Solid-phase extraction of some food dyes on sea sponge column and determination by UV–vis spectrophotometer

Preconcentration methods are widely used before the determination of analytes, which have low concentration values in the samples. One group of these analytes which need to be preconcentrated before determination is food dyes. This work was aimed to develop a new method to determine Ponceau 4R and Sudan Orange G dyes by using a column filled with sea sponge, as solid-phase. Sea sponge is firstly used in this work for the preconcentration of the food dyes. The method is applied to various food samples after optimizing analytical parameters such as HCl concentration, eluent type, sample volume, flow rates of solutions, and matrix effects. The detection limits based on three times the standard deviations for the blanks were found in the range of 0.002 μg/L and 1.9 × 10−4 μg/L for Ponceau 4R and Sudan Orange G dyes, respectively. Calibration standards were prepared in the ranges of 8.5 × 10−7–8.5 × 10−5 mol/L and 2.34 × 10−5–2.34 × 10−3 mol/L for Ponceau 4R and Sudan Orange G dyes, respectively, and the correlation coefficient was 0.999.