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The method for determination of Fe(III) using complex formation reaction between the extracted purple cabbage and Fe(III) detected by smartphone was developed in this work. Adobe Photoshop CS6 program for photos evaluation from the smartphone was used. The parameters affecting the analytical results were studied for instant optimal conditions for extraction and photo taking. The obtained results showed that distilled water was an optimal condition for purple cabbage powder extraction. In addition, photography taken under the white sample holder with a focusing distance of 10 cm in natural light on the scene was an optimal condition for photo taking. Under the optimum conditions, linearity range was in the range of 100-900 µM with correlation coefficient (r2) of 0.9966 (linearity equation: y = 0.0001x + 0.0190) and limit of detection (3sd) was 73 µM. Moreover, the performance of the proposed method has been compared to that of UV-Vis spectrophotometric method as a standard method. According to the paired t-test, the results of the two methods are not significantly different at 95 % confidence (tstat = 0.09, tcritical = 3.18).
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