RESUMO
BACKGROUND: Determining metals in complex biological samples, such as milk, typically involves dry or wet decomposition. However, these techniques have limitations, including low selectivity, risk of contamination, and the use of large reagent volumes. To solve these problems, solid-phase extraction (SPE) using multifunctional sorbents has been extensively explored. In this context, this work proposed synthesizing a new restricted double access ionic imprinted polymer (RAIIP-BSA), for online SPE and determination of Cu2+ from untreated milk samples via flow injection analysis and flame atomic absorption spectrometry (FIA-FASS). RESULTS: Firstly, the polymer was obtained by bulk polymerization using Cu2+ as a template, 4-vinyl pyridine as a functional monomer, and glycidyl methacrylate as a hydrophilic comonomer. Subsequently, it was covered with bovine serum albumin, creating the restricted double access barrier. The obtained material could exclude 97 % of the proteins from milk samples. RAIIP-BSA was chemically and physically characterized. The main extraction variables were optimized via multivariate optimization. The method showed good figures of merit, such as linearity ranging from 0.05 to 1.0 mg L-1, LoD and LoQ of 0.03 and 0.05 mg L-1, intra- and interday precision ranging from 0.73 to 4.14 % and 0.16-3.68 %, and an intra- and interday accuracy ranging from 97.0 to 115.0 % and 103.0-119.0 %, respectively. SIGNIFICANCE: The developed method demonstrates the effective extraction of Cu2+ from untreated milk samples, exhibiting selectivity, high extraction capacity, prolonged sorbent (RAIIP-BSA) durability, simplicity, and swift operation. This method holds promise as an alternative to conventional metal analysis approaches in complex matrices.
Assuntos
Cobre , Impressão Molecular , Animais , Cobre/química , Leite/química , Impressão Molecular/métodos , Polímeros/química , Extração em Fase Sólida/métodosRESUMO
This paper describes, for the first time, the use of restricted access carbon nanotubes (RACNTs) in the analysis of tetracyclines from milk samples, in a multidimensional liquid chromatographic system. Milk samples were initially acidified and centrifuged, and then the supernatant was directly analyzed in a column switching system in backflush configuration employing an extraction column of RACNTs. The sorbent was able to exclude all the remained proteins in less than 2.0min. The method was linear from 50 to 200µgL-1 and the coefficients of determination (r2) were 0.997, 0.992, 0.994 and 0.998 for oxytetracycline (OXI), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DOX), respectively. The analytical range included the maximum residue limits established by the regulatory agency.
Assuntos
Cromatografia Líquida , Nanotubos de Carbono/química , Tetraciclinas/isolamento & purificação , Animais , Leite/química , Tetraciclinas/análise , Tetraciclinas/químicaRESUMO
The determination of organic and inorganic analytes from biological samples need efficient sample preparation procedures in order to capture the analyte in a media with many macromolecules, which can cause analytical errors and problems with the instruments. Thus, "intelligent" sorbents, called restricted access materials (RAMs), have been widely used with these samples, due to their ability to retain analytes and exclude macromolecules. These materials have been obtained by modifying the external surfaces of conventional sorbents (e.g. polymers, carbon nanotubes, active carbon, and silica-based materials) with hydrophilic groups (chemical barrier), as well as by the presence of small pores (physical barrier) accessible only to low molecular weight molecules. Supramolecular solvents (SUPRAs) have also been used as RAMs, due to their abilities to exclude proteins according to size or through precipitation with the solvents. Therefore, due to the relevance of these materials, this review presents an overview of the most recent advances in obtaining RAMs based on silica, polymers, carbon nanotubes, (activated) carbon, and solvents, as well as their applications in biological sample preparation.
Assuntos
Carvão Vegetal , Nanotubos de Carbono , Polímeros , Dióxido de Silício , Solventes , Manejo de Espécimes/métodos , Interações Hidrofóbicas e Hidrofílicas , Substâncias MacromolecularesRESUMO
In-tube solid-phase microextraction (in-tube SPME) coupled with high performance liquid chromatography (HPLC) or liquid chromatography coupled to mass spectrometry (LC-MS) successfully determines drugs or biomarkers in biological samples by direct sample injection or by simple sample treatment. This technique uses a capillary column as extraction device. Several capillaries (wall-coated open tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with unique phases have been developed and evaluated, aiming to improve the efficiency and selectivity of the in-tube SPME-LC technique. This review describes new developments and applications occurred in recent years, and discusses future trends with emphasis on new extraction devices and current technology used for the synthesis of selective sorbents for bioanalysis, such as (i) polypyrrole, (ii) restricted-access materials, (iii) immunosorbents, (iv) molecular imprinting polymers, (v) monolithic polymers, and (vi) bi-functional materials.