Data acquisition rate, enhanced

As with aU Q-based instruments, it is also possible to increase the time that each of Qi and Q3 is set to transmit the precursor/product ion pairs (so-called dwell times) while still maintaining data acquisition rates that can provide the requisite number of data points across the peak. Longer dwell times result in detection of larger numbers of ions (at trace anal5he levels the detected ion beams are of very low intensity so the arrival of discrete ions at the detector is statistically distributed in time, see discussion of ion beam shot noise in Chapter 7), and thus enhanced sensitivity. In addition, once dwell times are set, SRM dwell times for a QqQ are eonstant across the time frame of a chromatographic peak. These constant dwell times are a distinguishing feature of QqQs (and Qs) relative to quadrupole ion traps (see below). 

Other properties that define instrument capahihty include sensitivity, hmits of particle size resolution, and rate of data acquisition. For example, detection limits for green fluorescence range from 600 molecules of equivalent soluble fluorochrome (MESF)/cell to <50 MESF/cell, and particle sizes of 0.5 pm to 50 pm may be resolved in some instruments. Acquisition rates in analytical instruments vary from <3,500 cells (events)/s in older instruments, to 10,000 events/s in the newest models. High acquisition rates and the availability of automatic samphng devices for microplate-based assays have enhanced the efficiency of analyzing large sample sets. 

FX2 (C67C68013), which integrates the USB 2.0 transceiver, serial interface engine (SIE), enhanced 8051 microcontroller, and a programmable peripheral interface into a single chip. This is a very cost-effective solution that shortens development time and provides a small foot print for use in a mobile platform. Although not important in this application, the FX2 can be operated at the maximum USB 2.0 data rate of 45 Mbytes/s. The 8051 microcontroller nms software that can be downloaded to an internal RAM via the USB or from an EPROM (Atmel 240164). Additionally, the 8051 microcontroller has three high speed coimter/timers, which provide data acquisition and control of various components as discussed below. 

The PLC and microprocessor controls have enhanced the flexibility and versatility of the hydraulic press. Virtually any function on the press can be programmable if so wanted. Force and velocity rates can not only vary but also be displayed as a function of time or position to provide results that previously were not economically possible. Presses and press systems can be interfaced with management information systems for production reporting, data acquisition, statistical process control, or predictive maintenance purposes. In addition to being easy to use, these controls are truly beneficial. 

The bi-phasic contrast-enhanced scan during the arterial-dominant (15-25 s post injection) and the portal-venous (50-70 s post injection) perfusion phase after bolus-like contrast administration is widely accepted as standard for the optimised display of the complex vascularization of the liver and potential hepatic lesions. Thin-slice data acquisition by modern multi-slice scanners allows isotropic multiplanar reformations with equivalent representations as known from MR. Moreover, CT-arterioportography, also in comparison to modern MR, became less important not least due to the relatively high rate of false positive findings (Vogl et al. 2003). 

An important issue regarding selectivity concerns the assessment and quantitation of the matrix effects. Because UHPLC yields peaks with bases as narrow as 1 s, an overall enhancement of the chromatographic resolution is obtained. The potential co-elution and ion suppression are thus reduced, which enhances the sensitivity and reliability of the MS. However, while UHPLC improves the separation throughput and resolution, practical issues with using MS may arise because acquiring sufficient data points (>15 points per peak) is essential to ensure reliable quantitation. As previously mentioned (Section 4.2.2), instruments with high acquisition rates and low dwell times are, therefore, preferentially selected for quantitative determination. 

Figure 2, Partial 100-MHz 1H NMR spectra of methyl fi-D-glucopyranoside, showing a two-pulse nonselective inversion-recovery determination of the spin-lattice relaxation rates. AU spectra were monitored as follows pulse width (90°) — 67 ftsec number of transients — 8, pulse delay = JO sec, acquisition time = 4 sec, data points = 4096, spectral width — 500 Hz, and sensitivity enhancement — 1.5 sec. The time interval (sec) between the 180°- and 190°-pulses are indicated to the right of the respective spectra.

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