Safe sampling volume

The safe sampling volume (SSV) is usually defined as 70% of the 5% breakthrough volume (ISO, 2001,16017-1). If, for a given air sample, the sample volume... 

After obtaining the retention volume at several temperatures, the log of retention volume is plotted vs. 1/°K and the curve extrapolated to 20 °C or calculated by least squares linear regression. The breakthrough volume, the point at which the compound is first detected, is dependent on the sensitivity of detection and the efficiency of the column (peak width), but the retention volume is independent of these factors. Taking into account the unknown effects of coadsorbed compounds under true atmospheric conditions, the maximum safe sampling volume (MSSV) can be estimated as being one-half the V,. 

Though the use of transmission geometry is common for many other spectroscopic techniques, it has not been widely nsed for Raman spectroscopy [39] In this case, illumination and collection optics are on opposite sides of the sample. The actual generation and travel of Raman photons through the sample is convoluted, but it is safe to conclude that the bulk of the sample is probed [40,41]. The large sample volume probed results in reduced subsampling errors. In one example, the use of the transmission mode enabled at least 25% reduction in prediction error compared to a small sampling area probe [42]. The approach is insensitive... 

Adsorption gravimetry lends itself to in-situ outgassing (up to 500°C with our equipment) but can only accommodate one sample at a time. A major advantage only obtained with the special assembly making use of a sinker is the permanent measurement of the density of the gas phase it allows not only to make at any time a correct buoyancy correction but it also allows to provide the users of adsorption manometry equipment with the data they need to make a safe void volume correction. 

The amount of RNA to be injected into the oocyte is an important consideration because oocytes have a finite capacity to export (Zasloff, 1983 Dargemont and Kuhn, 1992 Jarmolowski et al, 1994 Pokrywka and Goldfarb, 1995 Simons et al, 1996), import (Fischer et al, 1993), or retain (Terns and Dahlberg, 1994 Boelens et al, 1995 Terns et al, 1995) specific RNA species in the nucleus. It is generally safe to inject 1-2 fmol of RNA without saturating RNA transport pathways, but the effect of RNA concentration on transport should ideally be assayed for a given test RNA. Thus, it is important both to measure accurately the concentration of RNA and to inject an accurate sample volume (Ceriotti and Colman, 1995). 

Ideally three separate determinations should be made on every sample, each determination in duplicate, necessitating a sample volume of 2-2.5 liters. The minimum sample volume that can safely be used is 1.5 liters. Samples should be transferred to polyethylene bottles with spigots coming from the base or fitted with a syphoning device of plastic tubing. They should not be stored for more than 1-2 hr and should be kept at sea temperature. 

Samples can be removed for analysis, phase volumes can be measured to determine mixture composition and molar volumes (70), and phase boundaries can be measured. Many different configurations of view cells have been proposed. Some are capable of pressures ia excess of 100 MPa (14,500 psi). The cell coateats may be viewed safely through the sapphire wiadow by use of a mirror, video camera, or borescope. 

It is soluble in about 5 volumes of 70 per cent, alcohol. This ester has the character of being saponified much more slowly than most other esters, so that in any determination in which it is involved it is necessary to saponify the sample for two hours before it is safe to consider the reaction complete. This fact also assists in determining whether terpinyl acetate is present as an adulterant in natural essential oils, for if the saponification value as determined by thirty minutes saponification is materially lower than that as determined by a two hours saponification, it may be fairly safely inferred that terpinyl acetate or some similar ester is present. 

With a modern variable-wavelength or PDA detector, it is safe to use a maximum absorbance of up to 1.0-1.5 absorbance units (AU). A typical UV detector today should have a baseline noise in the order of 10 micro absorbance units (10 AU). Therefore, modern UV detectors should have a dynamic range of 4-5 orders of magnitude. The sample concentration and injection volume can be adjusted to make it possible to quantify the major component and impurities at the 0.05% level in the same chromatographic run without changing detection wavelength, sample concentration, or injection volume. 

Thus, for the determination of the energy potential of a sample, it is essential to use closed pressure resistant cmcibles for these experiments. This is true for DSC, but holds also for other instruments. Experience has shown that gold plated cmcibles with a volume of 50 pi and resistance to pressures up to 200 bar are best suited for safely studies. These crucibles are commercially available. 

Wear goggles and protective gloves and clothing. Dissolve a 50 mg sample in 200 mL of water. Add 4 g of diethyldithiocarbamate and stir for 24 hours. The yellow precipitate that forms is a deactivated complex which can safely be discarded. Remove the precipitate by filtration and wash the filtrate into the drain with a large volume of water.3-... 

The fact that Carson et al. found larger errors for comparable orifice sizes can probably be accounted for by their smaller chamber (approximately one-third in volume). Exact comparison is difficult because of uncertainty in the amount and nature of the sample surface. In any case, considering the experimental variability, the pressure-drop error apparently can be safely neglected (3%) if the orifice is 1 mm. or less in diameter, which was the case for all the work reported here. 

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