Sensitivity and dynamic range

It is most important to agree on the definition of assay sensitivify. Operationally this sensitivity is usually taken at the lower limit of defection (LED 

It is therefore essential that the variability of an assay be known precisely (Ezan and Grassi, 2000). The performance of an assay in terms of accuracy, reproducibility (CV, interassay variation), and repeatability (CV, intraassay variation) should be determined. For an ELISA, accuracy in the range of 85 to 115% of the standard value and CVs in the range of 15 to 20% are common. The assay limit of quantification is then taken as the lowest concentration of analyte that provides CVs under, e.g., 10% and accuracy within, e.g., 15% of the standard value. A discussion of factors leading to imprecision of microarrays will be addressed later. 

Analyte LLD (pg/mL) LLD (pM) Signal Detection Microarray support Reference 

TSH 2 -0.1 Texas Red, EITG Gonfocal microscope Plastic Ekins 

IL-4 2 0.14 HRP colorimetric Microplate reader 96-well plastic Pierce Endogen 

Because the amount of polymer samples available is usually not limited, it is possible to underestimate the sensitivity issue in MALDI polymer characterization. In reality, the use of a MS instrument that provides high sensitivity and a wide dynamic range of ion detection is pivotal to the success of polymer analysis. This is true not only for the measurement of polymer average mass, but also for the determination of polymer composition [110, 113-121]. With limited detection 

These values were significantly different from those obtained by the more sensitive method (99% confidence limit from t-test). In addition, the precision of the method using the less-sensitive method was also downgraded. 

The upper mass range of a polymer that can be analyzed by MALDl-MS is dependent on the polymer type. For example, Danis et al. reported the detection of water-soluble poly(styrenesulfonic acid) with a molecular mass just below 400000 [122], and the detection of a poly(methyl methacrylate) sample with a molecular mass of about 256000 [17]. Multiply charged ions from a starburst polyamidoamine dendrimer with a molecular mass as high as 1.2 milbon has been reported by Savickas [123]. Yalcin et al. showed that polybutadienes of narrow polydispersity with masses up to 300000 Da, and polyisoprenes of narrow polydispersity with masses up to 150 000 Da, can also be analyzed [42]. 

Because it is necessary to reduce the molar amount of polymer loading as the molecular mass increases, this would suggest a practical hmit to the mass range for polymer analysis by MALDI. As molecular mass increases, the sensitivity of the instrument is challenged on two fronts (i) decreased sensitivity due to a loss in detector efficiency and (ii) decreased sensitivity from the requirement of lower (molar) sample loading. In the analysis of PS, this hmit appears to occur at -1.5 milHon Da. In order to obtain the MALDI mass spectrum of PS with a nominal mass of 1.5 miUion Da [29], 5 fmol of total polymer was loaded onto the probe. 

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When compared to fluorescent proteins, fluorophores and quenchers of fluorescence (short quenchers) are small molecules with sizes varying from 1 to 10 A. They are the main building blocks for constructing small molecule FRET probes. As molecular entities, they might influence the performance of the probe to a great extent. Their fluorescent properties will determine the sensitivity and dynamic range of the sensor. The success of the probe for a specific application will depend on the selection of the right fluorophores... 

Many chemically-synthesized GaN samples exhibit a peak from the dominant WZ form, and a much smaller peak from the ZB form. Because of the good resolution, sensitivity, and dynamic range of 71Ga MAS-NMR, polymorphs present at levels below the detection sensitivity of XRPD of 1% could be identified. Quantitation needs to take into account the differing nutation behavior (mentioned in Sect. 3.2.1 in terms of effective 90° pulse lengths) of the ZB and WZ 71Ga peaks. 

Yost, R.A., McClennan, W. and Menzzelaar, H.L.C. Enhanced full scan sensitivity and dynamic range in Finnigan MAT ion trap detector with automatic gain control of software. Finnigan MAT IDT 22. 

