Micro-SPE

Y. Shen, N. Tolic, C. Masselon, L. Pasa-Tolic, D. G. Camp, K. K. Hixson, R. Zhao, G. A. Anderson, and R. D. Smith. Ultrasensitive Proteomics Using High-Efficiency On-Line Micro-SPE-NanoLC-NanoESI MS and MS/MS. Anal. Chem., 76(2004) 144-154. 

Shen, Y., Tolic, N., Masselon, C., Pasa-Tohc, L., Camp, D. G., Hixson, K. K., Zhao, R., Anderson, G. A., and Smith, R. D., Ultrasensitive proteomics using high-efficiency on-line micro-SPE-NanoLC-NanoESI MS and MS/MS, Analytical Chemistry 76(1), 144-154, 2004. 

Figure 3.17 Layout and dimensions of the integrated SPE-NCE with (b) photograph of the multilayer device (c) and (d) micrograph and diagram of the packed micro-SPE column between two shallow weirs [121].

Desalting by reversed-phase HPLC (see Subheading 2.4.) or SEC or micro-SPE onto Ci 8 Zip-Tip (used the conditions recommended by the manufacturer Millipore). The recently developed magnetic beads from Bruker may represent a fast and economical alternative. 

Perform immediately the purification of the digest mixture on a reversed-phase column or by fast desalting by micro SPE using a Ci8 Zip-Tip (Millipore). 

A different application of SPE which needs 100-200 pi of sample has recently been successfully applied to plasma. Micro SPE (pSPE) followed by HPLC-MS/ MS was used by Napoletano et al. [67] to determinate amphetamine, methamphet-amine, MDA, MDE, MDMA, cocaine, BEG, mescaline, ketamine, PCP, psilocy-bine in plasma. In this method 180 pi of plasma were submitted to slight PPT with 20 pi of methanol containing ISTD, 100 pi of supernatant were then collected and passed through C18 tips, adapted to automatic pipettes. Validation results showed pSPE allows to reduce matrix effect (<10 %) keeping satisfactory recoveries. pSPE represent a simple, fast and reliable procedure with extremely reduced solvent consumption it will be discussed in more detail below in its other applications. 

Determination of illicit drugs in urine and plasmaby micro-SPE followed by HPLC-MS/ MS. Chromatographia. doi 10.1007/sl0337-011-2156-6... 

Following cell lysis, DNA extraction, purification, and preconcentration are usually achieved by microsolid phase extraction (micro-SPE) devices. This step is essential in order to purify and isolate the genomic materials from other cellular components, contaminants, and chemicals introduced in the cell lysis step that might potentially interfere with downstream enzymatic reactions. In addition, the nucleic acids may be enriched in this phase of the processing strategy to preconcentrate the targets to a level that is amenable for further downstream processing. 

A variety of well-established macroscale SPE methods for nucleic acid extraction have been successfully transferred to microscale devices [10, 31-57]. Although the physical principles of these methods may be different (e.g., chaotropic interactions, electrostatic interactions, affinity interactions, etc.), micro-SPE protocols typically consist of three steps (1) selective adsorption of nucleic acids onto a solid phase (2) removal of contaminants by a washing step and (3) elution of the preconcentrated nucleic acids from the solid support using water or a low salt buffer [31]. Like their macroscale counterparts, micro-SPE devices possess a loading level of target material that is dependent upon the available surface area within the extraction bed and, thus, are manufactured either by packing the solid phase... 

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