Quality, of specimens

X-Ray fluorescence (XRF) analysis favorably differs from other instmmental techniques by rapidity, automation ability, selectivity, accuracy. Quality of specimen obtained from sample to be analyzed has influence to the accuracy. 

There ai e noted the most convenient, simple and chip methods, which ensure the high quality of specimens and can be easily combined with different techniques for analytical pre-concentration of impurities. In particulaidy, it is proposed to make specimens in the form of gel, film or glass in the case of XRF analysis of concentrates obtained by low-temperature crystallization of aqueous solutions. One can prepai e film or organogel specimens from organic concentrates obtained by means of extraction of impurities by organic solvent. Techniques for XRF analysis of drinking, natural and wastewater using considered specimens ai e adduced. 

E2l5 Meites, S. and Glassco, K.M. (1985). Studies on the quality of specimens obtained by skin-puncture of children. 2. An analysis of blood-collecting practices in a pediatric hospital. Clin. Chem. 31, 1669-1672. 

In a few patients, backflow from blood tubes into veins occurs owing to a decrease in venous pressure. The dangerous consequences of this occurrence may be prevented if only sterile tubes are used for collection of blood. Backflow is minimized if the ai m is held downward and blood is kept from contact with the stopper during the collection procedure. To minimize problems if backflow should occur and to optimize the quality of specimens- especiaUy to prevent cross contamination with anticoagulants—blood should be collected into tubes in the following order (1) blood cul-... 

These changes should only be used as a guide, as the environmental conditions, length of time from death to specimen collection, and quality of specimen can affect the extent of redistribution. 

A test for evaluating ihe chemical quality of grades A, Bl, B2 and B3 by resistance to H2SO4. A specimen is placed in 95-96% H2SO4 and the temperature raised to 300°C in 7 mm. The flashing is due to a sudden increase in the rate of formation of PbS04 and should not happen below 285°C, or 300°C for lead for use at elevated temperatures. 

In the absence of a required retention period, the final disposition of any study materials should be documented. When samples of test and reference items and specimens are disposed of before the expiry of the required retention period for any reason, this should be justified and documented. Samples of test and reference items and specimens should be retained only as long as the quality of the preparation permits evaluation. 

In a lOOkV TEM, useful specimens can range in thickness from 20nm to 0.5 pm. For micro analysis, the thinner the specimen the better the quality of the information that can generally be obtained. 

If a laboratory is unable to do accurate parasitology because of either the types of procedures offered or the quality of personnel available, it should arrange to have specimens appropriately prepared and submitted to a reference laboratory. 

This can be accomplished using standard electophoretic and spectrophotometric methods. Researchers frequently note substantial variation in the quality of hybridizations obtained. Heavy background levels, scratches, and fingerprints are common contributors to hybridization variation. Once again, replicates for each RNA specimen permits discarding of bad arrays and serves to increase the precision of the data collected. 

Apart from the short beam shear test, which measures the interlaminar shear properties, many different specimen geometry and loading configurations are available in the literature for the translaminar or in-plane strength measurements. These include the losipescu shear test, the 45°]5 tensile test, the [10°] off-axis tensile test, the rail-shear tests, the cross-beam sandwich test and the thin-walled tube torsion test. Since the state of shear stress in the test areas of the specimens is seldom pure or uniform in most of these techniques, the results obtained are likely to be inconsistent. In addition to the above shear tests, the transverse tension test is another simple popular method to assess the bond quality of bulk composites. Some of these methods are more widely used than others due to their simplicity in specimen preparation and data reduction methodology. 

The structures of agarose, iota- and kappa-carrageenan have been determined by x-ray fiber diffraction (24-27). The quality of the diffraction data obtained from each of these three specimens varies considerably and the way in which these data are used in structure determination is outlined here. Diffraction patterns from oriented specimens of agarose, and kappa- and iota-carrageenan are shown in Figure 6 (28). The molecular repeat distances derived from these patterns are listed in Table I. 

In addition when it is necessary to process a large number of specimens per day, taking hours over a single specimen is clearly not a practical approach. The use of MRI to examine fresh, unfixed fetal rat and rabbit heads from embryo-fetal development (EFD) studies has already been proposed (6) (see Note 1) and the compromise between image quality and speed of acquisition that is necessary under these circumstances examined. MRI is now considered to have the potential to be an acceptable alternative to current methods after throughput was increased by scanning multiple specimens in parallel with careful optimization of scan parameters. 

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