Continuous Flow injection analysis-turbidimetric determination of Cobalt (II) ion in different alloy samples using linear array of six snow-white LEDs as a source and one solar cell as an energy transducer

<ns3:p> Background Accurate determination of cobalt (Co <ns3:sup>2+</ns3:sup> ) in industrial samples is essential due to its environmental and industrial significance. This work presents a fast, sensitive, and cost effective analytical method based on precipitation reaction and flow injection analysis (FIA). Methods Cobalt ions were estimated through the formation of a pale orange precipitate via reaction of sodium nitroprusside in acidic medium. The reaction mechanism was investigated using Fourier-transform infrared (FTIR) and UV-Vis spectroscopy. A homemade NAG-6SX1-1D analyzer, equipped with six white LEDs and a solar-cell photodetector, was utilized to measure the analytical signal. Experimental factors affecting sensitivity were systematically optimized. the method performance was evaluated in terms of linearity, accuracy, precision, and LOD, and compare with a reference UV-Vis spectrophotometric method at at λ <ns3:sub>max</ns3:sub> = 512 nm. Results the method exhibited a good linear range of 0.005–8 mmol. L <ns3:sup>−1</ns3:sup> with correlation coefficient (r) of 0.9959 and linearity (R <ns3:sup>2</ns3:sup> ) of 99.20%. high precision was achieved with relative standard deviation (RSD%) lower than 0.2% for the repetitions (n = 6) were significantly at 5 and 7 mmol. L <ns3:sup>−1</ns3:sup> . The limit of detection (LOD) was 0.413 ng/sample. The use of continuous dilution in FIA enables effective handling of both diluted or concentrated samples. The proposed method showed improve performance relative to the reference method. Conclusion The developed method is straightforward, sensitive, and reliable for determining Co <ns3:sup>2+</ns3:sup> ions in industrial samples. Its wide linear range, low detection limit, and high precision make it a practical alternative to conventional spectrophotometric methods, especially for routine and rapid analysis. </ns3:p>