RESUMO
A highly selective molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatography (HPLC) ultraviolet-visible detection was developed for the simultaneous isolation and determination of four Sudan dyes (I, II, III and IV) in catsup products. The novel molecularly imprinted microspheres (MIM) were synthesized by aqueous suspension polymerization using phenylamine and naphthol as template, which showed high affinity to Sudan dyes in aqueous solution. In order to develop a selective extraction protocol for simultaneous determination the four Sudan dyes from catsup products, the molecular recognition properties of MIM as a SPE sorbent were evaluated. Under the optimized condition, good linearity was obtained from 0.01 to 2.5 µg g(-1) (r(2)≥ 0.9990) with the relative standard deviations of less than 3.4%. This proposed MISPE-HPLC procedure eliminated the effect of template leakage on quantitative analysis and could be applied to direct determination of four Sudan dyes in complicated food samples.
Assuntos
Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Condimentos/análise , Microesferas , Impressão Molecular/métodos , Extração em Fase Sólida/métodos , Compostos Azo/química , Corantes/química , Análise de Alimentos/métodos , Modelos Lineares , Naftóis/química , Naftóis/isolamento & purificação , Reprodutibilidade dos Testes , Solventes/químicaRESUMO
A new pretreatment method, solid-phase extraction combined with dispersive liquid-liquid microextration (SPE-DLLME), was proposed in first time for the determination of clenbuterol (CLB) in porcine tissue samples. The tissue samples were firstly extracted by SPE, then its eluents were used as dispersant of the followed DLLME for further purification and enrichment of CLB. Various parameters (such as the type of SPE sorbent, the type and volume of elution solvent, the type and volume of extractant and dispersant, etc.) that affected the efficiency of the two steps were optimized. Good linearity of CLB was ranged from 0.19 µg/kg to 192 µg/kg with correlation coefficient (r²) of 0.9995. The limit of detection (LOD) was 0.07 µg/kg (S/N=3) and the recoveries at three spiked levels were ranged from 87.9% to 103.6% with the relative standard deviation (RSD) less than 3.9% (n=3). Under the optimized conditions, the enrichment factor (EF) for CLB could up to 62 folds. The presented method that combined the advantages of SPE and DLLME, had higher selectivity than SPE method and was successfully applied to the determination of CLB in tissue samples.
