Spiking prove

Having established matrix effects - does spiking prove necessary in every case ... 

Having Established Matrix Effects - Does Spiking Prove Necessary in Every Case ... 

Independent Assays for Provings Virus Removal. Retrovimses and vimses can also be present in culture fluids of mammalian cell lines (15,24). Certainly the absence of vims can be difficult to prove. Model vimses, eg, NIH Rausher leukemia vims and NZB Xenotropic vims, were spiked into fluids being purified, and their removal subsequently vaUdated when subjected to the same purification sequence as used for the product. 

Ultramodern techniques are being applied to the study of corrosion thus a very recent initiative at Sandia Laboratories in America studied the corrosion of copper in air spiked with hydrogen sulphide by a form of combinatorial test, in which a protective coat of copper oxide was varied in thickness, and in parallel, the density of defects in the copper provoked by irradiation was also varied. Defects proved to be more influential than the thickness of the protective layer. This conclusion is valuable in preventing corrosion of copper conductors in advanced microcircuits. This set of experiments is typical of modern materials science, in that quite diverse themes... combinatorial methods, corrosion kinetics and irradiation damage... are simultaneously exploited. 

The safety of the ZEBRA battery has been proven extensively by abuse testing overheating, overcharging, short-circuiting of battery terminals and of cell groups, crash tests on the battery itself by dropping it at 50 km h 1 onto a pole or spike, and crash tests of cars with built-in ZEBRA batteries at 50 kmh-1 [10]. The results of abuse testing prove the ZEBRA battery to be a safe battery system. 

Once the MDL has been calculated, it is important to prove that the chosen analytical procedure is practically capable of detecting the analyte(s) at the MDL. To prove the practicality of the MDL, the analyst should spike triplicate sub-samples of an untreated control sample at the MDL, extract the fortified control samples and analyze them on the instrument. Well defined chromatographic peaks would prove the validity of the calculated MDL. 

In the last few years, we have seen the application of isotope dilution methodologies to some new analytical fields. One of these is elemental speciation , where the aim is to determine individual chemical species in which an element is distributed in a given sample. IDMS has also proved its usefulness in element speciation, in which either species-specific or species-unspecific spikes can be used. For example, species-specific IDMS is nowadays used in several laboratories as an effective tool to validate analytical procedures for speciation and to investigate and document eventual interconversion between species. In addition, the study of induced variations in the isotopic composition of a target element can also provide insight into various (bio)chemical and physical processes isotopic analysis is, therefore, also of increasing importance in biological studies. 

The same protocol could also be used to clean up an effluent form the textile industry. Figure 7 (Fig. 8 of the original) shows that the investigated triazines were retained on the MIP and the baseline was quite clean. An alternative method using conventional hydrophobic SPE produced a much worse baseline. Phenylurea herbicides were also spiked to the samples to check the selectivity of the procedure for triazines. The MIP proved selective (i.e., did not retain the phenylureas) while the traditional sorbent was not selective and also retained the phenylureas. 

The total time for analysis—including sample preparation, separation, and detection—was 12.5 minutes for one sample, or 22 minutes for the sample and spiked sample. In tests on actual Hanford nuclear-waste samples, comparing results from the automated analyzer method to laboratory ICP-MS determinations, the analyzer method proved to be accurate in the determination of total "Tc. 

Wennrich [167] optimised important accelerated solvent extraction parameters, such as extraction temperature and time, using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 °C and ten-minute extractions performed three times proved optimal. Two accelerated solvent extraction-solid-phase microextraction procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits. 

Interfacing the TEA to both a gas and a HPLC has been shown to be selective to nitro-based explosives (NG, PETN, EGDN, 2,4-DNT, TNT, RDX and HMX) determined in real world samples, such as pieces of explosives, post-blast debris, post-blast air samples, hand swabs and human blood, at picogram level sensitivity [14], The minimum detectable amount for most explosives reported was 4-5 pg injected into column. A pyrolyser temperature of 550°C for HPLC-TEA and 900°C for GC/TEA was selected. As the authors pointed out, GC uses differences in vapour pressure and solubility in the liquid phase of the column to separate compounds, whereas in HPLC polarity, physical size and shape characteristics determine the chromatographic selectivity. So, the authors reported that the use of parallel HPLC-TEA and GC-TEA techniques provides a novel self-confirmatory capability, and because of the selectivity of the technique, there was no need for sample clean-up before analysis. The detector proved to be linear over six orders of magnitude. In the determination of explosives dissolved in acetone and diluted in methanol to obtain a 10-ppm (weight/volume) solution, the authors reported that no extraneous peaks were observed even when the samples were not previously cleaned up. Neither were they observed in the analysis of post-blast debris. Controlled experiments with handswabs spiked with known amounts of explosives indicated a lower detection limit of about 10 pg injected into column. 

The data produced during the instrumental analysis must be filtered to obtain only data that (a) prove the identity of a spiking chemical, (b) are of good quality, and (c) meet the OPCW reporting requirements for the respective instrumental analysis (see reference 8), for inclusion in the final report. The initial filtering of data is performed by the instrument operators, checked by responsible scientists, and double-checked by the compiler of the report, in the scientific judgment step. 

In both the trial and official proficiency tests, the ROPs for sample preparation validated in the round-robin tests proved themselves useful methods to recover CWC-related chemicals spiked at trace level. The participating laboratories had prepared the samples following the ROPs, though sometimes with slight modifications. Many of the laboratories were also able to identify degradation products... 

In laboratory tests using simulated HLW solution spiked with fission product tracers, Am and Cm, the denitration step proved to be a sensitive process, but Am/Cm recoveries of ca. 90% in the aqueous supernate could be realized under optimized conditions. Decontamination factors (DF) > 1000 for Zr, Nb, Mo, and 100 for Ru and Fe were obtained in the precipitation step. The solvent extraction cycle gave > 98% recovery of Am/Cm and DF > 10 for rare earths, Sr and Cs. Appreciable decontamination was also obtained for Zr/Nb (DF = 20), Ru (50), U (650), Pu (250), Np (800) and Fe (420). The ion exchange cycle served mainly for Am-Cm concentration and for removal of DTPA and lactic acid based on tests with europium as a stand-in for trivalent actinides, concentration factors of about 50 could be expected under optimized conditions. 

Figure 11. For the purpose of this discussion, the most important features in the spectrum are the two methanol peaks labeled b and c, where b is the methyl proton resonance for methanol trapped within the hexameric sphere, and c is the methyl proton resonance for methanol in the bulk solvent. The identity of these peaks was proved by a spiking experiment in which additional methanol added to the NMR tube had the effect of increasing the intensity of peak c. Similar results were obtained in acetone-, DIVISOR and toluene- - It should also be noted that NMR spectra for hexamer 8 synthesized in ethanol or 2-propanol also showed two sets of resonances for each inequivalent proton in the ethanol or 2-propanol molecules. Indeed, in a pressurized NMR sample tube we observed no change in the intensities of peaks b and c at 150 °C in acetone- -...

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