Measurement limitations

Fig. 6 Error of measuring limit length crack depth by using calibration curve for infinitely long crack.

Validation versus Rectification The goal of both rectification and validation is the detecI ion and identification of measurements that contain systematic error. Rectification is typically done simultaneously with reconciliation using the reconciliation resiilts to identify measurements that potentially contain systematic error. Vahdation typically rehes only on other measurements and operating information. Consequently, vahdation is preferred when measurements and their supporting information are hmited. Further, prior screening of measurements limits the possibihty that the systematic errors will go undetected in the rectification step and subsequently be incorporated into any conclusions drawn during the interpretation step. 

Sensitivity is a measure of the smallest concentration that can be either measured [limit of detection (LOD)] or accurately quantitated [limit of quantitation (LOQ)]. In the USA, the method for measuring LOD or LOQ is left up to the method developer. European requirements for determining LOD and LOQ are very specific the LOD is based on the mean plus three standard deviations for 20 control blank samples, and the LOQ is defined as the lowest concentration giving an acceptable CV. 

Earlier, Venczel, Ibl, and co-workers (V3,18) measured limiting currents in the reduction of ferric and ceric ions at a vertically oriented cathode where... 

The main goal of the Planck instrument is to improve the accuracy of the measurement of the cosmic microwave background (CMB), in order to extract cosmological parameters that remain poorly constrained after the results of WMAP (Wilkinson microwave anisotropy probe) and of the best ground-based experiments. The basic idea of HFI-Planck is to use all the information contained in the CMB radiation, i.e. to perform a radiometric measurement limited by the quantum fluctuations of the CMB radiation itself. In these conditions, the accuracy is only limited by the number of detectors and by the duration of the observation. 

The solution-processed doped silicon films described above (baked at 500 °C for 2 hr) exhibited high electrical resistivity (greater than 300 Qcm), which is the measurement limit of the instrument we used. To lower the resistivity, we tried an additional rapid thermal annealing (RTA) of the film prepared from the copolymerized solution with 1 wt% phosphorus concentration. In this RTA, the SiC plate on which the sample was placed was irradiated with infrared (IR) light from a 1-kW IR lamp. The RTA conditions were 600 °C for 2 hr, 650 °C for 20 min, 700 °C for 5 min, and 750 °C for 5 min these temperatures were that of the SiC plate, and the temperature of the Si film is estimated to be several dozens of degrees lower than that. 

Taking Tinto account implies the ability to operate the reactor at a particular T, and hence to measure and control T. A thermostat is a device in which T is controlled within specified and measurable limits an example is a constant-T water bath. 

Part B information to be defined by the FSA customer once the contract has been awarded to a contractor, e.g. the sample storage conditions to be used, the methods to be used, the IQC procedures to be used, the required measurement limits (e.g. limit of detection (LOD), limit of determination/ quantification (LOQ), and the reporting limits)... 

The measurement limits (i.e. limit of detection (LOD) limit of determination/quantification (LOQ), and reporting limits, etc.). 

Measurements of the chemical composition of an aqueous solution phase are interpreted commonly to provide experimental evidence for either adsorption or surface precipitation mechanisms in sorption processes. The conceptual aspects of these measurements vis-a-vis their usefulness in distinguishing adsorption from precipitation phenomena are reviewed critically. It is concluded that the inherently macroscopic, indirect nature of the data produced by such measurements limit their applicability to determine sorption mechanisms in a fundamental way. Surface spectroscopy (optical or magnetic resonance), although not a fully developed experimental technique for aqueous colloidal systems, appears to offer the best hope for a truly molecular-level probe of the interfacial region that can discriminate among the structures that arise there from diverse chemical conditions. 

Implementation of microanalytical devices presents some issues mostly related to the scale of the volumes. In fact, successive reduction in the sample volume may compromise analysis either because the measurement limit of the analytical method is exceeded or because the sample is no longer representative of the bulk specimen. Another drawback for microchip devices is microvolume evaporation of both sample and reagent from the microchip, compromising quantitative determination or inducing unwanted hydrodynamic flows. This problem has been addressed by designing pipetting systems that automatically replace fluid lost by evaporation or by enclosing the chip in a controlled... 

The temperature of the screw was measured by several investigators [29-32]. The measurements were performed by mounting thermocouples in an axial hole bored in the center of the screw or by protruding the thermocouples into the melt flow. The sensor signals were then transmitted to a chart recorder using an electrical rotary union. The technology available at the time of these measurements limited the number of sensors in the screw and the quality of the data. 

NCRP (1993). National Council on Radiation Protection and Measurements. Limitation of Exposure to Ionizing Radiation, NCRP Report No. 116 (National Council on Radiation Protection and Measurements, Bethesda, Maryland). 

The spiked filters were placed in a 50-mL beaker with the spiked side up and 1 mL of water was added. The beaker was shaken so that all of the filter area had been washed by the water. One mL of the reduction-buffer solution without the sodium hydrosulfite was added to the filter and water. The beaker was shaken a second time. The filter was then turned over (spiked side down) and the beaker placed in an ultrasonic bath for 15 minutes. At the end of this period, the solution in the beaker was colored. A 1-mL aliquot of this solution was transferred to a 4-mL vial. One mL of a freshly prepared solution of 100-mg sodium hydrosulfite in 10-mL phosphate reduction buffer was then added to the vial. The vial was then capped and shaken several times during the course of an hour. During this time, the original color of the solution disappeared or changed to a different color, depending on the dye present. This solution was then injected into the liquid chromatograph. A 10-yL aliquot was used, giving a measurement limit of 0.38 ng benzidine/yL. The analytical reproducibility at this limit was 10% coefficient of variation (CV). 

The relationship between the measured limiting specific viscosity [17] and the molecular weight (A/ ) is as follows ... 

Klein, K. (2004) Permittivity measurements of high conductivity specimens using an open-ended coaxial probe-measurement limitations, Journal of Environmental Engineering Geophysics 9, 191-200... 

Operators understand the behaviour of the instrument if measurement limits are exceeded. 

The weaknesses associated with the flow through an orifice and angle of repose measurements limit their application for powder flow studies and hopper designs. Consequently, several powder shear testers and methods that permit a more thorough and precisely defined assessment of powder flow characteristics were developed. Shear testers that measure the frictional characteristics of a powder bed under load yield valuable information with regard to powder flow in high-speed tablet equipment. A number of types of shear cell testers are available, but the most common types used in the pharmaceutical industry are the Jenike shear cell and the Schulze ring shear tester.61,62... 

Synovec and Yeung developed a highly selective and sensitive laser-based CD detector for both conventional and microbore liquid chromatography [30] and applied it to the analysis of complex mixtures of optically active metal complexes. As expected limits of detection are very low. For example for the determination of (+) trisfethylenenediamine) cobalt (HI) using an Ar-ion laser source, a microbore column, and a CD detector operating at 488 nm, the measured limit of detection is 5.6 ng. 

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