RESUMEN
A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides was firstly prepared by combining surface molecular imprinting technique with the sol-gel process. Methyl-3-quinoxaline-2-carboxylic acid (MQCA) was used as template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilicane as cross-linker. The MIP was characterized by Fourier transform infrared and evaluated through static adsorption experiments. The results indicated that MIP had high adsorption capacity, fast binding kinetics for MQCA, and the polymer showed a high degree of cross-reactivity for quinoxaline-2-carboxylic acid (QCA). The MIP was then applied as a selective sorbent in an online solid phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). For a 50-mL sample solution, enrichment factors of 1,349 and 1,046 for QCA and MQCA, respectively, and limits of detection (S/N=3) of 0.8 and 2 ng L(-1) for QCA and MQCA, respectively, were obtained (corresponding to 0.02 and 0.04 ng g(-1) in solid samples for final 100 mL of sample solutions of 5 g of pork). The sample preparation protocol was simplified and only included one step extraction with acetonitrile (MeCN) after the release of target analytes through acidic hydrolysis without further sample cleanup. The new MIP-SPE-HPLC method was successfully applied to the quantification of trace QCA and MQCA in pork muscle with good recoveries ranging from 67% to 80% and RSD below 8%.
Asunto(s)
Carne/análisis , Impresión Molecular , Músculos/química , Polímeros/química , Quinoxalinas/aislamiento & purificación , Gel de Sílice/química , Adsorción , Animales , Cromatografía Líquida de Alta Presión , Polímeros/metabolismo , Extracción en Fase Sólida , PorcinosRESUMEN
In the present paper, a hapten of methamidophos was synthesized and conjugated with KLH by active ester method, thus the first artificial antigen was obtained. By diazotization method methamidophos conjugated with BSA, and the second artificial antigen was obtained. The synthesized haptens were characterized by MS, IR and 1H NMR, and the two artificial antigens were determined by the method of IR spectrum. The result implied that both the artificial antigens have absorbance peaks of hapten and protein, indicating that they were prepared successfully. This could provide evidence that the method of IR spectrum can be used to determine whether the artificial antigens are synthesized successfully.