Sampling probes used

Table I. Sample probes used to develop knowledge base of Module 3 for specification of analytical HPLC column, and mobile phase constituents.

Figure 2. Schematic of sampling probe used for mass balance study...

The ability of currently used aircraft probes to accurately sample aerosols has been questioned. Huebert et al. (8) conducted a comparative study of several different types of aerosol probes, all mounted on the same aircraft. The results suggested that substantial losses of particles occurred in all of the inlet systems. Because of the limited nature of the study, however, the causes of the aerosol losses could not be identified. The results of the Huebert study prompted a workshop to reexamine the entire issue of aerosol sampling from aircraft (9). An important conclusion of the workshop was that currently there is insufficient knowledge to adequately describe important characteristics of airflow and particle trajectories at flight speeds of aerosol sampling probes used on aircraft. 

Adsorbed DNA from sample probed using biotinylated... 

I. J. Lowe and M. Englesberg, "A fast recovery pulsed nuclear magnetic resonance sample probe using a delay line," Rev. Sci. Instrum. 45, 631-639 (1974). 

Particle probe. A,-probe, gas probe and alkaU metal sampling probe used to monitor a 20 MWe CFB combustor... 

One of the advantages of Raman spectroscopy is that remote sampling can be accomplished using fiber-optic sampling [42,43], A block diagram of a remote sampling probe using fiber optics is shown in Fig. 5.13. 

The calibration graph for the probe using a strength machine, has been shown in Fig. 7 It can be observed that the dependence of indications of the device of Wirotest type on the loading is linear within the proportionality limit scope. After unloading the indications do not return to zero, but show own stress caused in effect of plastic deformation of the tested sample... 

Fig. 4. Schematic of the Closed Container Sampling technique used in the Baxter PARAMAX analy2er showing (a) the collection tube with bar-coded label being brought into sampling position under the caimula (b) the tube raised so that the caimula has penetrated the stopper (c) the sample sensing probe coming through the caimula to aspirate the exact volume required for each assay and (d) after sampling, where the tube is lowered away from the cannula.

When the operating conditions are uniform and steady (there are no fluctuations in flow rate or in concentration of CO in the gas stream), the continuous sampling method can be used. A sampling probe is placed in the stack at any location, preferably near the center. The sample is extracted at a constant sampling rate. As the gas stream passes through the sampling apparatus, any moisture or carbon dioxide in the sample gas stream is removed. The CO concentration is then measured by a nondispersive infrared analyzer, which gives direct readouts of CO concentrations. 

The liquid was applied and dried on cellulose filter (diameter 25 mm). In the present work as an analytical signal we took the relative intensity of analytical lines. This approach reduces non-homogeneity and inequality of a probe. Influence of filter type and sample mass on features of the procedure was studied. The dependence of analytical lines intensity from probe mass was linear for most of above listed elements except Ca presented in most types of filter paper. The relative intensities (reduced to one of the analysis element) was constant or dependent from mass was weak in determined limits. This fact allows to exclude mass control in sample pretreatment. For Ca this dependence was non-linear, therefore, it is necessary to correct analytical signal. Analysis of thin layer is characterized by minimal influence of elements hence, the relative intensity explicitly determines the relative concentration. As reference sample we used solid synthetic samples with unlimited lifetime. 

Auger electron spectroscopy (AES) is a technique used to identify the elemental composition, and in many cases, the chemical bonding of the atoms in the surface region of solid samples. It can be combined with ion-beam sputtering to remove material from the surface and to continue to monitor the composition and chemistry of the remaining surface as this surface moves into the sample. It uses an electron beam as a probe of the sample surface and its output is the energy distribution of the secondary electrons released by the probe beam from the sample, although only the Ai er electron component of the secondaries is used in the analysis. 

