Dispersive liquid-liquid microextraction coupled with digital image colorimetric analysis for detection of total iron in water and food samples

•The DLLME was efficiently coupled with digital image colorimetric analysis.•A computer-assisted method was used to quantify the content of colored substance.•The proposed method has enough sensitivity, selectivity and accuracy for analysis.•The proposed method was applied to real sample determination of total iron.•The proposed method is simple, low cost and potentially portable.

A simple and low cost assay for total iron in various samples based on dispersive liquid-liquid microextraction (DLLME) coupled with digital scanning image analysis was proposed. Orthogonal experiment design was utilized to optimize the amount of extraction solvent and disperser solvent, O-phenanthroline concentration and buffer pH. Under the optimum conditions, the calibration curve was linear over the range of 0.047-1.0 μg mL−1 (R2 > 0.99) of iron. The limit of detection (LOD) for iron was 14.1 μg L−1 and limit of quantification (LOQ) was 46.5 μg L−1. The relative standard deviations for seven replicate determinations of 0.5 μg mL−1 of iron was 3.75%. The method was successfully applied for analysis of total iron in water and food samples without using any spectral instrument and it could have a potential industrial impact in developing fast and portable devices to analyze the iron content in water and certain foods.

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