Sampling apparatus for

Each grab sample is obtained fairly rapidly (15 to 30 s), and four grab samples constitute one rim a total of 12 grab samples is required for a complete series of three rims. An interval of 15 min between grab samples is required. The range of this method has been determined to be 2 to 400 mg of NO (as NO9) per dry standard cubic meter (without dilution). Figure 25-34 shows a schematic of the sampling apparatus for an NO source test. 

Inhalation toxicity studies are conducted in inhalation chambers. The complete system contains an apparatus for the generation of aerosol particles, dusts, or gas mixtures of defined composition and particle size, a chamber for the exposure of experimental animals, and a sampling apparatus for the determination of the actual concentration within the chamber. All these devices present technical problems that are difficult to resolve. For rat studies, a particle size of 4 microns is usually targeted. 

Aerosols used for inhalation therapy are generally packaged in containers with metered values. The standard procedure is to discharge the entire contents of the container for assay. For betamethasone dipropionate and betamethasone valerate topical aerosols, the contents are discharged into a volumetric flask and the propellants carefully boiled off. Precautions should be taken, as many of these propellants are flammable. The residue is diluted to volume with isopropanol-acetic acid (1000 1) and filtered [50]. Another approach is to discharge the contents into ethanol or dilute acid. An alternative is to immerse the canister in liquid nitrogen for 20 min, open the canister, evaporate the liquid contents, and dissolve the residue in dichloromethane. A unit spray sampling apparatus for pressurized metered inhalers has been described [51]. The components in an aerosol product that can be the cause of assay variance have been studied [52]. A method to quantify the volatile components of aerosol products has been developed [53]. 

To avoid any wall effect or perturbation effect that may occur with these methods, a sampling apparatus for the photographic technique has been proposed by Kawecki et al. (K5). Bubbles are extracted from the tank containing the dispersion by means of a tube connected to a small square-section column through which a continuous flow of liquid and bubbles rises. The flow rate is chosen high enough so that differences in the free-rise velocity of the bubbles do not affect the mean residence time of the bubbles in the column. The bubbles in the column are then photographed. 

In practice, optical and scanning electron microscopes are commonly used to view the shapes of crystals. Measurement can be performed offline by taking samples from the crystallizer. Therefore, care should be taken to avoid the complications associated with sampling. Apparatus for in-situ viewing of slurry without sampling is also available commercially. However, the resolution of such devices is limited to tens of microns due to the limitation of the optical focal depth. 

Figure 1 Typical sampling apparatus for determination of ozone (A) midget impinger (dimensions in mm), (B) annular de-nuder (cross-sectional view), and (C) gas scrubbing/aeration bottle (500 or 1000 ml).

Sampling apparatus for collecting tetraethyllead from polluted air. 

C (250° F) on a filtering medium. The sampling apparatus, however, may have to be modified to conform with the states definition of a particulate. For example, a state may define pai ticulate as any material collectible at stack conditions, a definition that would allow the filtering medium to be located in the stack. 

As the gas stream proceeds through the sampling apparatus, the particulate matter is trapped on a filter, the moisture is removed, and the volume of the sample is measured. Upon completion of samphng, the collec ted material is recovered and sent to a laboratory for a gravimetric determination or analysis. 

Sulfur Dioxide EPA Method 6 is the reference method for determining emissions of sulfur dioxide (SO9) from stationary sources. As the gas goes through the sampling apparatus (see Fig. 25-33), the sulfuric acid mist and sulfur trioxide are removed, the SO9 is removed by a chemical reaction with a hydrogen peroxide solution, and, finally, the sample gas volume is measured. Upon completion of the rim, the sulfuric acid mist and sulfur trioxide are discarded, and the collected material containing the SO9 is recovered for analysis at the laboratory. The concentration of SO9 in the sample is determined by a titration method. 

Apparatus for testing materials for heat-transfer applications is shown in Fig. 28-4. Here the sample is at a higher temperature than the bulk solution. 

The best precision attainable with present apparatus for reasonable counting intervals should correspond to a standard deviation near 0.02% for a major constituent in an ideal sample properly handled. In most x-ray emission spectrography, the standard deviation is 1% or greater. Much of this discrepancy must be traceable to the way in which samples are prepared, and handled in the spectrograph, manipulation of the... 

Fig. 6. Side-arm tube of the apparatus for the determination of the coefficients of the heterogeneous recombination, y, of atomic gases previously dissociated in the rf discharge zone. The heterogeneous recombination proceeds on the inner glass walls of the horizontal side-arm tube and on a catalytically active cylindric sample of the metal investigated (Smith-Linnett method).

Figure 1. Apparatus for the preparation of radical anions (11). On connection of the entire vessel to the vacuum system, traces of water and oxygen on the wall are removed by heating and discharging with a tesla coil. When the apparatus is filled with purified nitrogen through A, the weighed sample of the hydrocarbon is put into B through C, a piece of sodium is put into D, and dimethoxyethane is distilled into E, where a small amount of an Na-K alloy is added. After the system is again evacuated the solvent is distilled from E into B, the bulb E is,sealed off at F, and the sodium is sublimed to form a mirror on the wall of the bulb G. After tubes at C and H are sealed off, the apparatus is pumped to high vacuum for 1 hr and then sealed off at J. Then the solution of the hydrocarbon is poured from B into G. After a time varying from several minutes to several hours, a color is observed, and the sample is ready for optical and esr measurements.

Apparatus for Combustion of Samples Containing CiLL beled Pesticides for Residue Analyses, Agr. Food Chem. (1964) 12, 172. 

The development of modern surface characterization techniques has provided means to study the relationship between the chemical activity and the physical or structural properties of a catalyst surface. Experimental work to understand this reactivity/structure relationship has been of two types fundamental studies on model catalyst systems (1,2) and postmortem analyses of catalysts which have been removed from reactors (3,4). Experimental apparatus for these studies have Involved small volume reactors mounted within (1) or appended to (5) vacuum chambers containing analysis Instrumentation. Alternately, catalyst samples have been removed from remote reactors via transferable sample mounts (6) or an Inert gas glove box (3,4). 

Figure 4.6 shows an apparatus for the fluorescence depolarization measurement. The linearly polarized excitation pulse from a mode-locked Ti-Sapphire laser illuminated a polymer brush sample through a microscope objective. The fluorescence from a specimen was collected by the same objective and input to a polarizing beam splitter to detect 7 and I by photomultipliers (PMTs). The photon signal from the PMT was fed to a time-correlated single photon counting electronics to obtain the time profiles of 7 and I simultaneously. The experimental data of the fluorescence anisotropy was fitted to a double exponential function. 

Figure 4.6 Block diagram of the apparatus for the fluorescence depolarization measurement. The dashed and solid arrows indicate the light paths ofthe excitation pulse and the fluorescence from the sample. OBJ microscope objective, M mirror, L lens, DM dichroic mirror, LP long-pass filter, PH pin-hole, PBS polarizing beam splitter, P polarizer, PMT photomultiplier.

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