Metrology methods

The number of measurable layers of a stack is limited only by the optical contrast between the different layers. In practice stacks of ten layers and more can be analyzed by ellipsometry. Further advantages of ellipsometry compared with other metrological methods are the non-invasive and non-destructive character of the optical method, the low energy entry into the sample, the direct measurement of the dielectric function of materials, and the possibility of making the measurement in any kind of optical transparent environment. 

The Consultative Committee for Amount of Substance (CCQM) has set up a definition of primary methods [1, 2] and has selected some methods with the potential of being primary , from the viewpoint of the end user. From the point of view of metrology, methods used for linking the chemical measurements with the SI system at the highest level should not refer to other amount of substance standards. This requirement excludes methods which are relative in their principle. Some other methods identified as having the potential to be primary yield information expressed as amount fraction. This is essential for evaluation of purity, but in order to convert it to a value useful for transfer of the unit, additional information on the identity (molar mass) and content of the impurities is required. This additional information is needed to convert the result into amount content or similar quantities. 

Metrology methods for all of these requirements, one should also consider the means of verifying these requirements and tolerances. Metrology considerations are beyond the scope of this chapter, but dispensing equipment suppliers are often a good source of advice for metrology equipment for specific requirements. 

For a good overview of metrology methods for measurement of larger agglomerate particles in slurries see G. Vasilopoulos, Z. Lin, K. Adrian, Techniques for evaluating particles in CMP slurries Semiconductor Online (2000). See, http //www.semiconductoronline.com/doc/ techniques-for-evaluating-particles-in-cmp-sl-0001 (last accessed November 2014). 

Qualitative analysis methods should have well-grounded and generally adopted quantitative reliability estimations. At first the problem was formulated by N.P. Komar in 1955. Its actuality increased when test methods and identification software systems (ISS) entered the market. Metrological aspects evolution for qualitative analysis is possible only within the scope of the uncertainty theory. To estimate the result reliability while detecting a substance X it is necessary to calculate both constituents of uncertainty the probability of misidentifications and the probability of unrevealing for an actual X. There are two mutual complementary approaches to evaluate uncertainties in qualitative analysis, just as in quantitative analysis ... 

The well-known reaction of Ni(II) with dimethylglyoxime (H Dm) in alkaline medium under the influence of such oxidants as persulphate and iodine is widely used for the photometric determination of nickel. The red product (RP) of this reaction is used for this purpose. However, the nature of this red compound has not been defined yet. Using of peroxyacids makes it possible to obtain additional data concerning the conditions and mechanism of generation of RP as well as to improve the metrological pai ameters of the method. 

It is shown that metrological characteristics of the suggested methods are commensurable. Dissolved gas is pushed away by front of crystallization, takes the air and does not influence on the obtained results during the analysis of the water. Process is carried out at the lower temperature (-15°C), expelling chemical transformations of ingredients. The procedure was tested on different samples of natural and drinking water of the Kharkov region. 

The complex of the following destmctive and nondestmctive analytical methods was used for studying the composition of sponges inductively coupled plasma mass-spectrometry (ICP-MS), X-ray fluorescence (XRF), electron probe microanalysis (EPMA), and atomic absorption spectrometry (AAS). Techniques of sample preparation were developed for each method and their metrological characteristics were defined. Relative standard deviations for all the elements did not exceed 0.25 within detection limit. The accuracy of techniques elaborated was checked with the method of additions and control methods of analysis. 

The methodical elaboration is included for estimation of random and systematic errors by using of single factor dispersion analysis. For this aim the set of reference samples is used. X-ray analyses of reference samples are performed with followed calculation of mass parts of components and comparison of results with real chemical compositions. Metrological characteristics of x-ray fluorescence silicate analysis are established both for a-correction method and simplified fundamental parameter method. It is established, that systematic error of simplified FPM is less than a-correction method, if the correction of zero approximation for simplified FPM is used by preliminary established correlation between theoretical and experimental set data. 

