Multichannel plates , fluorescence

A multichannel plate (MCP) is a type of CDEM in which a series of microchannels on a disk-shaped device are coated with an electron-emissive material to generate 10 to 10" amplification as the electrons cascade through the microchannels. MCPs can be stacked to increase amplification or focused onto a fluorescent surface for ion-beam imaging. Because of the short electron pulse widths ( 1 ns) obtained with MCPs, they are the ion detector of choice for time-of-flight mass spectrometers. 

The //PLC system described in this chapter is equipped with 24 parallel columns for liquid chromatography, each with its own sample introduction port and exit port for connection to detectors of choice (UV absorbance and/ or fluorescence). Flow from a binary solvent delivery system is divided evenly across 24 channels and results in 1/24 of the programmed pump flow rate through each column (i.e., total flow of 300 /zL/ min will produce a flow of 12.5 /zL/ min in each column). Samples are introduced to the columns by a multichannel autosampler configured to sample from either 96-or 384-well SBS standard plates. Figure 6.2 depicts a general view of the system. 

TCSPC is Ulnstrated in Fig. 3a. In addition to a mode-locked laser for pnlsed excitation and a detector with high time resolntion (nsnally a micro-channel plate photomultiplier tube capable of time-resolution of 20-30 ps), the required instrumentation inclndes constant-fraction discriminators to generate electrical pnlses triggered by fluorescence photons and by the reference (the excitation pulse), a time-to-amphtude converter or other device to measnre the time lag between reference and flnorescence connts, and a multichannel scaler to accumnlate... 

As manual, multichannel pipeting devices and plate-based detection systems became staple tools in the modem discovery laboratory, bioassays for moderate throughput have been developed in a wide variety of formats. The flexibility of these detection devices allowed assays that utilize visible-, fluorescence-, luminescence-, and radioactive-based readouts. Manual pi-... 

A multichannel detector for In-situ analysis of fluorescent materials on TLC plates was investigated (26). The optical system was designed to obtain a fluorescence spectrum from each position along the elution axis of a one-dimensional plate without the mechanical scanning. By use of tetraphenylporphlne and octaethylporphine it can be shown how overlapping spots can be resolved into their components. 

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