Purification solid-phase

The use of ethyl acetate was suggested by Oszmianski and Lee (1990) to wash out phenolics other than anthocyanins. Finally, a relatively pure anthocyanin extract can be removed from the colnmn with acidified methanol (0.1% HCl). Anthocyanin extracts can be enriched in this way by use of solid phase purification, which is especially helpful for diluted samples such as biological samples. Two factors in the nse of these purification techniques are the stability of anthocyanins to the conditions nsed and the ease of anthocyanin recovery from the column. ... 

ESI-MS has emerged as a powerful technique for the characterization of biomolecules, and is the most versatile ionization technique in existence today. This highly sensitive and soft ionization technique allows mass spectrometric analysis of thermolabile, non-volatile, and polar compounds and produces intact ions from large and complex species in solution. In addition, it has the ability to introduce liquid samples to a mass detector with minimum manipulation. Volatile acids (such as formic acid and acetic acid) are often added to the mobile phase as well to protonate anthocyanins. A chromatogram with only the base peak for every mass spectrum provides more readily interpretable data because of fewer interference peaks. Cleaner mass spectra are achieved if anthocyanins are isolated from other phenolics by the use of C18 solid phase purification. - ... 

Colistin (COL) is a multicomponent antibiotic (polymyxins E) that is produced by strains of inverse Bacillus polymyxa. It consists of a mixture of several closely related decapeptides with a general structure composed of a cyclic heptapeptide moiety and a side chain acetylated at the N-terminus by a fatty acid. Up to 13 different components have been identified. The two main components of colistin are polymyxins El and E2 they include the same amino acids but a different fatty acid (216). A selective and sensitive HPLC method was developed for the determination of COL residues in milk and four bovine tissues (muscle, liver, kidney, and fat). The sample pretreatment consists of protein precipitation with trichloracetic acid (TCA), solid-phase purification on Cl 8 SPE cartridges, and precolumn derivatization of colistin with o-phthalaldehyde and 2-mercaptoethanol in borate buffer (pH 10.5). The last step was performed automatically, and the resulting reaction mixture was injected into a switching HPLC system including a precolumn and the reversed-phase analytical column. Fluorescence detection was used. The structural study of El and E2 derivatives was carried out by HPLC coupled with an electrospray MS. Recoveries from the preseparation procedure were higher than 60%. 

The advantages of heterogeneous solid phase in combinatorial chemistry, especially in terms of purification procedures, can be obtained also by solution-phase chemistry, using solid support assistance. The resin performs a specific function during the library synthesis and then is simply removed by filtration, leaving the pure library components in solution. A well-known adapted technique uses solid supported reagents or catalysts during a combinatorial synthesis, where the solid phase is filtered off and discarded after the reaction in which it was involved. A new application is represented by solid-phase purification, where one or more solid supports are added to trap the excess of... 

If the acidic methanol system (described in Section 3.1.2.) produces an unsatisfactory extraction, we would suggest extracting with 50% MeCN/0.1% TEA, then diluting 1 10 (v/v) in 0.1% TEA before solid-phase purification. Unlike the 10% TEA extracts, supernatants from acidic methanol and 50% MeCN/0.1% TEA extracts can be stored at 4 C after addition of 2-MTE (to prevent sample oxidation see Note 1) prior to solid phase extraction. 

Among the purifications formats evaluated for their potential in MALDl-TOF-MS analysis, spin-columns with size separation capabilities as well as solid-phase purification systems such as reversed-phase beads/columns and streptavidin-coated beads, have proved very efficient [130-134]. The assay formats described in the following section very often rely on one of these purification formats. 

Kozutsumi, D. Kawashima, A. Adachi, M. Takami, M. Takemoto, N. Yonekubo, A. Determination of docosahex-aenoic acid in milk using affinity solid phase purification with argentous ions and modified thin layer chromatography. Inti. Dairy J. 2003,13 (12), 937-943. 

Spottke, B., Gross, J, Galla, H.J., Hillenkamp, F. (2004) Reverse Sanger sequencing of RNA by MALDI-TOF mass spectrometry after solid phase purification. Nucleic Acids Res., 32(12), e97. 

Only for dietary supplements or processed food samples, extraction of anthoeyanins followed by solid phase purification with subsequent analysis by HPLC with UVA/ IS detection is performed as first level analysis. The matrix in those samples is complex and may include synthetic colorants in accordance with applicable food legislation, hence simple UVA IS analysis would yield most certainly erroneousness results. At this stage of analysis a decision is necessary on whether or not HPLC/MS analysis has to be performed. HPLC/ MS is powerful for the confirmation of anthocyanin structures but seldom useful for quantification as the calibration is complicated and robustness is low. 

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