Integrators sampling rate

The signal was recorded on a Hewlett Packard Integrator Model 3393A Integrator. Samples were injected onto a 30 m megabore column coated with 1.5 micron DB-5 purchased from J W Scientific. The flow of nitrogen carrier gas was maintained at 30 cc/min. The column was equilibrated at 150°C. On injection of the sample, this temperature was maintained for five minutes followed by a programmed increase at a rate of 8°C/min. to a maximum of 300°C, which was maintained for 30 minutes. 

The detectors used with UPLC systems have to be able to handle very fast scanning methods because peak half-height widths of around 1 s are typically obtained with columns packed with 1.7-p.m particles. In order to accurately and reproducibly integrate an analyte peak, the detector sampling rate must be high enough to capture enough data points across the peak. Conceptually, the sensitivity increase for UPLC... 

Figure 3.4 Energy decay relief for occupied Boston Symphony Hall. The impulse response was measured at 25 kHz sampling rate using a balloon burst source on stage and a dummy-head microphone in the 14th row. The Schroeder integrals are shown in third octave bands with 40 msec time resolution. At higher frequencies there is a substantial early sound component, and the reverberation decays faster. The frequency response envelope at time 0 contains the non-uniform frequency response of the balloon burst and the dummy-head microphone. The late spectral shape is a consequence of integrating measurement noise. The SNR of this measurement is rather poor, particularly at low frequencies, but the reverberation time can be calculated accurately by linear regression over a portion of the decay which is exponential (linear in dB).

The shortest integration time of the counter is currently set to 1 jls, corresponding to a maximum sampling rate of 1 MHz. The actual time resolution is limited by the high voltage driver of the Pockels cell with approximately 20 jis switching time. 

The signal quality (= low detector noise) and sample rate should be sufficiently high to obtain correct results, otherwise post processing of the data is necessary, such as smoothing, baseline correction, etc. Even then the result of the integration in Eq. 6.126 depends very much on the extension of the baseline, and the obtained value of the second moment can be very inaccurate (Chapter 2.7, Section 6.5.3.3). 

When dynamic methods are applied, the measured profiles should include enough points and sufficiently low detector noise to perform numerical calculations (e.g. integration). This is discussed in another context in Section 6.5.3.2 and Chapter 2.7. The number of data points in the measured profile can be increased by changing the flow rate of the pump or the sample rate. 

These criteria were met with the exception of criteria 3. Jacob et al.(65) found that the scale model version of the RAC had a particle size cut of 20 ym rather than the desired 1-10 ym cut.(See Figure 17) The RAC performs well in preserving the chemical integrity of the collected droplets and provides a high sampling rate however, it has the drawback that it does not collect efficiently the smaller... 

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