Detector properties

Column and detector properties determine the minimum amount of a component that can be reliably distinguished from the background noise. If we arbitrarily select a signal to noise ratio of 4 as the minimum value for the confident determination of a peak in a chromatogram then for a mass sensitive detector the minimum detectable amount is given by... 

Table 4.10 Bulk graphic detectors property and solute property chromato- ...

What is the molecular underpinning for the coincidence-detector property of the NMDA receptor The NMDA receptor is a channel protein that sits in the postsynaptic membrane (Fig. 53-3). The electrical stimulation of a presynaptic cell releases glutamate which binds to the postsynaptic AMPA and NMDA receptors. Glutamate binding to the NMDA receptor alone is not sufficient to activate... 

At the outset, one must understand certain principles of GC to assess if it is a proper analytical tool for the purpose. If so, how to achieve the best separation and identification of component mixtures in the sample with reasonable precision, accuracy, and speed And what kind of detector and column should be selected for the purpose It is, therefore, important to examine the type of compounds that are to be analyzed and certain physical and chemical properties of these compounds. Information regarding the structure and the functional groups, elemental composition, the polarity in the molecule, its molecular weight, boiling point, and thermal stability are very helpful for achieving the best analysis. After we know these properties, it is very simple to perform the GC analysis of component mixtures. To achieve this, just use an appropriate column and a proper detector. Properties of columns and detectors are highlighted below in the following sections. 

The simple detector properties such as geometry and sensor cell dimensions are given in length (cm), time (sec) or mass (g) and there is no disagreement in the literature regarding such specifications. The... 

The list below defines most of the detector properties important to Raman applications, particularly for dispersive spectrometers. Specifications of particular devices will be discussed in subsequent sections. More specific definitions are provided for CCD detectors in Section 8.5.2. 

In chromatography, a series of signals from the detector output is registered as the chromatogram. The qualitative information is derived from the retention time, tms, which is determined by the chromatographic process and which depends on the thermodynamic properties of both the stationary phase and the solutes. The quantitative information stems from the area under the signal, and is determined by the measurement process and depends on the detector properties. In so doing, it is assumed that the sample component elutes quantitatively from the analytical column. 

Diastereomers may have differing detector properties. For quantitative analysis it is necessary to determine the calibration curve. 

In the case of the detection limit we have to distinguish between the minimum detectable concentration and the minimum detectable mass. The minimum detectable concentration of a solute in the sample solution depends only on the detector properties and on the optical properties of the solute, i.e. its absorbance, if the maximum tolerable sample volume with respect to the retention volume of this solute is injected. The minimum detectable concentration is independent if the column dimensions, plate number or capacity factor. 

Detector properties These have to be characterised as follows ... 

The detectors are divided into four classes based on the general detection principle or detector selectivity. A short description of the working principle and the application range is given for each detector. Detector properties such as detection limits, selectivity, and dynamic range are summarized in tables. 

Currently, several hundred reagents are available for the preparation of diastereomer derivatives, and this list continues to grow. In consequence, any type of comprehensive coverage is impossible here. As well as the nature of the reactive group, cost, reactivity, stability, and availability are important selection criteria, since in advance of trial experiments, success cannot be guaranteed for analytes not studied previously. For trace analysis, the choice of a more selective and sensitive detector for the analysis may minimize the number of options to reagents with suitable characteristic detector properties. 

Blue-gray crystals with a metallic luster, insoluble in water d o 7.5. Crystal structure C 7 type. Exhibits catalytic and radio-detector properties. 

Quantitative application of Raman spectroscopy generally requires pretreatment to reduce background variance and often also includes the application of chemometric methods. The success of both steps depends on a high level of both abscissa and ordinate stability and linearity. Scattering intensity and the relative intensities of Raman lines within a spectrum depend on a variety of measurement conditions laser power, laser wavelength, spectral resolution, detector properties, and arrangement of the excitation and collection optics. 

Averages of detector properties over 100 pixels near the center of the array are shown in Table I. riG increases rapidly with Vj, and t/G A at all Ffr for A < 25. The same rjG vs. A was found in sin e-pixel devices from the same wafer, with riG roughly constant for 25 < A < 40/on, so it is likely that the full array is sensitive to 40 paa (see T. Herter, these Proceedings). There are 276 bad pixels, or less than 2% of the array. 

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