Nine-Position Device

In summary, the results show that (3-lac-derived peptides were conclusively identified at subfemtomole per microlitre concentration. This sensitivity is comparable to the sensitivity achieved by nanoESI-MS,19 by sample delivery through fused silica capillaries, and from a simple micromachined device.7 

The next step was to demonstrate that multiple samples could be present on the device and successively delivered to the mass spectrometer with limited cross-contamination. To demonstrate the feasibility of this approach, standard 

At that point, we had achieved our goal to demonstrate that a micro-fabricated device can be coupled to a mass spectrometer and efficiently used for the rapid and sensitive identification of proteins separated by 2D gel electrophoresis. Although we toyed with the idea of more complex devices (we even designed a 42-position device which is still sitting on the author s desk), we quickly decided instead to move towards expanding the types of sample manipulation that could be done on and off the device. 

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Over the years, many different approaches based on these two basic principles have been developed.4 9 We decided to focus on developing an approach to transfer analytes by coupling capillary tubing with electrospray ionization devices. From this basic design principle, we were able to develop a simple three-position device for the analysis of proteomic samples by mass spectrometry.7,10 We developed this principle further into an automated nine-position device,6 and to perform frontal analysis separations of peptides.11 This chapter reviews these early developments in coupling microfabricated devices to mass spectrometers. 

Figure 2.5 Integrated analytical system. A nine-position microfabricated device was coupled to an ITMS instrument via a transfer capillary and a microESI ion source. The inner surface of the transfer capillary (15 cm long, 75 pm i.d., 150 pm o.d.) was derivatized with 3-aminopropylsilane. The etched channels were 30 pm deep and 72-73 pm wide. The diameter of the reservoirs was 1mm. The sample flow was controlled by an array of computer-controlled high-voltage relays which are also schematically represented. The software controlled the sample flow from the different reservoirs, the generation of MS spectra, the selection of potential peptides, the generation of MS-MS spectra and the matching of the MS-MS spectra against a protein sequence database. (Adapted with permission from Ref. 6).

Pinto et al. (2001) used 20 and 22 mm uncovered oesophageal Wallstents of 70 mm length in a series of 31 patients. In nine patients two stents were needed and in seven patients a percutaneous, transgastric approach was necessary, either because the delivery device was not long enough or the stent could not be properly positioned. In the other patients a peroral route with catheter technique under fluoroscopic guidance was used. Technical success was achieved... 

The Martindale device consists of up to nine testing positions, which are electrically driven. The guiding plate moves the specimen in its holder across the abrasive agent as shown in Fig. 12.16 in a Lissajous movement. The abrasive agent consists of a standardized woolen fabric. A counter keeps track of the number of abrasive cycles. The pressure on the specimen can be adjusted by weights put on top of the holder. The measured value either represents the number of cycles to cause a hole in the fabric, or it is preset to a certain value and the surface is assessed visually after this number of cycles was completed. 

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