MALDI-MS techniques

In contrast to established MALDI-MS techniques, DIOS-MS is a comparatively new technique. However, over the last five years, it has been gaining steadily more attention and promising results have already been obtained in all those cases, where interference from classic MALDI matrices needed to be avoided. Owing to the fact that DIOS-MS is still a juvenile technique, it is hard to predict future developments, but especially in the field of silicon modifications further promising developments can be foreseen, accompanied by new applications. 

This unit describes procedures for extraction, purification, and identification by MALDI-MS of fiavonol glycosides from a plant source. The extraction and purification protocols are not meant to be comprehensive, but rather to offer guidelines for sample preparation prior to a MALDI-MS analysis. The MALDI-MS technique is suggested as a complement to other analytical methods such as HPLC or NMR. Its strength lies in the ability to rapidly screen a number of samples for the presence of fiavonol glycosides, which can be identified on the basis of their molecular weights. 

Literature analysis and our preliminary experiments with proteins, carbohydrates and other molecules deposited on the surface of nanosilicas suggest that newly developed MALDI MS techniques, in particular Surface MALDI MS, can be adopted as a powerful new tool for surface analysis. Unique capabilities that surpass established techniques in surface analysis of biomaterials using these newly developed methods is an exciting development. 

A first interest of MS when used in combination with microfabricated structures, or at the outlet of microfluidic devices, is the match in the volume of liquid handled. A typical MS analysis requires less than 1 pL of liquid, for ESI-MS as well as for MALDI-MS techniques. When working with a continuous flow of liquid and ESI-MS, the MS performance is even more enhanced for flow rates down to 50-100 nL min-1 the lower the flow rate, the better the MS analysis. This flow-rate range corresponds to flow-rate values observed in microfluidic devices. Consequently, the technique of MS is easily scalable and exhibits an enhanced response when the sample size is decreased. This is not the case for instance for other detection techniques, such as UV absorbance or amperometry these two techniques require large detection area or volume, which is the opposite of the quest of microfluidics. This first advantage of MS compared to other technique goes together with its high sensitivity. 

Insulin binding to the G-quadruplex formed by a sequence of two of the tandem ILPR repeats, hereinafter referred to as ILPR2, was studied using both the affinity CE and affinity MALDI-MS techniques described above. It is important to note that the surface-immobilized DNA that is intrinsic to both capture schemes is a more realistic model for G-quadruplexes in genomic DNA than would be provided by free DNA in solutions, since G-quadruplexes in genomic DNA would be anchored in the chromosomal strand. 

Since the introduction of a new type of mass spectrometer [28, 53] capable of analysing intact proteins and polymers up to 100.000 Da, great interest has been shown for techniques allowing the analysis of proteins. Basically, the MALDI-MS technique consists of mixing the analyte (organic polymers, proteins or peptides)... 

This GPC-MALDI-MS technique has several advantages over the traditional method of using polymer standards to calibrate GPC. The MALDI approach does not rely on the availability of polymer standards. This is very important for characterizing newly developed polymeric systems where no standards of accurate masses are available. MALDI-MS should be more accurate in determining the polymer molecular mass to calibrate the GPG chromatogram, compared to the use of polymer standards, unless the polymer standards, if available, are mass-analyzed by MALDI-MS beforehand. In GPC-MALDI-MS, polymer mixtures can be analyzed, because the mass spectral data provide another dimension of differentiating individual polymers based on their mass characteristics. 

This section discusses MS techniques for biological threat detection. Currently, the major methods to detect biological pathogens and toxins by MS involve the use of LC-MS and matrix-assisted laser desorption/ ionization (MALDI)-MS techniques. 

TABLE 15.1 TLC Combined with MALDI-MS Techniques for Identification of Lipids, Gangliosides, Drugs, and Other Organic Compounds O O 3 3 ... 

Some sulfur compoimds such as alkylphenol ethoxysulfonate surfactant formulations can be detected by MALDI-MS. Benomar et al. [19] concluded that the MALDI-MS technique has been shown to be an useful tool for the analysis of these compounds. 

Matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS) MALDI-MS technique enables ionization a broad range of materials, with high sensitivity, broad mass range of materials, fast sample preparation, and the absence of fragmentation. 

---