In the direct insertion technique, the sample (liquid or powder) is inserted into the plasma in a graphite, tantalum, or tungsten probe. If the sample is a liquid, the probe is raised to a location just below the bottom of the plasma, until it is dry. Then the probe is moved upward into the plasma. Emission intensities must be measured with time resolution because the signal is transient and its time dependence is element dependent, due to selective volatilization of the sample. The intensity-time behavior depends on the sample, probe material, and the shape and location of the probe. The main limitations of this technique are a time-dependent background and sample heterogeneity-limited precision. Currently, no commercial instruments using direct sample insertion are available, although both manual and h ly automated systems have been described. ... 

On heating at 225°C, 5-aUykyclohexa-l,3-diene, A, undergoes intramolecular cycloaddition to give the tricyclic nonene B. The mechanism of formation of B was probed using the deuterium-labeled sample of A which is shown. Indicate the position of deuterium labels in product B if the reaction proceeds by (a) a [2 - - 2] cycloaddition or (b) a [4 -t- 2] cycloaddition. 

TTie system can be used for continuous measurement of the mass concentration at a single point for up to 12 hours, for traverse measurements of stack particulate mass concentrations using sample probe extensions, with the mass transducer up to 6 m in the stack, or for intermittendy measuring particulate mass concentrations of emission gases for long-term readings (e.g.. 30-sec samples every 60 minutes. ... 

FIGURE 9.16 Resilience values for chlorobutyl rubber (CIIR), butadiene rubber (BR), unfilled natural rubber (NR), filled natural rubber (SRB), and polyurethane (PU) samples tested using a Shore rebound resibometer, an Instron compression tester and a scanning probe microscope (SPM). (From Huson, M.G. and Maxweb, J.M.,... 

ESCA Sample Pretreatment. Samples were pelleted and cut to fit into a rectangular depression in an ESCA sample probe similar in design to one used by Hercules (16). The portion of the probe holding the catalyst sample could be withdrawn into an outer cylinder and sealed under an atmosphere of the pretreatment gas. For pretreatment the calcined samples were exposed to a hydrogen flow at one atmosphere and heated to AOO C. After this pretreatment the sanqile was withdrawn into the insertion tube, sealed in the pretreatment gas, inserted into the ESCA, evacuated, and then the ESCA spectra were recorded. A similar procedure was followed for the uncalcined catalysts except that the temperature was first increased in hydrogen flow to SOO C and held at this temperature for 3 to 4 hours the sample was then heated to 400 C and held at this temperature for 18 hours. 

To probe the formation of coke we conducted TPO measurements on samples previously used in the butene TPD experiments. The TPO profiles corresponding to catalyst INiSZ(s) are shown in Fig. 6. Significant evolution of CO2 was detected, indicating the formation of coke during the adsorption/desorption of 1-butene. The INiSZ(s) catalyst exhibited almost twice as much CO2 as the unpromoted SZ sample. 

In addition to being smooth, it is preferable that the soil surface be firmly packed. This is because loose soil is not always retained in large-diameter sampling probes. Firming of the soil surface may be accomplished using a turf roller or equivalent. Alternatively, the soil surface may be prepared in advance of study initiation to allow rainfall or irrigation to settle and firm the soil. This latter approach also allows soil surface depressions to be observed and avoided when laying out the test plots. 

LC-NMR hyphenation consists of a liquid chromatograph (autosampler, pump, column and oven) and a classical HPLC detector. The flow of the detector is brought via an interface to the flow-cell NMR probe. Using commercial NMR flow-cells with volumes between 40 and 180 p,L, in connection with microbore columns or packed capillaries, complete spectra have been provided from 1 nmol of sample. These micro-cells allow expensive deuterated solvents to be used, and thus eliminate solvent interference without excessive cost. The HPLC eluent can be split in order to allow simultaneous MS detection. 

The 5-mm tube held in the sample probe is indicative of the sample size used in an NMR instrument— typically some fraction of a milliliter. Typical analyte quantities dissolved in this volume range from 10... 

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