Quantitative data, instrumental

Finally, for situations in which it is not clear that exposure is and will continue to be below the limit values, a detailed survey with a measurement strategy is required. The methods used are based mostly on instruments for sampling the environment in order to obtain reliable measurements of workplace air concentrations. In general, the measurement strategy must consider the most efficient use of resources for the purpose of obtaining quantitative data on exposures by having a clear idea of what the data will be used for or whether it meets the specified need. For example, if the data pertain to peak exposures, these peaks have to be assessed according to the STEL requirements, if any. 

The data on probabilities given in this example are for illustration only, and do not represent actual data for these components. Some quantitive data on the reliability of instruments and control systems is given by Lees (1976). Examples of the application of quantitive hazard analysis techniques in chemical plant design are given by Wells (1996) and Prugh (1980). Much of the work on the development of hazard analysis techniques, and the reliability of equipment, has been done in connection with the development of the nuclear energy programmes in the USA (USAEC, 1975) and the UK. 

Active Air Sampling Active air sampling provides quantitative data because air at a known flow rate is impacted on a strip of nutrient media, followed by incubation of the nutrient strips and enumeration of colonies. Common active air sampling instruments include the slit-to-agar impact sampler and the centrifugal (Reuter) sampler. 

Approximately 1 g polymer and 0aQ6 M Cr(acac). were dissolved in CDCl. to prepare solutions for ySi and JC NMR spectroscopy. NMR spectra were run on a Varian XL-200 FT-NMR instrument. To aid in obtaining quantitative data, the solution was doped with 0.06 M chromium acetylacetonate [Cr(acac) )] to remove possible signal artifacts resulting from long spin-lattice relaxation times (T s) and tt> nucleay Overhauser effect, well-known features associated with 3Si and JC NMR spectroscopy. This permits quantitative signal acquisition. From the literature (16) and additional work done in this laboratory, it was expected that Cr(acac) would be an inert species. A solution of HMDZ (2.04 g, 12.67 mmole),... 

Both new and experienced users can take advantage of software to lead them through instrument set-up and data acquisition. Automated quantitation routines are available to calculate compound amounts in samples. These routines offer complete flexihihty to generate custom report formats. By integrating retention time information and internal or external cahhration curves can he calculated. Quantitation data can he exported to popular spreadsheet programs. 

These steroids are components of the profile of Kushnir et al. [44, 45] and are discussed below in Hormonal Steroid Profiles . They were analyzed as the oxime derivatives by ESI on an API 4000 instrument. The MRM transitions for pregnenolone oxime were 332—>86 and 300, and for the d4 internal standard 336—>90 and 334. Transitions for 17HP were 348—>330 and 312, and for the d3 internal standard 351—>333 and 315. The publication gives quantitative data for Tanner stage 1-5 male and female children and for several age groups up to 52 years. 

True profile analysis requires scanning over the whole mass range for the acquisition of all data on excreted compounds. Quantitation has been more challenging on a quadrupole instrument because total ion current peaks are seldom a single component and extracted-ion chromatograms (EICs) when recovered from scanned data are of poor quality due to the lower sensitivity of scanning GC-MS. Thus, we developed profile analysis based on SIM of selected analytes but tried to ensure the components of every steroid class of interest were included. For ion traps the fundamental form of data collection (in non-MS/MS mode must be full -scans). Thus, the quantitative data produced are EICs obtained from scanned data. The EICs are of the same ions used for SIM in quadrupole instruments and the calibration external standards are the same. 

More than one probe gas usually is used to study a given specimen because, as shown by Equation 1, the probe atomic mass cannot be less than the sample atomic mass, and the peak resolution decreases as the difference between these masses increases. Semi-quantitative data is received if the instrument is calibrated with samples of known surface composition. Qualitative data is available readily from using Equation 1. 

To be able to produce quantitative data, an internal standard and external standards are required. Internal standardization corrects for possible instrument drift or changes in the efficiency of the ablation and thus improves the... 

In this way, the fault tree can be quantified, which makes this technique very powerful for the reliability analysis of protection systems. The prerequisite is the availability of statistical reliability data of the different devices and instruments that is often difficult to obtain for multi-purpose plants, where devices can be exposed to very different conditions when changing from one process to another. Nevertheless, if the objective is to compare different designs, semi-quantitative data are sufficient. 

Ion selective membranes are the active, chemically selective component of many potentiometric ion sensors (7). They have been most successfully used with solution contacts on both sides of the membrane, and have been found to perform less satisfactorily when a solid state contact is made to one face. One approach that has been used to improve the lifetime of solid state devices coated with membranes has been to improve the adhesion of the film on the solid substrate (2-5). However, our results with this approach for plasticized polyvinylchloride (PVC) based membranes suggested it is important to understand the basic phenomena occurring inside these membranes in terms of solvent uptake, ion transport and membrane stress (4,6). We have previously reported on the design of an optical instrument that allows the concentration profiles inside PVC based ion sensitive membranes to be determined (7). In that study it was shown that water uptake occurs in two steps. A more detailed study of water transport has been undertaken since water is believed to play an important role in such membranes, but its exact function is poorly understood, and the quantitative data available on water in PVC membranes is not in good agreement (8-10). One key problem is to develop an understanding of the role of water uptake in polymer swelling and internal stress, since these factors appear to be related to the rapid failure of membranes on solid substrates. 

A more sophisticated instrument is the Farrand VIS-UV Chromatogram Analyser CFigure 3) that can also be used to measure the fluorescence spectra as well as to obtain reliable quantitative data. This particular instrument is equipped with a Xenon lamp that emits a continuous spectrum of wavelengths. It has two monochromators and two filters, for both the excitation and emission modes and can be operated either in double-beam ratio or single beam. 

In most experiments, scientists collect quantitative data, which is data that can be measured with instruments. They also collect qualitative data, descriptive information from observations other than measurements. 

Refs. [i] Garrison JD, Roeder SBW (1999) Environmental measurement. In Webster JG (ed) The measurement, instrumentation and sensors handbook. CRC Press, Boca Raton, pp 73-7-73-9 [ii] Wyszecki G, Stiles WS (2000) Color science - Concepts and methods, quantitative data and formulae. Wiley, New York... 

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