Sampling remote

Fiber-Optic Probes. Fiber-optic probes provide remote sampling capabilities to Raman instmmentation, are stable, and give reproducible signals. Their historical niche has been in environmental monitoring. More recently these probes have been used in chemical process control and related areas such as incoming materials inspection. 

Use of remote sampling, handling, and container opening techniques. This can be achieved with robots, or, more commonly, by using... 

Raman microscopy has the ability to investigate regions down to 1 pm, and, by the aid of fibre optics, remote sampling is possible. The molecular information... 

D. Under no circumstances will the notebook be taken or otherwise leave the laboratory unless there is data to be recorded at a remote site, such as at a remote sampling site, or unless special permission is granted by the supervisor. 

Sometimes random sampling is difficult to execute, as when a stream is being monitored with a time-activated automatic remote sample collection device. Under such conditions a random start or other superimposed random time element may be substituted. The efficiency of systematic sampling improves as the population becomes better understood. Both theoretical and experimental studies of this point have been made (14). 

Sampling mode effects The goal was to be able to measure at-line, with no sample preparation at all, using a fiber-optic probe or a remote sampling head. However, the area sampled by the hber-optic probe is much smaller than for the sample transport module. It was found that the remote (probe) spectra were very similar to the static (sample transport) spectra, but the baselines were shifted significantly higher and the absorbance peaks consequently reduced in intensity as before, the characteristic peak positions were not affected. Calibration models developed using spectra obtained with the hber-optic probe performed equivalently to those developed with the sample transport module. 

Even though the relative distribution remains constant, the total level of PAH decreases dramatically with distance from urban centers. Figure 4 shows a plot of the total PAH abundance in five marine sediment samples taken from Massachusetts Bay as a function of distance from Boston (10). One can see that there is a three order of magnitude decrease in the total abundance of PAH within 100 kilometers of Boston. At that point, the total PAH level is about 100 ppb remarkably, this is what we see in almost all other remote samples. 

A balloon-borne, open path, tunable diode laser spectrometer (21) provides a particularly elegant technique that combines the advantages of in situ and remote sampling. The radiation absorption path is defined by the laser on the balloon gondola and a retro reflector suspended up to 500 m below. Thus, a well-defined parcel of air is analyzed and the effects of sampling inlets are avoided. NO, NO , HN03, N20, and 03 have been measured simultaneously (22). 

It is likely that we will see increasingly numerous examples of such systems in applications as diverse as home clinical chemistry assay kits and remote sampling for environmental applications. The discussion here outlines general applications and some of the unique physical properties and fabrication considerations of film electrodes, and then focuses in greater detail on preparation and properties of widely used examples of metallic, carbon film, and semiconductor electrode materials. 

Sampling mode effects The goal was to be able to measure at-line, with no sample preparation at all, using a fiber-optic probe or a remote sampling head. However, the area sampled by the fiber-optic probe is much smaller than for the sample transport... 

A fast FID consists of a main control unit and two remote sampling heads (which house the FIDs). The dual channel nature of the instrument enables simultaneous real-time measurement in two locations allowing, for example, evaluation of catalyst performance. 

From a sample preparation point of view, it must be remembered that several of the methods may require processing in vacuum, which implies remote sample handling and manipulation from outside the test chamber. There is a wide variety of intricate commercial instrumentation available for this step, and most designs allow additional customization, depending on vacuum chamber configuration. 

Because of the machine s mechanical limitations, there is a limit of five components that can be analyzed at one time at about 24 remote sampling points.9... 

In all ranges of the infrared, the near, middle, and far infrared (NIR, MIR, and FIR) mainly the absorption of radiation by a sample is evaluated. Emission spectra are only rarely recorded, even though they are a powerful tool for solving problems which cannot be investigated by other methods investigations of remote samples (in astronomy and for environmental analysis), of reactions of substances on catalysts, and of layers on surfaces (Mink and Keresztury, 1988) (Sec. 3.3.1). Other techniques of investigating surface layers, e.g., ATR technique and ellipsometry in the infrared range, are described in Sec. 6.4. 

Remote sampling of up to 20 m makes the system attractive for the analysis of large items. On the other hand, the system is also useful for precision analyses both by atomic absorption and plasma spectrometric methods. The analysis of electrically non-conductive powders is also possible, where a mixture of the powder to be analyzed and copper powder in a ratio of about 1 5 can be made and briquetted into a pellet. This can be realized by using pressures of up to 80 Torr/cm2, as has been described for glow discharge work by El Alfy et al. [210], The mass ratio of analyte to copper may, however, differ considerably from one sample base to another. 

Johnes J. L., Dahlquist R. L. and Hoyt H. E. (1971) A spectroscopic source with improved analytical properties and remote sampling capacity, Appl Spectrosc 25 629—635. 

Two remote sampling probes of 0.635 centimeter I.D. TEFLON are located equal distance from each end wall and from each other. The probe inlet is located approximately 1.4 meters off the floor of the chamber. A third sample probe located in the 3.8 centimeter exhaust hole (Item 12) provides an occasional verification of mixing consistency within the chamber. Formaldehye measurements at all sample locations have always checked within the experimental precision of the analytical method (approximately 4% for a 60 liter air sample). Obviously, these probes provide a convenient way of sampling the air within the chamber without distrubing the established chamber equilibrium. 

Using optical fibers, mid-lR spectroscopy has been used for online analysis and remote sampling [84]. Fibers used in the mid-lR region are produced from oxides, chalcogenides, and halides of various elements. To be useful, the fibers must have IR radiation transmission capability over short distances. Like ATR crystals, fibers are based on the total reflection of radiation inside a material. 

Ratios of dissolved HHCB/AHTN are included in Table 2. The ratios for the Canadian samples (1.9 to 2.5) matched closely those reported for the North Sea, and other remote sampling locations and the US (Bester et al. 1998a Heberer et al. 1999 Osemwengie and Steinberg 2001), while those for the Swedish samples (3.7 to 5.3) were closer to highly contaminated samples from Berlin (Heberer et al. 1999 Fromme et al. 2001) and other STP-effluents (Dsikowitzky et al. 2002). 

Andrews, J. and Dallin, P. 2003. Getting to grips with the process Extractive and remote sampling . 

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