of Nizhny Novgorod, no. 4-1, pp. 98-102, 2011.
[Google Scholar] [Publisher Link]

[105] Hu Shun-feng et al., “Determination of Ni, Cr, Mg, Al and Co in Nickel-Bearing Laterite by Inductively Coupled Plasma-Atomic Emission Spectrometry,” Rock and Mineral Analysis, vol. 30, no. 4, pp. 465-468, 2011.
[Google Scholar] [Publisher Link]

[106] S.Z. Mohammadi, D. Afzali, and D. Pourtalebi, “Flame Atomic Absorption Spectrometric Determination of Trace Amounts of Lead, Cadmium and Nickel in Different Matrixes After Solid Phase Extraction on Modified Multiwalled Carbon Nanotubes,” Central European Journal of Chemistry, vol. 8, no. 3, pp. 662-668, 2010.
[CrossRef] [Google Scholar] [Publisher Link]

[107] S. Vellaichamy, and K. Palanivelu, “Preconcentration and Separation of Copper, Nickel and Zinc in Aqueous Samples by Flame Atomic Absorption Spectrometry After Column Solid-Phase Extraction onto MWCNTs Impregnated with D2EHPA-TOPO Mixture,” Journal of Hazardous Materials, vol. 185, no. 2-3, pp. 1131-1139, 2011.
[CrossRef] [Google Scholar] [Publisher Link]

[108] Luana S. Nunes et al., “Multi-Element Determination of Cu, Fe, Ni and Zn Content in Vegetable Oils Samples by High-Resolution Continuum Source Atomic Absorption Spectrometry and Microemulsion Sample Preparation,” Food Chemistry, vol. 127, no. 2, pp. 780-783, 2011.
[CrossRef] [Google Scholar] [Publisher Link]

[109] S.T. Trivedi, and P.A. Sathe, “Simultaneous Quantitation of Nickel and Zinc in Industrial Effluent using Sampled DC Polarography,” Asian Journal of Research in Chemistry, vol. 5, no. 5, pp. 582-585, 2012.
          [CrossRef] [Google Scholar] [Publisher Link]