Poly(N-isopropylacrylamide-co-N,N′-methylene bisacrylamide) monolithic column embedded with γ-alumina nanoparticles microextraction coupled with high-performance liquid chromatography for the determination of synthetic food dyes in soft drink samples

The present work proposes a study of the synthesis of poly(N-isopropylacrylamide-co-N,N′-methylene bisacrylamide) monolithic column embedded with γ-alumina nanoparticles and its applications to the extraction of synthetic food dyes in soft drink samples. The monolithic column was synthesized inside fused silica capillaries using thermally initiated free-radical polymerization with N-isopropylacrylamide (NIPAAm) as the monomer, N,N′-methylene bisacrylamide (MBAAm) as the cross-linker, dimethylsulfoxide (DMSO) and dodecanol as the porogen. γ-Alumina nanoparticles were introduced to prevent the swelling of the organic polymer and enhance the loading capacity. In order to obtain optimum experimental conditions, sample pH, sample flow rate, sample volume, eluent flow rate were investigated. Under the optimum conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. When applied to the determination of four synthetic food dyes (Tartrazine, Sunset Yellow, Allura Red, and Azorubine) in soft drink samples, satisfactory recoveries were obtained in the range of 90.4–109.2%.