Synthetic calibration sample

A measured value is complete only when it is accompanied by a statement of its uncertainty and is required in order to decide whether or not the result is adequate for its intended purpose. The uncertainty value must be suitably small to show that the reported results can be accepted with confidence and to ascertain whether or not it is consistent with similar results. There is an uncertainty in the concentration of the calibration samples used both in synthetic calibration samples and calibrations of standard addition. Weighing and volumes, which are a must in most analytical methods, must include weighing errors volumes must include volume errors to take into account uncertainties associated with these steps of the analysis. These and others must also be included in the overall calculation of the analytical error. 

Normally, there is also an uncertainty in the concentrations of the calibration samples used both in the case of calibration with synthetic calibration samples as well as in calibration by standard additions. In both cases these errors can also be included in the calculation of the analytical error [34]. 

When calibrating with one synthetic calibration sample (cs) giving a signal Ys, the concentration of the unknown sample Cx can be calculated as ... 

The measured SAXS curve of the calibration sample must have been pre-processed in the usual way (cf. Sects. 7.3 - 7.6). Therefore it is important to have calibration samples with a well-defined thickness27. Because synchrotron beamlines can be adjusted to a fairly wide range of radiation power, it is important to have thin calibration samples for a high-power adjustment (e.g., common SAXS with wide slit openings) and thick calibration samples for low-power adjustments (e.g., USAXS with microbeam). For calibration samples from synthetic polymers, thicknesses ranging between 0.2 mm and 3 mm are reasonable. It appears worth to be noted that not only polymers, but as well glassy carbon [88] can be used as a solid secondary standard for the calibration to absolute intensity. 

Design of experiments (DOE) tools are widely considered to be some of the most important tools in the development of calibration models for PAT [22]. In cases where snfflciently relevant calibration samples can be synthetically prepared, DOE can be nsed to specify an efficient and effective set of calibration mixture standards for calibration development. Even in those PAT problems where synthetic standards cannot be prepared, the concepts behind DOE are nseful for understanding the importance of covering the needed composition and instrnment response space for a given problem. 

In 1987, Chasseur assayed cimetidine granules. This was the first reported use of a synthetically produced extended range for calibration calibration samples were produced with a range of content from 70 to 130% of label. In 1987, Osbomet used NIR to assay for nicotinamide in vitamin premixes. 

The amorphous material induces a broad hump or halo, in to the diffraction pattern. The width and the position of the halo indicate the distribution of interatomic distances in the structure of the material. The area under halo depends on the content of amorphous material, and therefore it is possible to semiquantitatively determine the content of amorphous material from the x-ray diffraction pattern, Mixtures of synthetic ash and common glass were used as calibration samples. 

Calibration can be achieved by the use of synthetically prepared cement minerals, although these may be difficult to obtain. Since the composition of the sample is variable, and therefore so is its mass absorption coefficient, it is advisable to introduce an internal standard to both the calibration samples and samples for analysis. The elimination of the effect of variable absorption is achieved simply by taking all measured lines as a proportion of a line from the internal standard. 

The abundance of LEU products is determined with a total uncertainty of 0.13% (Is) by measuring the 186 keV gamma rays with a Nal or GeLi well detector on 5 ml solutions containing a well-known amount of uranium, close to 0.5 g. The volume of the sample and synthetic calibration test solutions, their acid and U concentrations are kept in a very narrow range so that the self-absorption and coimting geometry be constant factors or minor variations be accurately... 

Gases for Calibration—Pure or research grade hydrogen, oxygen, nitrogen, and carbon monoxide will be needed to prepare synthetic standard samples as described in Test Method D 2505. (Warning—See Notes 4 and 5.) Certified calibration blends are commercially available from numerous sources and can be used as the synthetic standard samples. 

Prepare at least three synthetic standard samples containing the compounds to be determined over the range of concentration desired in the products to be analyzed, using the pure gases or the certified blend. For the preparation of the second, third, and following calibration samples it... 

The definitive document for this technique is ISO 12677 2003, which appeared in 2003. The essence of the technique is the conversion of the ignited sample into a glass bead or button by fusing in a suitable lithium borate-based flux. Once treated in this way, all particle size and mineralogical effects that will lead to inaccuracies are destroyed. Hence, synthetic calibrations can be set up in a similar manner using synthetic mixtures of pure oxides or carbonates. 

Analysis of Standards The analysis of a standard containing a known concentration of analyte also can be used to monitor a system s state of statistical control. Ideally, a standard reference material (SRM) should be used, provided that the matrix of the SRM is similar to that of the samples being analyzed. A variety of appropriate SRMs are available from the National Institute of Standards and Technology (NIST). If a suitable SRM is not available, then an independently prepared synthetic sample can be used if it is prepared from reagents of known purity. At a minimum, a standardization of the method is verified by periodically analyzing one of the calibration standards. In all cases, the analyte s experimentally determined concentration in the standard must fall within predetermined limits if the system is to be considered under statistical control. 

The composition of steels or other metals is commonly analyzed by emission or X-ray spectrometry during and after the production process. Both methods have to be calibrated by solid samples. These are either exactly analyzed samples taken from the same process or synthetic melted mixtures of the matrix with added accompanying elements (RMs). Available CRMs are then used to control the slope of the calibration function. Today, available RMs and CRMs are increasingly and exclusively used in spectral laboratories as the chemical analysis became much restricted and typical control laboratories were totally closed (Slickers 1993). 

Rossbach M, Ostapczuk P, Emons H (1998) Microhomogeneity of candidate reference materials Comparison of solid sampling Zeeman-AAS with INAA. Fresenius J Anal Chem 360 380-383. Rossbach M, Stoeppler M (1987) Use of CRMs as mutual calibration materials and control of synthetic multielement standards as used in INAA. J Radioanal Nud Chem Artides 113 217-223. Sargent M (1995) Development and application of a protocol for quality assurance of trace analysis. Anal Proc 32 71-76. 

The observations were performed at ESO using the 1.52m telescope and FEROS. The obtained spectra have high nominal resolving power (R 48000), and S/N 500 at maximum and a coverage from 4000 A to 9200 A. Many spectra were acquired for all sample stars. The atmospheric parameters (Teff, log g, [Fe/H] and microturbulence velocities) have been obtained through an iterative and totally self-consistent procedure from Fe lines of the observed spectrum. The initial values of Teg were obtained from a (B-V) vs Teg calibration and log were determined from Hipparcos parallaxes and evolutionary tracks. The [O/Fe] abundances were derived by fitting synthetic spectra to the observed one. 

Radial velocities were measured by cross-correlation, using a synthetic spectrum as template. Individual spectra were shifted to rest wavelength and coadded. Effective temperatures were derived from the (V — I)o colours by means of the Alonso calibration [8], We assumed log g = 2.0 for all stars (estimated from isochrones) and with these parameters we fed the spectra to our automatic procedure for the determination of abundances [9], We found that the S/N ratio was too low to be able to determine reliably the microturbulent velocities, the weak Fe I lines could not be measured on many spectra. This resulted in a marked dependence of derived abundances on microturbulent velocities. It is well known that microturbulence is not a truly independent parameter but correlates with surface gravity and, more mildly also with effective temperature. By considering the large sample of stars studied by [10] one can be convinced that for all stars with 1.5 < logg < 3.0 (20 stars) there is no marked dependence from either Tefi or log g, and the mean value of the microturbulent velocity is 1.6 kms 1. For this reason we fixed the microturbulent velocity at 1.6 kms-1. 

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