ABSTRACT
An efficient colorimetric sensor was developed using a high-density deep eutectic solvent (HD-DES) for the trace detection and speciation of iron in various milk samples. A liquid colorimetric probe was fabricated by dissolving ferrozine (FZ) in HD-DES prepared from TBABr and PBA. The prederivatization of Fe2+ via complexation with FZ on the HD-DES/FZ probe provided the [Fe(FZ)3]4- complex, which led to a color change from pale yellow to purple before it was simultaneously extracted by HD-DES. The Fe3+ content was calculated by subtracting the amount of Fe2+ from the total Fe content following the reduction of Fe3+ to Fe2+ by L-ascorbic acid in an acid buffer. Under the optimized conditions, the proposed colorimetric sensor exhibited appreciable linearity in the concentration range of 0.003-0.04 mg L-1, a low limit of detection (0.95 µg L-1), high enrichment factor (50), and outstanding repeatability. The liquid colorimetric probe was successfully applied for the determination and speciation of iron in milk samples, and the results were compared with those obtained using the standard atomic absorption spectrometry method. Moreover, quantitative analysis was performed on a smartphone using the Image J application to estimate the color intensity change, which eliminated the requirement of sophisticated scientific instruments.
Subject(s)
Liquid Phase Microextraction , Milk , Animals , Colorimetry , Deep Eutectic Solvents , Iron/analysis , Limit of Detection , Liquid Phase Microextraction/methods , Milk/chemistry , Solvents/chemistryABSTRACT
A novel liquid colorimetric sensor based on deep eutectic solvent (DES) was developed for the preconcentration and detection of Pb2+ in fruit juice, milk and cereal samples. The colorimetric probe was simply fabricated by adding dithizone (DZ) into DES, prepared from choline chloride and phenol. Pb2+ was formed complex with DZ in the probe, providing hydrophobic complex of [Pb-DZ] which was simultaneously extracted into DES and the color was changed from light orange to carmine red. The enriched [Pb-DZ] in DES was detected using spectrophotometer at 520 nm and naked-eyes. In addition, a smartphone in combination with an Image J program was used as an alternative detection device. Under optimal conditions, the enrichment factor was 92 with LOD of 2.1 µg L-1 and the linear range was 0.007-0.075 mg L-1. The proposed liquid colorimetric sensor was successfully applied for Pb2+ detection in various food samples and the results were in good agreement with those obtained by FAAS. The advantages of this method are simple, rapid, environmental friendly and low cost.
Subject(s)
Liquid Phase Microextraction , Animals , Colorimetry , Limit of Detection , Milk , SolventsABSTRACT
A simple and highly sensitive method is developed for the simultaneous determination of Ni2+, Cr2O72-, Co2+, and Hg2+ by using in syringe low density solvent-dispersive liquid liquid microextraction (ISLD-DLLME), followed by high performance liquid chromatography with a UV detector. The four metal ions were derivatized with pyrrolidine dithiocarbamate (PDC) based on complexation before their enrichment by ISLD-DLLME in which 1-octanol and methanol were used as the extraction solvent and the dispersive solvent, respectively. The extraction was performed in a commercially available syringe under vortex agitation. Phase separation was achieved without centrifugation, and the extraction phase was easily collected by moving the syringe plunger. Parameters affecting the extraction efficiency were studied and optimized. Under the optimum conditions, the four metal-PDC complexes were detected within 18 min, and ISLD-DLLME could increase the detection sensitivity in the range of 64-230 times compared to the direct HPLC analysis. The obtained limits of detection (LODs) were found to be in the range of 0.011-2.0 µg L-1. The applicability of the method is demonstrated for freshwater fish, shrimp, and shellfish samples. In addition, the results are in good agreement with those obtained by inductively-coupled plasma-optical emission spectrometry (ICP-OES).
