We describe a method, filter-aided sample preparation (FASP), which combines the advantages of in-gel and in-solution digestion for mass spectrometry-based proteomics. We completely solubilized the proteome in sodium dodecyl sulfate, which we then exchanged by urea on a standard filtration device. Peptides eluted after digestion on the filter were pure, allowing single-run analyses of organelles and an unprecedented depth of proteome coverage.
► We review recent applications of graphene-based materials in SPE and SPME. ► We review recent applications of graphene-based materials in MALDI-MS. ► We discuss challenges and perspectives of graphene-based sample preparation. As a new member of the carbon family, graphene has fascinated the scientific community since its discovery. Recently, graphene also exhibited great potential to be an adsorbent in analytical sample preparation due to its exceptional properties (e.g., large surface area, π-electron-rich structure, and good thermal and chemical stability). In this article, we review the recent applications of graphene and graphene-based materials in solid-phase extraction and solid-phase microextraction, and other sample-preparation techniques. We also cover the use of graphene as extractor and matrix in matrix-assisted laser desorption/ionization mass spectrometry. Finally, we discuss possible challenges and future perspectives in this rapidly developing field.
The presence of cell-free microRNAs (miRNAs) has been detected in a range of body fluids. The miRNA content of plasma/serum in particular has been proposed as a potential source of novel biomarkers for a number of diseases. Nevertheless, the quantification of miRNAs from plasma or serum is made difficult due to inefficient isolation and lack of consensus regarding the optimal reference miRNA. The effect of haemolysis on the quantification and normalisation of miRNAs in plasma has not been investigated in great detail. We found that levels of miR-16, a commonly used reference gene, showed little variation when measured in plasma samples from healthy volunteers or patients with malignant mesothelioma or coronary artery disease. Including samples with evidence of haemolysis led to variation in miR-16 levels and consequently decreased its ability to serve as a reference. The levels of miR-16 and miR-451, both present in significant levels in red blood cells, were proportional to the degree of haemolysis. Measurements of the level of these miRNAs in whole blood, plasma, red blood cells and peripheral blood mononuclear cells revealed that the miRNA content of red blood cells represents the major source of variation in miR-16 and miR-451 levels measured in plasma. Adding lysed red blood cells to non-haemolysed plasma allowed a cut-off level of free haemoglobin to be determined, below which miR-16 and miR-451 levels displayed little variation between individuals. In conclusion, increases in plasma miR-16 and miR-451 are caused by haemolysis. In the absence of haemolysis the levels of both miR-16 and miR-451 are sufficiently constant to serve as normalisers.
► Nanomaterials have shown excellent extraction ability for various compounds. ► Metallic, silica and carbon nanomaterials used for sample clean-up. ► Metallic, silica and carbon nanomaterials used for preconcentration. ► Solid-phase and liquid-liquid extraction can use nanomaterials. ► Microextraction and filtration can use nanomaterials. The article presents recent applications of nanomaterials (metallic, silica and carbon-based) in sample-preparation procedures for sample clean-up and preconcentration of the analytes. Solid-phase extraction, microextraction and filtration techniques reported in 2010-11 are presented and discussed.
Functionalized magnetic nanoparticles have attracted much attention in sample preparation because of their excellent performance compared with traditional sample-preparation sorbents. In this review, we describe the application of magnetic nanoparticles functionalized with silica, octadecylsilane, carbon-based material, surfactants, and polymers as adsorbents for separation and preconcentration of analytes from a variety of matrices. Magnetic solid-phase extraction (MSPE) techniques, mainly reported in the last five years, are presented and discussed.
► We discuss synthesis and characterization of functionalized magnetic materials. ► Functionalized magnetic materials applied to biological macromolecules of proteome. ► Applications of functionalized magnetic materials to food-contaminant analysis. Functionalized magnetic materials (FMMs) have been widely used in analytical chemistry. For sample preparation, FMMs show many advantages including easy surface modification, easy operation and high extraction efficiency. In this review, we describe the recent advances in FMMs in sample preparation. We first discuss their synthesis and characterization. We then focus on their application to enrichment of biological macromolecules of the proteome and contaminants in foods. Finally, we outline the prospects for FMMs in sample preparation.
► Recent applications of molecularly-imprinted polymers (MIPs) to sample preparation. ► We highlight new formats and microextraction methods for sample preparation. ► Trends in techniques with molecularly-imprinted polymers (MIPs) in sample preparation. Molecularly-imprinted polymers (MIPs), possessing tailor-made recognition sites, can specifically rebind to a target molecule in preference to analogous compounds. Molecular-imprinting technology is a powerful tool in the development of highly selective analytical methods. MIPs are especially good candidates as adsorbents for sample preparation, due to their high selectivity and their ability to pre-concentrate the analytes from a complex sample matrix. In this article, we review and discuss the recent applications of MIPs to sample preparation. We briefly discuss the principle and the synthesis of MIPs. We critically evaluate novel applications of MIPs in different formats, including solid-phase extraction, solid-phase microextraction, stir-bar sorptive extraction, and magnetic beads. We especially highlight new formats and microextraction methods. We then discuss the problems and the future expected trends in these research areas.
Biological and pharmaceutical samples represent formidable challenges in sample preparation that hold important consequences for bioanalysis and genotoxic impurity quantification. This Feature will emphasize significant advances toward the development of rapid, sensitive, and selective sample preparation methods.