Detection sensitivity and dynamic range where to obtain content and at what cost ... 

Although DC maturation can be used to detect sensitizing capacity, major concerns remain on this assay (i) the limited reproducibility within and between laboratories due to inter-donor variability and variations in cell isolation and culture techniques (ii) the lack of sensitivity and dynamic range [122]. To circumvent interdonor variability cell lines such as THP-1, U937, KG-1 and MUTZ-3 have been used. 

One major aspect of quantitative analysis is sensitivity and dynamic range of linearity. Such data have been reviewed (2) for the gas density, thermal conductivity, and flame ionization detectors. Since response is a function of molecular weight in the gas density detector, it is difficult to make comparisons in a simple manner. In general, however, the sensitivity of the gas density cell is about twice that of comparable thermal conductivity cells and about one-tenth that of flame ionization detectors (when bleed of the column is limiting). 

Problem 10 Loss of detector sensitivity and dynamic range. 

The use of optical methods to study the dynamics and structure of complex polymeric and colloidal liquids subject to external fields has a long history. The choice of an optical technique is normally motivated by the microstructural information it provides, its sensitivity, and dynamic range. A successful application of an optical measurement, however, will depend on many factors. First, the type of interaction of light with matter must be correctly chosen so that the desired microstructural information of a sample can be extracted. Once selected, the arrangement of optical elements required to perform the required measurement must be designed. This involves not only the selection of the elements themselves, but also their alignment. Finally, a proper interpretation of the observables will depend on one s ability to connect the measurement to the sample s microstructure. 

A simple calculation demonstrates the tremendous power of electrochemical reaction rate measurements due to their sensitivity and dynamic range. Dissolution current densities of 10 nA/cm2 are not tremendously difficult to measure. 

The newly available Odyssey and Aerius infrared imaging systems make it possible to probe whole cells with two-color infrared fluorescently labeled antibodies (anti-phosphopeptide, for example) that are used to detect changes in intracellular kinase signaling (Chen et al., 2005). The advantage of using infrared-labeled probes lies in the increased sensitivity and dynamic range and consequent reduction in the use of reagents. 

Detector response can be defined in two ways. It can be taken as the voltage output for unit change in solute concentration in which case in a similar way to detector sensitivity and dynamic range, the solute used for measurement must to be specified. Alternatively, it can be taken as the voltage output that would result from unit change in the physical property that the detector measures, e.g. refractive index or carbon content. In the latter case the dimensions of the response will vary with the nature of the property being measured. 

A significant disadvantage of NMR-based approaches for the characterization of natural product mixtures is represented by the much lower sensitivity and dynamic range of NMR spectra compared to MS. Furthermore, the often high complexity of 2D NMR spectra obtained for mixtures can make their interpretation challenging. 

The accuracy to which a mass spectrometer can determine the molecular weight of an ion is, like sensitivity and dynamic range, a common performance bench-... 

Column diameter can be adjusted to meet the sensitivity and dynamic range needs of the quantitative method. Decreasing the bore size from 3.0 to 2.1 while decreasing the flow rate may also show a concentration effect on band width and thus peak area response [43]. As shown in the equation below, if the diameter of the column is decreased from 3.0 to 2.1, the peak area response should double as follows ... 

The fluorescent ddA 5 -triphosphate derivative (163) was shown to be an effective substrate for terminal transferase, and various DNA polymerases. The resultant DNA could then be detected by fluorescence spectroscopy. A molecular beacon DNA probe incorporating a donor and a quencher dye has been reported, " which shows high sensitivity and dynamic range. Such molecular beacons are anticipated to have use in DNA/RNA and pro-tein/DNA/RNA interactions. 

It became clear in the study that the twisted stmcture is the key to the coupling mechanism. The interesting aspect of this investigation is that the response appears to be directly proportional to the geometrical stmcture and the absorbency of the solution. The role of the absorbency is clear and the twist stmcture enhances the sensitivity and dynamic range. 

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