The investigation leads to the elaboration of solid-phase spectrophotometric and test methods of different cationic surfactants determination in water. The detection limits of cationic surfactants with hydrocarbon radical length is 0.7 mg/dm, is 0.2 mg/dm, C is 0.009 mg/dm and is 0.003 mg/dm by using a 100 cm sample. Metrological performance of method was examined on the natural samples. Proposed method is highly sensitive, simple, rapid and guarantees ecological purity of analysis. 

The metrology characteristics of designed techniques of elements determination meet the requirements shown to test - methods of the analysis. The time of determination makes 15-20 minutes. 

A method is proposed of ionometric determination of the alkaloids of Papaver Somnifemm in the expert-criminal objects. This method is express, selective and characteristic of a high sensitivity (10 mole per liter) and good metrological chai acteristics. 

The analysis was performed by SRXRF at the XRF beam-line of VEPP-3, Institute of Nuclear Physics, Novosibirsk, Russia. For the accuracy control the different types of the International Certified Reference Materials were used. There were obtained all metrological characteristics, namely precision, accuracy and lower limits of detections. This is the SRXRF method, that allow to analyze the sample mass of 0.5 mg directly without the destruction. The puncture from patient may be picked out more than once. 

The simplest calibration procedure for a gas flow-measuring device is to connect it in series with a reference meter and allow the same flow to pass th tough both instruments. This requires a reference instrument of better metrological quality than the calibrated instrument. One fact to consider when applying this method is that the mass flow rate in the system containing both instruments is constant (assuming no leakage), but the volume flow rate is not. The volume flow rate depends on the fluid density and the density depends on the pressure and the temperature. The correct way to calibrate is to compare either the measured mass... 

It should be recognized that, in some cases, it is not difficult to set up a traceable measurement system. The best examples of this are in physical metrology where traceability is often based on direct measurements of the SI units. There is also general agreement that a similar SI fink is highly desirable in the case of chemical measurements, but, for a variety of reasons, direct chemical traceability is difficult to achieve in most of the analytical chemistry applications. Only a very few analytical chemistry procedures exhibit a direct measurement capability that allows the set-up of a traceable measurement pathway such as in physical metrology measurements most of these procedures have been accepted as primary methods if carried out under certain constraints (CCQM 1998). 

Halverson J. 1984. A review of application of mass spectrometry to low-level radionuclide metrology. Nucl Instrum Methods Phys Res 223 349-355. 

Primary methods have the highest metrological qualities, whose operation can be completely described and understood, and for which a complete uncertainty statement can be written down in terms of SI units. Such methods are used by national laboratories participating in the development of a national or international chemical measurement system. 

Associated with method validation, but not part of it, are two properties of results that have been previously mentioned. These parameters are measurement uncertainty and metrological traceability. Measurement uncertainty is covered in Chapter 6 and metrological traceability in Chapter 5. If considered at the planning stage of method validation, the information obtained during validation is a valuable input into measurement uncertainty evaluation. Traceability depends on the method s operating procedures and the materials being used. 

Section 5.2 introduced the subject of metrological traceability and calibration and the use of pure chemical substances and reference materials in achieving trace-ability. Reference materials are used as transfer standards. Transfer standards are used when it is not possible to have access to national or international standards or primary methods. Transfer standards carry measurement values and can be... 

If we try to refine the adequacy between the measurement procedures and the practical needs for wastewater quality monitoring, different metrological (analytical) characteristics have to be considered, such as detection limit, reliability and robustness (Table 3). Even if it is very difficult to compare the analytical methods carried out in the laboratory with on-site measurements (with on-line or tests kits), this presentation points out the main features of the measurement required for different needs. These characteristics define the quality of the available information [3], which constitutes one of the major problems that... 

Snow, especially its water-soluble fraction, is one of the most sensitive and informative indicators of mass-transfer in the chain air - soil - drinking water. Therefore analytical data on snow-melt samples were selected for inter-laboratory quality control. Inter-laboratory verification of analytical results estimated in all the groups have shown that relative standard errors for the concentrations of all the determined elements do not exceed (5-15)% in the concentration range 0.01 - 10000 microg/1, which is consistent with the metrological characteristics of the methods employed. All analytical data collected by different groups of analysts were tested for reliability and... 

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