Preconcentration and Measurement of Sudan IV Utilizing the UA-d-μ-SPE Method with a Smartphone as a Simple Measurement Tool in Food and Water Samples

In analytical chemistry, the use of the simplest tool that provides the possibility of on-site measurement, low cost, and simple equipment has always been an area of interest for researchers. In recent years, the use of smartphones as an available tool can have these features. In this study, Bi2O3/ZnO/Pd adsorbent was used for preconcentration and measurement of Sudan IV color as one of the azo family colors in food and water samples, exploiting ultrasonic-assisted dispersive micro solid phase extraction (UA-d-μ-SPE) method along with a smartphone. The structure of this adsorbent was examined by XRD, SEM, and EDS analyses. Factors such as the amount of adsorbent (5.1 mg), sample solution pH (7.1), washing solvent volume (430.0 μL), and adsorption time (65 seconds) were optimized, utilizing central composite design (CCD) method. The type of washing solvent (methanol) and desorption time (45 seconds) were also optimized using the one-parameter-at-a-time method. In the best conditions, the limit of detection (LOD) was 5.58 ng mL-1, and the linear detection range (LDR) for this color was 20-1100 ng mL-1. The enrichment factor (EF) was also computed as 22.87. In addition, the relative standard deviation (RSD%) was acquired as 3.91 with n=5.