Response Dynamic Range

The concentration-response relationship, unlike ion mobility spectroscopy detectors, is usually linear. For phosphorus, this relationship remains linear over a large concentration range. However, since sulfur exists in the flame as S2, the concentration-response relationship is a second-order one. Response linearity is related to the square root of sulfur concentration. The overall dynamic range for both sulfur and phosphorous are over 10 or even 10  

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The ECD is well suited as a selective detector for compounds with high electron affinity and limited linear response (dynamic range 104 with nitrogen). ECD detection is mainly used for analyses of chlorine-containing pesticides. Because of the presence of a radioactive source in this detector, it is subject to special regulations (e.g. inspections location and maintenance visits). 

Spatial distortion Count rate (cps) Absorption efficiency (Wavelength) Uniformity of response Dynamic range at one setting of gain (at multiple gain settings) Energy discrimination... 

After determining selectivity and sensitivity, dynamic range of the detection response is also a factor to be considered. Response dynamic range is the concentration range between the limit of quantification (LOQ) and the limit of linearity (LOL). The LOQ is the lowest concentration at which quantitative measurements can be made. The LOL represents the concentration level at which the calibration curve departs from linearity. LOD and LOQ are different in that the LOQ is usually somewhat higher than the LOD (Figure 5.1). Some contemporary detectors have... 

The response dynamic range of the typical SAW sensor is very broad and could be up to six orders of magnitude. The sensor reaches its saturation point only when the target chemical in the sample is sufficiently concentrated to occupy most or all active sorption sites available on the polymer-coated surface. 

Theoretically, any substances that can be ionized by the selected UV source can be detected. In the past, this detection technology was used to detect various organic substances., but it is also effective in detecting inorganic substances (e.g., H2S, NHj, etc.). PID is quite sensitive, as its Umit of detection reaches low parts-per-million levels and into parts-per-billion levels. Response dynamic range can be up to six orders of magnitude. 

In addition to controlling the bias, there are several constraints on the design of the front-end electronics the noise levels, frequency response, dynamic range, power dissipation, and size must be consistent with system-specific requirements. Even though most modern detectors include ESD protection circuitry, our front-end circuitry should not generate large transient voltages. 

In order to realise such a high dynamic range, either a local compensation coil at the location of the SQUID [9] or a gradiometric excitation coil like the double-D coil have to be used. In case of the electronic compensation, the excitation field and the response of the conducting sample is compensated by a phase shifted current in an additional coil situated close to the SQUID-sensor. Due to the small size of this compensation coil (in our case, the diameter of the coil is about 1 mm), the test object is not affected by it. 

The geometric compensation by means of a gradiometric coil is realised by placing the SQUID exactly between the two halfs of the coil, in order to detect only the response of the sample. In both cases we could achieve a reduction of the excitation field at the location of the SQUID of up to 1000. Electronic and geometric compensation together leads to an improvement of six orders of magnitude in the dynamic range, compared to a system without excitation field compensation. 

Cg pH-sensitive film had a dynamic range from 6 to 8 and Cg-film responded at higher pH values (8-10).The membranes showed good reproducibility, reversibility and a short response time (<10 s). They also can be used for at least 3 months without any considerable absolution deviations. These sensors can be used for direct determination of pH in drinking water detergent and dishwasher liquid that have good agreement with pH meter data. 

The dynamic range of LC detectors is usually considerably less than their GC counterparts which evinces more care in determining sample size in quantitative analysis. A GC detector may have a linear response over a concentration range of five or six orders of magnitude, for example, the flame ionization detector, whereas an LC detector is more likely to have a dynamic range of only three orders of magnitude and some detectors considerably less. 

When the linear range is exceeded, the introduction of more analyte continues to produce an increase in response but no longer is this directly proportional to the amount of analyte present. This is referred to as the dynamic range of the detector (see Figure 2.6). At the limit of the dynamic range, the detector is said to be saturated and the introduction of further analyte produces no further increase in response. 

It is important for obtaining precise results that the signals from the samples to be determined should lie on the linear part of the calibration graph as elsewhere within the dynamic range a small change in detector response corresponds to a relatively large range of concentrations. 

Figure 2.6 Detector response curve showing (a) ideal behaviour, (b) real behaviour, (c) its linear range, (d) its dynamic range, (e) the noise level, and (f) the limit of detection at three times the noise level.

Dynamic range (of a detector) The range over which the addition of further analyte brings about an increase, however small, in detector response. 

The region from A to D is called the dynamic range. The regions 2 and 4 constitute the most imfwrtant difference with the hard delimiter transfer function in perceptron networks. These regions rather than the near-linear region 3 are most important since they assure the non-linear response properties of the network. It may... 

NPD (FTD) Relatively high sensitivity Specific response Smaller dynamic range than FID Susceptible to operating conditions [31]... 

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