Prestructured sample supports

An alternative approach is to reduce the sample spot size close to the diameter of the laser spot. One way to do this is to apply a small volume of the sample solution (typically a few nanoUters) onto a MALDI target plate. Unfortunately, this sample preparation technique requires state-of-the-art Uquid-handling systems. 

An alternative, less-expensive method to produce disposable sample supports has been described by Owen et al. [80], in which blank stainless-steel plates were coated with Teflon and Scotchgard hydrophobic coatings. An enhancement in detection sensitivity correlated with reduced spot sizes when using the hydrophobic coatings, which could be removed by cleaning and re-applied between uses [80]. 

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E. Nordhoff, M. Schurenberg, G. Thiele, C. Lubbert, K.-D. Kloeppel, D. Theiss, H. Lehrach, and J. Gobom. Sample Preparation Protocols for MALDI-MS of Peptides and Oligonucleotides Using Prestructured Sample Supports. Int. J. Mass Spectrom., 226(2003) 163-180. 

A Novel Approach Using MALDI-TOF/TOF Mass Spectrometry and Prestructured Sample Supports (AnchorChip Technology) for Proteomic Profiling and Protein Identification... 

Nordhoff, E., Schuerenberg, M., Thiele, G. Lubbert, C., Kloeppel, K.-D., Theiss, D., Lehrach, H., and Gobom, J. (2003) Sample preparation protocols for MALDI-MS of peptides and oligonucleotides using prestructured sample supports. Int. J. Mass. Spectrom. 226, 163-180. 

Fig. 4 CHCA affinity MALDI sample preparation of peptides. This technique takes advantage of prestructured sample supports (hydrophilic sample anchors surrounded by a hydrophobic support) and the observation that microcrystalline CHCA has a high RP affinity and binding capacity for peptides. It integrates sample purification and concentration in the last step of the sample preparation. Typically 0.5-2.0 p,L of acidified sample solution (pH 1.5-2.5) is deposited onto one matrix spot measuring 400, 600, or 800 (jtm in diameter. Depending on the pimity and concentration of the samples, they are either allowed to dry at ambient temperature (option 1) or removed after a defined incubation time, e.g., 3 min (option 2). In either case, all samples are washed once or multiple times with a larger volume of acidified water (3-8 xL) before they are analyzed. AH these steps can be performed manually or automated using a pipetting robot as shown on the left. If the samples contain a lot of undesired contaminants that are difficult to completely wash away, option 2 is preferred. If their concentration is very low, the affinity purification yields benefit from longer incubation times because the samples volumes continuously shrink over time until all solvent is evaporated. Therefore, if the contaminants can easily be washed away, option 1 is recommended because it provides maximum sample concentration and is easier to perform than option 2...

Lehrach, H., Nordhoee, E. (2000). Prestructured MALDI-MS sample supports. Arud. Chem. 72, 3436-3442. 

M. Schuerenberg, C. Luebbert, H. Eickhoff, M. Kalkum, H. Lehrach and E. Nordhofif, Prestructured MALDl-MS sample supports. Anal. Chem., 2000, 72(15), 3436-3442. 

Schuerenberg M, Luebbert C, Eickhoff H, et al (2000) Prestructured MALDI-MS sample supports. Anal Chem 72(15) 3436-3442... 

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