Laboratory environment

The ability to control pressure in the laboratory environment is a powerful tool for investigating phase changes in materials. At high pressure, many solids will transfonn to denser crystal stmctures. The study of nanocrystals under high pressure, then, allows one to investigate the size dependence of the solid-solid phase transition pressures. Results from studies of both CdSe [219, 220, 221 and 222] and silicon nanocrystals [223] indicate that solid-solid phase transition pressures are elevated in smaller nanocrystals. 

A number of techniques have been developed for the trace analysis of siUcones in environmental samples. In these analyses, care must be taken to avoid contamination of the samples because of the ubiquitous presence of siUcones, particularly in a laboratory environment. Depending on the method of detection, interference from inorganic siUcate can also be problematic, hence nonsiUca-based vessels are often used in these deterrninations. SiUcones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and tetrahydrofuran (THF)... 

In the area of consumer products, amperometric glucose sensors hold high potential. Industrially, process monitors for the manufacture of consumer chemicals are under development. However, replacement of defective reference electrodes, which in a laboratory environment may be trivial, may be prohibitively difficult m vivo or in an industrial process environment. 

In the past ten years laboratory workers have become increasingly conscious of safety in the laboratory environment. We have therefore in three places in Chapter 1 (pp. 3 and 33, and bibliography p. 52) stressed more strongly the importance of safety in the laboratory. Also, where possible, in Chapters 3 and 4 we draw attention to the dangers involved with the manipulation of some hazardous substances. 

Different filter media, regardless of the specific application, are distinguished by a number of properties. The principal properties of interest are the permeability of the medium relative to a pure liquid, its retention capacity relative to solid particles of known size and the pore size distribution. These properties are examined in a laboratory environment and are critical for comparing different filter media. 

An example may show how the different concepts come into effect in a real-life laboratory environment. This example is based on column selections that many laboratories use for ordinary, general-purpose work. 

Toxicity Test (Bioassay). Organisms representative of those to be protected are exposed to the test water under rigorously controlled conditions, usually in a laboratory environment. In this test the organisms, normally fish, are exposed for a standard time period in aquaria to various dilutions of waste or river water while some physiological parameter is carefully monitored to determine fish response. Behavior is also observed. 

The pressure difference between the source of the mass spectrometer and the laboratory environment may be used to draw a solution, containing analyte and matrix material, through the probe via a piece of capillary tubing. When an adequate spectrum of the first analyte has been obtained, the capillary is simply placed in a reservoir containing another analyte (and matrix material) and the process repeated. This may therefore be used as a more convenient alternative to the conventional static FAB probe and this mode of operation may also benefit from the reduction in suppression effects if the analyte is one component of a mixture. 

Nakhleh, M. B. (1994). Chemical education research in the laboratory environment - how can research uncover what students are learning Journal of Chemical Education, 77(3), 201-205. 

Adapting the system to a mobile unit involved redesigning the instrumentation for portability and mounting it into a 3 A x 5-ft steel cart. A major requirement for this unit was containment of the Line-Lite laser, optical elements, and detection module in a clean laboratory environment. Other requirements included high ground clearance, accessibility to electricity within 100 ft, and durable construction. The entire mobile unit can be powered by a 5-kW gasoline generator. 

Reliability This encompasses factors such as the laboratory environment and organization, equipment design and maintenance, personnel training, skills and experience, design and handling of the analytical method, etc. 

The experimental conditions, even though under a controlled laboratory environment, are not too different from what may be observed in a closed drum of this material exposed to ambient temperatures for prolonged periods of time. This paper emphasizes that using only the onset of an exotherm as an indication of the point of no return for a reactive chemical system may be insufficient, as pressure may accumulate even at temperatures much lower than the anticipated exotherm. 

Resnick L., Veren K., Salahuddin S.Z., Tondreau S. Markham P.D. (1986) Stability and inactivation of HTLV-in/LAV under clinical and laboratory environments. J Am Med Assoc, 255, 1887-1891. 

Field fortification (commonly referred to as field spiking) is the procedure used to prepare study sample matrices to which have been added a known amount of the active ingredient of the test product. The purpose for having field fortification samples available in a worker exposure study is to provide some idea of what happens to the test chemical under the exact environmental field conditions which the worker experiences and to determine the field storage stability of the test substance on or in the field matrix materials. Field fortifications do not serve the purpose of making precise decisions about the chemical, which can better be tested in a controlled laboratory environment. The researcher should not assume that a field fortification sample by its nature provides 100% recovery of the active ingredient at all times. For example, a field fortification sample by its very nature may be prone to cross-contamination of the sample from environmental contaminants expected or not expected to be present at the field site. 

In a GLP-compliant laboratory, a data system must meet explicit requirements guaranteeing the validity, quality, and security of the collected data. Operational qualification (OQ) must be performed after any new devices are installed in the laboratory system and whenever service or repair are performed. The role of OQ is to demonstrate that the instrument functions according to the operational specifications in its current laboratory environment. If environmental conditions are highly variable, OQ should be checked at the extremes in addition to normal ambient conditions. Performance qualification (PQ) must be performed following any new installation and whenever the configuration of the system has been changed. PQ demonstrates that the instrument performs according to the specifications appropriate for its routine use. 

Field demonstration. A field demonstration is always necessary to supplement a bench-scale evaluation, as some technical issues cannot be undertaken in a laboratory environment. In addition, field data help address nontechnical issues. Proper planning is critical for the implementation of a successful demonstration to ensure that all monitoring equipment, construction, and quality control procedures are in place. 

Having familiarity with the tools of financial analysis, those seeking the introduction of LIMS technology into their laboratory environments will be well prepared if such financial considerations are the ultimate arbiters of budget approval decisions. A... 

There remain challenges to overcome in the use of FLIM and FRET in the general laboratory environment. A clear understanding of the nature of fluorescence decay is necessary for the correct interpretation of FLIM data and care must be taken to use negative controls appropriately. The contamination of lifetime data by... 

Radioactive contaminations of individual construction materials, as well as the laboratory environment, were measured and the impact on detector performance was determined by Monte Carlo computations [83], The background sources which were considered are ... 

It is vital to know if the analyte is present in the laboratory environment, adsorbed on the glassware, in reagents or in the demineralized water used in the analysis. These are all potential sources of contamination. This is particularly important when carrying out new determinations and for trace analysis. It is also important to ensure that your colleagues working nearby are not using chemicals that could affect your determination. 

To recognize the characteristics of a laboratory environment which can affect the performance of equipment and hence influence the validity of measurements. 

The laboratory environment can affect the quality of measurements in ways other than direct contamination. 

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