Sample collection tools

The modem HPLC system is a very powerful analytical tool that can provide very accurate and precise analytical results. The sample injection volume tends to be a minor source of variation, although fixed-loop detectors must be flushed with many times their volume in sample to attain high precision. Assuming adequate peak resolution, fluorimetric, electrochemical, and UV detectors make it possible to detect impurities to parts per billion and to quantitate impurities to parts per thousand or, in favorable cases, to parts per million. The major sources of error in quantitation are sample collection and preparation. Detector response and details of the choice of chromatographic method may also be sources of error. 

A large variety of tools, utilizing both chemical and physical methods, are available to the experimentalist for rate measurements. Some can be classified as ex-situ techniques, requiring the removal and analysis of an aliquot of the reacting mixture. Other, in-situ, methods rely on instantaneous measurements of the state of the reacting system without disturbance by sample collection. 

That different components of blood must be stored at different temperatures should be considered in the study design. Most samples retain their integrity for years if stored in nitrogen tanks (-196°C ) or deep freezers (-80°C) (Gunter 1997 Landi and Caporaso 1997). In addition to the preservation of biologic components in the collected samples, it is important to ensure that measurement of environmental pollutants in the samples is not confounded by contaminants in the containers or tools used for sample collection. Prescreening of the materials may be necessary, depending on the toxicant of interest. 

Researchers have found tremendous variability in weed seedbank numbers. Recent research in Iowa counted from 113 million to 613 million weed seeds per acre (280 million to 1515 million/ha) (Hartzler, 1993), but there was as much variation in size of the weed seedbank within individual fields as there was between different fields. Because of the extreme variability of seedbanks within individual fields, Hartzler concluded that measurements of the weed seedbank do not appear to be an accurate tool for predicting weed populations. He suggested that the precision of such measurements could probably be improved by dividing fields into smaller units for samples and by increasing the number of samples collected. However, he concluded that the cost and time demands of this type of sampling would be prohibitive. 

Groundwater samples collected with direct push sampling tools... 

All tools should be washed with alcoholic nitric acid, water and be well dried before use. They should be placed under laminar flow at least half hour before starting sample collection. 

The Tools and Techniques Sampling, Sample Collection, and Sample Handling... 

The IAEA helps the ALMERA network of laboratories to maintain their readiness by coordination activities, by development of standardized methods for sample collection and analysis, and by conducting interlaboratory comparison exercises and proficiency tests as a tool for external quality control. 

Until 1987, numbers of samples for tbe inter-comparison program were 10-20% of the total samples collected by the local laboratories but were unified to 20 samples for each laboratory. As a result of the 15-year inter-comparison, it has been recognised that inter-comparison is a useful tool for resolving technical problems sometimes encountered and for upgrading the quality of analysis and measurements performed by prefectural hygiene institutes/laboratories. They might also serve to ensure the safety of nuclear power plants. 

This study has demonstrated that precise chemical analysis is a powerful tool for the characterization and provenance determination of Middle Eastern obsidian. Thirteen to 15 chemically distinctive groups were distinguishable in geological source samples collected from eight source... 

Summary The use of the on-line FT-Raman spectroscopy for monitoring a multi-step hydrosilylation reaction combines all the advantages of an on-line analytical tool (like real time measuring results, a direct view into the reaction, and no off-line sample collection) with the requirements for the application of technology in production plants, e. g., low calibration effort within a wide temperature range, stable calibration, simple system handling for the operator, small sized equipment at the reaction vessel, and no contact with the reaction media. 

Molecular fluorescence has been shown to be a valuable tool for studying the binding of certain metal ions to both isolated humic materials (1-4) and natural organic matter present in samples collected from lakes, rivers and other bodies of water (5,6). Paramagnetic metal ions tend to reduce or quench fluorescence which has been demonstrated for Cu " (1-5), Co " (4,6), Mn " (4), Ni (1), Fe " and Fe " (7) with various samples of humic materials. Diamagnetic metal ions, on the other hand, may quench, show no effect or even enhance humic material fluorescence depending on the metal, the source of the humic material and other experimental factors (1,8-13)... 

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