BcMag™ C18(Reversed-Phase) magnetic Beads are uniform superparamagnetic resins containing hydrophobic C18alkyl groups on their surface. The beads are specifically designed for quickly purifying, desalting, and concentrating femtomolar to the picomolar scale of peptides or proteins, manually or automatically, without laborious repeat pipetting and centrifugation. BcMag™ C18Magnetic beads are recommended for purification, desalting, and concentration of low molecular weight proteins or peptides. For low to intermediate molecular weight proteins, BcMag™ C-8 magnetic beads are preferred. BcMag™ C-4 magnetic beads are most suitable for larger molecular weight proteins and peptides. However, the three types of beads can be used interchangeably in many cases.

What is C18?

Linear alkylsilane phases include C18, C8, and C4. C18 is octyl-decyl silane with 18 carbons linked to magnetic silica beads. As a result, they have more carbons and a longer carbon chain than C8 (8 carbons) or C4 (4 carbons).

Because of the extra carbons, C18 has a larger surface area across which the mobile phase must traverse. It gives the bound phase, and the elutes greater interaction time. As a result, the sample elutes more slowly and with greater separation.

C8 (also known as octyl), on the other hand, has a shorter retention duration and sharper peaks. Small organic chemicals benefit from these column types, but long-chain fatty acids and complex molecules benefit from C18s.

The beauty and simplicity of a C18 stationary phase are that it provides a direct hydrophobic interaction. The hydrocarbon can bind and hold solutes in the mobile phase as they travel through the beads via a weak hydrophobic (and van der Waal force) interaction. With this information, the task becomes very clear: to retain molecules on C18 resins, the chemical must become as neutral or hydrophobic as possible. Nothing could be done with analytes that are already neutral or have no probability of getting charged. However, we can use a buffer to limit the extent of their charge state for weakly acidic and basic substances. Another chemical property that can be employed here is pKa (and pKb). Weak acids and bases exist in two states in solution: neutral and deprotonated (acids) or protonated (bases) (bases). At a particular pH, the concentrations of these two conjugate forms are identical.

C18 Hydrophobic magnetic beads

Bioclone hydrophobic magnetic resins are designed as uniform magnetic beads grafted with a high density of hydrophobic ligands on the surface. The hydrophobic magnetic beads are rigid polymeric beads with covalent surface chemistries, allowing easier handling and packing while providing more excellent physical and chemical stability—resulting in a robust production process. The beads replace time-consuming, difficult, and expensive chromatographic techniques such as agarose, cellulose, Sepharose, Sephadex-based columns, or resins. The hydrophobic magnetic beads are manufactured using nanometer-scale superparamagnetic iron oxide as core and entirely encapsulated by a high purity silica shell, ensuring no leaching problems with the iron oxide. The pure inert silica makes less nonspecific binding. The beads are much smaller (1, 2.5, and 5 μm diameter) in size and are non-porous, which exhibit larger surface area, less nonspecific binding, and higher resolution than porous supports.

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MSDS

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General Reference

1.

Lauber MA, Koza SM, McCall SA, Alden BA, Araneta PC, Fountain KJ. High-resolution peptide mapping separations with MS-friendly mobile phases and charge-surface-modified C18. Anal Chem. 2013 Jul 16;85(14):6936-44.

2.

Field JK, Euerby MR, Haselmann KF, Petersson P. Investigation into reversed-phase chromatography peptide separation systems Part IV: Characterisation of mobile phase selectivity differences. J Chromatogr A. 2021 Mar 29;1641:461986.

3.

Liang Y, Wang C, Liang Z, Zhang L, Zhang Y. C18-Functionalized Amine-Bridged Hybrid Monoliths for Mass Spectrometry-Friendly Peptide Separation and Highly Sensitive Proteomic Analysis. Anal Chem. 2022 Apr 26;94(16):6084-6088.

4.

Wang Q, Ye M, Xu L, Shi ZG. A reversed-phase/hydrophilic interaction mixed-mode C18-Diol stationary phase for multiple applications. Anal Chim Acta. 2015 Aug 12;888:182-90.

5.

Hernandez-Hernandez O, Quintanilla-Lopez JE, Lebron-Aguilar R, Sanz ML, Moreno FJ. Characterization of post-translationally modified peptides by hydrophilic interaction and reverse-phase liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry. J Chromatogr A. 2016 Jan 8;1428:202-11.

6.

Zhou, N. E., Mant, C. T., Kirkland J. J., and Hodges R. S. (1991) Comparison of silica-based cyanopropyl and octyl reversed-phase packings for the separation of peptides and proteins. J. Chromatogr.548, 179–193.

Bioclone的BcMag™NHS激活的磁珠是均匀的，基于二氧化硅的超顺磁珠，表面涂有高密度NHS（N-羟基琥珀酰亚胺）官能团。珠子用于特异性地缀合含伯胺的配体（图1），因此在偶联之前不需要保护配体中的其他活性基团。耦合快（室温pH 6.5–9 15–30分钟，4°C 4小时）。BcMag™NHS激活的磁珠最适合与大蛋白结合。建议使用BcMagTM长臂（17 atome）NHS激活的磁珠来缀合小肽，因为长臂（21原子）亲水性接头可以减少空间位阻。