List mode data acquisition

The number of files per disk is given as the number of samples (of 10,000 cells each) whose list mode data (4-parameter/ 1024-channel resolution) after acquisition can be stored to media of the indicated size. The capacity in bytes of the different media is representative but will vary with the formats of different computing systems. Similarly, different acquisition software will require more or less extra storage space for the housekeeping information that is stored with each sample. Prices of media are illustrative, but will vary considerably from place to place and over time. 

The scanner is designed to recognise coincidences where events occur in two opposing buckets within a resolving time of 12 ns. In normal operation, only coincidences between two elements in the same ring or adjacent rings (of the 8) were accepted, but for PEPT use this restriction was removed. The data acquisition system of the scanner was also modified so that coincidence data is recorded in list mode with time stamps at 1 ms intervals. 

HPLC was performed using Waters 600S solvent delivery system (Waters, Milford, MA, U.S.A.). 2487 UV dual channel detector of Waters was used and injector (20 fit sample loop) from Rheodyne. The data acquisition system was Millenium (Waters). Water filtered 1 Milipore ultra-pure water system (Milipore, Bedford, MA, USA). The wavelength was fixed at 254 nm and the experiment was performed at room temperature. The size of the analytical colunm packed by C g was lS0X4.6mm (Spm) (Alltech, USA). The mobile phase of 0.75% TFA in water and acetonitrile were used in this experiment. The flow rates of the mobile phase were fixed at I ml/min. The constant volume of 0(d, was injected. This experiment was implemented at room temperature. The gradient mode was employed to isolate peptides. The complete gradient condition was listed in Table I. 

The 5x5 strip detector used in this work (Figure 1) was fabricated using a photomask technique to make the lithium and boron implants. Our laboratory data acquisition system consists of 10 spectroscopy channels, each with a 13-bit ADC, permitting strips to be analyzed individually. The ADCs are read out through a CAMAC crate with a Macintosh computer. Events are stored on disk in list-mode for subsequent processing. 

A feature of data acquisition that is becoming of greater interest in PET is that of list mode. In this, the events are not stored over preselected time frames in... 

Metabolite ID 1.4 operates in both interactive and batch mode. In the interactive mode, the user reviews the full-scan data prior to MS/MS generation. In batch mode, the user submits a list of samples to be analyzed and starts automated acquisition. With such automated approaches, the metabolic profile of a single compound can be evaluated in approximately 1.5 hours, provided that adequate separation can be achieved with short, narrow-bore columns and fast-gradient chromatography. 

Improvement with respect to these SRM methods was rendered possible by the availability of data-dependent acquisition or information-dependent acquisition (IDA), by which a tandem mass spectrometer can automatically switch from a survey mode to a dependent (or confirmation), full-spectrum MS/MS mode. In addition, the introduction of linear ion-trap-triple quadrupole (LIT-QqQ) hybrid instruments further extended the possibilities of LC-MS/MS in STA or GUS. In this instrument, the second mass analyzer can be used as either a conventional quadrupole mass analyzer or a linear ion trap, which by accumulation of ions provides enhanced full-spectrum sensitivity compared to a conventional quadrupole. The group of Weinmann used targeted SRM with up to 700 transitions as the survey detection mode, and the enhanced product ion (EPI) spectrum mode as the dependent mode (11). Whereas this procedure seems to be a more specific approach to STA as it allows searching rich spectra against those entered in libraries, the use of SRM as the survey mode cannot answer the more general clinical question as to whether an individual has been intoxicated at all, rather than intoxicated with a compound from a predefined list (12). Also, the use of only the positive-ion mode narrows the detection window. 

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