Plate spotter

Preparation of TLC Plates The Plate Spotter Spotting the Plates Developing a Plate Visualization Interpretation Multiple Spotting Preparative TLC... 

The spotter is the apparatus used to put the solutions you want to analyze on the plate. You use it to make a spot of sample on the plate. 

Put the narrow end of a TLC spotter to a drop coming off of the column. The drop will rise up into the tube. Using this loaded spotter, spot, develop, and visualize a TLC plate with it. Not only is this more... 

Another interface commonly used for connecting HPLC to a mass spectrometer is not a true in-line interface. It is a robotically controlled spotter plate system for collecting samples from the HPLC to be injected into the MALDI time-of-flight laser ionization mass spectrometer for analyzing proteins and large peptides. The effluent sample dropped in the plate well is mixed with an ionization matrix already present, solvent and volatile reagents are evaporated, and the plate is then placed into the injector target and blasted with a pulsed laser to volatilize and ionize sample into the atmosphere of the interface where it can be drawn into the mass spectrometer. 

Thin-layer chromatography plates (silica) and spotters... 

When direct spotting onto a thin layer plate is used, an automatic spotter is necessary 7). It utilizes six tubes which transfer the eluting solvent in a dropwise manner to the origin. The size of the spot is controlled by the flow of an inert gas from a manifold. Three standards and three unknowns are spotted onto a 20 x 20 cm plate. 

Similar to Menon, Patel et al. [26] also used MeOH to prepare standard and sample solution. Mobile phase was comprised of toluene ethyl ace-tate MeOH = 50 45 5 v/v. HPTLC silica gel 6OF254 was used as the stationary phase, which was developed in the chamber that previously saturated for 30 min with the mobile phase. After developed in the chamber, the HPTLC plate was then dried in the air, and analysis was conducted at 2 = 230 nm. LOD and LOQ value obtained were 23.15 and 70.15 ng/spot, respectively. The automatic spotter used was filled with 100 pL volume of standard solution. Percent accuracy attained was 98.53-99.23%. 

Using the spotter, spot a small amount of each solution about 0.5cm from the bottom of the plate, leaving a similar distance between each spot. The spots should be kept as small as possible, and you should take care to make sure that each of the spots is the same distance from the bottom of the plate (Fig. 9.15a). 

Figure 11.1. Pin tool for spotting DNA on a glass slide. Panel a shows a four-pin device acquiring DNA solution from a micro titer well plate. The DNA solution is printed onto a glass slide in panel b. The DNA identities, well positions, and the spot positions are determined in a pattern program used by the spotter arrayer.

The spotter is the apparatus used to put the solutions you want to analyze on the plate. You use it to make a spot of sample on the plate. Put the center of a melting point capillary into a small, blue Bunsen burner flame. Hold it there until the tube softens and starts to sag. Do not rotate the tube, ever. 

Put the narrow end of a TLC spotter to a drop coming off at the column. The drop will rise up into the tube. Using this loaded spotter, spot, develop, and visualize a TLC plate with it. Not only is this more sensitive, but also you can see whether the stuff coming out of the column is pure (see Chapter 26, Thin-Layer Chromatography ). You ll probably have to collect more than one drop on a TLC plate. If it is very dilute, the plate will show nothing, even if there actually is compound there. It is best to sample four or five consecutive drops. 

Autospotters. There are a wide variety of semiautomated and fully automated devices commercially available for spotting samples. These devices have improved the reproducibility of the technique as they can deliver exact volumes as precisely defined spots on the plate, thus removing the greatest source of error in quantitative work. In their simplest form a sample vial is presented by hand the sample is drawn into the syringe which is driven by a stepper motor and is then applied to the plate. More sophisticated, fully automated systems are available where the spotter is... 

The measurement of discrete droplet volumes is now pla5dng a more and more important role in various applications such as pipettes, drug dispensing systems, inkjet printer heads, and microarray biochip spotters. The purpose of dispensing is to deliver a certain amount of a liquid sample, buffer solution, or frequently used library compound from a storage vial or mother plate to a cultivation container, test tube, assay plate, or microarray chip for subsequent handling. Applications in this field today are showing a trend toward a decrease in the volume of liquid to be handled, a trend that is promoted by the common... 

HPTLC uses much finer (about 5 micron) particles and somewhat thinner layers (200 micron) than TLC. This leads to much less spreading on the plate. Smaller plates are used (10 x 10 cm as opposed to 20 x 20 cm) and this necessitates better sample application of smaller samples. This is best carried out with an automatic spotter rather than with a micro-syringe, and with a steady hand and eye. The qualitative and quantitative... 

A variety of manual spotters are available that are useful for applying 1-100 il of sample to a plate. The simplest of these devices are wooden applicator sticks, attenuated Pasteur pipets, and capillary tubes. For more precise delivery of sample, micropipets or microsyringes calibrated in microliters are recommended. 

Figure 7.13 illustrates the Camag Anticircular U-chamber. samples (24 or 48) are applied in an outer ring with a Nanomat spotter (Figure 5.5) or manually using a positioning block. Solvent is fed from a reservoir to a narrow circular channel in direct contact with the layer outside of the initial zones. Sorbent is scraped away outside of the channel so that solvent can only flow inward toward the center of the plate. Mobile phase is transferred by capillary action and is not... 

For compound addition, we use an acoustical spotter (Echo 550, Labcyte Inc), which dispenses nanoliter volumes of compound directly into the wells of a 384-well plate, which already contain cells and medium in most cases. An alternative for nanoliter transfers are pintools, which also directly transfer... 

---