High sampling rate

Acquisition times commonly vary from seconds to minutes, often with negligible time between acquisitions, even when measuring multiple locations simultaneously (multiplexing). The dedication of different areas on the charge coupled device (CCD) detector to each measurement point makes this possible. The detectors used for MIR and NIR instruments cannot be multiplexed in the same fashion and must measure multiple samples sequentially. 

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Injector The sample, typically 5-200 )J,L, is placed in the carrier stream by injection. Although syringe injections through a rubber septum are used, a more common means of injection is the rotary, or loop, injector used in ITPLC and shown in Figure 12.28 of Chapter 12. This type of injector provides reproducible injection volumes and is easily adaptable to automation, a feature that is particularly important when high sampling rates are desired. 

Finally, FIA is an attractive technique with respect to demands on time, cost, and equipment. When employed for automated analyses, FIA provides for very high sampling rates. Most analyses can be operated with sampling rates of 20-120 samples/h, but rates as high as 1700 samples/h have been realized. Because the volume of the flow injection manifold is small, typically less than 2 mb, consumption of reagents is substantially less than with conventional methods. This can lead to a significant decrease in the cost per analysis. Flow injection analysis requires additional equipment, beyond that used for similar conventional methods of analysis, which adds to the expense of the analysis. On the other hand, flow injection analyzers can be assembled from equipment already available in many laboratories. 

Because SPMDs have high sampling rates (Rs s) for vapor phase contaminants, all SPMDs are assembled in an environmentally controlled room equipped with an activated carbon air filtration system for the removal of airborne contaminants. SPMDs of almost any length can be prepared after allowance of space for the molecular welds or heat seals (i.e., 2.5 cm for each end). However, different... 

With recorded instrument waveforms, it is not practical to store as many as 256 samples per period for most waveforms, as done in sine wave table lookup oscillators. This would correspond to a very high sampling rate. At 44100 Hz sampling rate, waveforms two octaves above A-440 have about 50 samples per period. To maintain 256 samples per period would require a sampling rate of over 200 kHz, which is impractical due to the expense of the memory required. 

The use of ICP-MS provides some important benefits when coupled to an HPLC that separates As species prior to measurement. ICP-MS has fit-for-purpose limits of detection (LoDs) thus, analytical, not preparative, separation systems can be used with a high sampling rate ( 1 ms) in order to measure transient signals and to separately quantify closely eluting compounds from HPLC. HPLC-ICP-MS coupling can be achieved simply via a 50 cm piece of PEEK tubing without loss of peak resolution, whereas chromatographic flow rates are compatible with conventional ICP-MS spray chambers. 

Testing was not conducted to insure that each system configured could handle high sampling rates. Validation of the system did not include critical system tests such as volume, stress, performance, boundary, and compatibility. [FDA Warning Letter, 2000]... 

FIA is readily adaptable to the determination of dissolved nutrients in seawater. Methods for the determination of nitrate 11, 12), phosphate (13), and silicate (14) in seawater have been developed. We have used FIA methods at sea and they have proven to be quite reliable. Because high sampling rates are possible with FIA (i5), it is well-suited for oceanographic investigations of small-scale and mesoscale features in the ocean. It is particularly well-suited to applications where it is interfaced with the effluent of a submersible pumping system. 

Experimental data were obtained with on-line detector set-ups. Figure 6.27 shows the good consistency of the on-line and off-line analysis (= multiple fractions and HPLC analysis) for the injection of the EMD53986 racemic mixture. In this case a two-detector set-up of polarimeter and UV detector was used, which permits the solute-specific detection of both components (Epping, 2005, Jupke, 2004 and Man-nschreck, 1992). As the collection and analysis of multiple fractions with a high sample rate is tedious, the on-line measurement method should be used whenever possible. 

The relative standard deviations for sets of 15 repetitive measurements were 1.5% and 0.4% at concentrations of 1 and 10 pg/ml, respectively. The results obtained from this system correlated well with those obtained from the chromotropic acid. The simplicity, versatility, good precision, high sampling rate, and relatively low cost of the system make it attractive for the analysis of large numbers of formaldehyde samples. 

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... 

A corollary of the short sample residence time in the analytical path is the short wash time. Intermingling of successive samples, leading to pronounced carryover effects, is only a minor issue, and the next sample can be introduced without a long delay. This permits high sampling rates, typically 30—300 h-1, which can be exploited for, e.g., repetitive measurements, simultaneous determinations, titrations, standard additions and industrial quality control. 

A mono-segmented flow system (see 5.5.1) provides good conditions for organic/aqueous phase interaction the extraction process is carried out between two air bubbles and vortices are established inside the plug. An efficient extraction, with reduced sample dispersion, low carryover and thus a high sampling rate, is achieved, as demonstrated in the spectrophotometric determination of cadmium [195]. 

This innovation has been referred to a triangle programmed titration. However, a previous calibration step involving standard solutions was required to attain the analytical curve, a step that is not necessary in conventional titrations. Consequently, this innovation does not comply with the IUPAC definition of a titration, and can be regarded as a pseudotitration. The flow analyser is simple, robust and performs titrations at a very high sampling rate. 

As we saw earlier, the key point of GCxGC is the interface between the two columns, the modulator. This device ensures high sampling rates and the transfer of the sample from to while respecting Giddings s conservation rules. To guarantee conservation of the first-dimension separation achieved, the fraction eluted from the modulator should be no wider than about one-quarter of the peak width [13]. Recommended is the ensurance of at least three to four cuts per peak of the first dimension by the modulator. Thus, a Pm of 2-8 s is generally chosen. 

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