Surface-assisted methods

Surface Assisted Methods for the Synthesis of Graphene-Tj pe Structures. 149... 

An application of surface-assisted laser desorption-ionization (SALDI) method for practical, ultrahigh sensitivity detection of aromatic amines by GC-MS is reported. The prototype analytical device for trace detection of different organic compounds is created. 

Matrix-assisted laser desorption/ionization (MALDI) is widely used for the detection of organic molecules. One of the limitations of the method is a strong matrix background in low-mass (up to 500-700 Da) range. In present work an alternative approach based on the application of rough matrix-less surfaces and known as surface-assisted laser desoi ption/ionization (SALDI), has been applied. 

A novel, electrochemically assisted method of obtaining semiconductor quantum dots supported on a surface has been introduced by Penner and his group [123], It comprised a hybrid electrochemical/chemical (E/C) process consisting of electrochemical deposition followed by chemical modification and it was described as a general, rapid, and low-cost solution-phase method for synthesizing supported Q-dots of metal salts. 

As evident from Scheme 7.13, most modern ionisation techniques have been used for TLC-MS, and no single ionisation method is used exclusively with TLC-MS. Various ionisation methods may be applied that avoid the need to evaporate the sample into an El or Cl source these are based in particular on sputtering (FAB, SIMS) or laser desorption. Several sputtering methods of ionisation do not require the use of a liquid matrix, e.g. TLC-SIMS [797], Recent developments include the use of matrix-assisted laser desorption ionisation (MALDI) and surface-assisted laser desorption ionisation (SALDI). It is obvious that TLC-MS is complemented with TLC-MS11 [800] and TLC-HRMS techniques. Table 7.82 lists the general characteristics of TLC-MS. 

The ionization methods reported for IMS included MALDI [41,76-80], Secondary Ion Mass Spectrometry (SIMS) [19, 81-86], Matrix-enhanced (ME)-SIMS [87, 88], Desorption Electrospray Ionization (DESI) [89-99], Nanostructure Initiator Mass Spectrometry (NIMS) [100-102], Atmospheric Pressure Infrared MALDI Mass Spectrometry (AP-IR-MALDI-MS) [103], Laser Ablation-inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) [104-106], Laser Desorption Postionization (LDPI) [107], Laser Ablation Electrospray Ionization Mass Spectrometry (LAESI) [108, 109], and Surface-assisted Laser Desorption/ioniza-tion Mass Spectrometry (SALDI) [110-112], Another method was called probe electrospray ionization (PESI) that was used for both liquid solution and the direct sampling on wet samples. 

Ultrasound-assisted methods are usually less robust than microwave-assisted ones because, as noted by Cencic-Kobda and Marcel [51], ageing of the US probe surface can alter the leaching efficiency. 

Mesoporous ceria and ceria-zirconia powders with high surface area have also been prepared using a surfactant-assisted method to prepare catalysts containing Ce02... 

Currently, multiple-component, internal gas-assisted and decorative processes are being used more and more frequently in combination with thin-wall techniques. A good example of this is the trend to highly individualized cell phone designs. Decorative processes such as inmold decoration or insertion of preformed, printed foils makes variable coloration of even small run volumes possible. The internal gas-assisted method is used for example to reduce the mass of thick-walled parts and to avoid sink marks minimization of warpage is thus a primary requirement for thin-walled parts. A wide variety of functions can be realized by means of the multiple-component technique, including seals, napped surfaces, improved antishp properties and functional elements, some of which are now still being mounted in complex and expensive additional steps. 

Chemical Chemically resistant to degradation/corrosion, pH stability High chemical purity Possible sp carbon shells Numerous oxygen-containing groups on surface Ease of surface functionalization (chemical, photochemical, mechanochemical, enzymatic, plasma- and laser-assisted methods) Radiation/ozone resistance Large number of unpaired electrons on the surface... 

Nanocarving Well-defined nanostructured devices with high surface area Electric field-assisted methods Available only for a limited number of materieils... 

Surface-assisted laser desorption/ionization is a laser-induced ionization method developed in parallel to the more well-known matrix-assisted laser desorption/ionization (MALDI) method. Using inorganic materials as energy-mediating media, it has been exploited as a possible alternative to MALDI, especially in small molecule detection (1—4). The most successful SALDI substrate was reported by Siuzdak and coworkers, in which a silicon surface of mesoporous features was used, commonly termed as... 

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