Tracer for monitoring

Non Rare Earth SATs. Several candidates that meet these criteria have been found, and some of their applications are discussed by Kruger (5). Krugers discussion also contains an excellent accoimt of the early history of this field. In a series of experiments at the Pennsylvania State University, Jester and coworkers (6,7) have used Br" and I" to mimic the movement of soluble species in natural waters. In-EDTA complexes have been used by Behrens et al. (8) to monitor groundwater movement, while Dahl (9) has shown that In(N03)2 could be used to trace water stream patterns and pollutant dispersal in and around the harbor of a Norwegian town. Indium and scandium were used as stable activable tracers for monitoring in-plant movements of water in waste water treatment plants by Craft and Eicholz (10). The entire subject of industrial uses of activable tracers has been reviewed recently by Van Dalen and Wijkstra (II). 

Figure 10-169. Seif-reguiating heat tracer for pipe and vesseis. Some simpier designs have temperature monitoring and power controi. (Used by permission Bui. (P6909) H53398 4/94. Raychem Corporation, Chemeiex Division.)...

Thierrin J, GB Davis, C Barber (1995) A ground-water tracer test with deuterated compounds for monitoring in situ biodegradation and retardation of aromatic hydrocarbons. Ground Water 33 469-475. 

A munber of organic compounds are suitable for use as tracers in a process for monitoring the flow of subterranean fluids. The following traces have been proposed benzene tetracarboxylic acid, methylbenzoic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, naphthalene-trisulfonic acid, alkyl benzene sulfonic acid, alkyl toluene sulfonic acid, alkyl xylene sulfonic acid, a-olefin sulfonic acid, salts of the foregoing acids, naphthalenediol, aniline, substituted aniline, pyridine, substituted pyridines [883]. 

Choice of tracer. Any material can be used as a tracer for a response study if (1) its flow follows accurately the flow of the process stream (2) it can be monitored with reasonable ease and (3) it can be introduced in sufficient quantity without disturbing the flow of the process stream. 

Improvement of the techniques for monitoring local instantaneous concentrations down to the viscous dissipation microscale (e.g. spatial and time resolution of conductivity probes), development of new techniques (e.g. optical, radioactive tracer methods). 

Some possible criticisms of the use of radiotracers for monitoring the uptake and release of cocaine are that the tracer chemically reacts with the hair matrix or contains radiolabeled impurities which show preferential binding. Both criticisms are unlikely because (1) the radiotracer never exceeds 1% of the urdabeled drug, and (2) hair exposed to drugs without the radiotracer and analyzed by GC/MS show the parent drug present in amounts indicated by the radiotracer analysis. 

The nature of the tracer dictates the detection system. For the liquid phase, quite often the tracers (e.g., NaCl, H2S04, etc.) are such that the detection probe is directly inserted into the reactor and continuous monitoring of the concentration at any fixed position is obtained by means of an electrical conductivity cell and a recorder. In this case, no external sampling of liquid is necessary. If the tracer concentration measurement requires an analytical procedure such as titration, etc., sampling of the liquid is required. For the solid phase, a magnetic tracer is sometimes used. The concentration of a solid-phase tracer can also be measured by a capacitance probe if the tracer material has a different dielectric constant than the solid phase. In general, however, for solid and sometimes gas phases, some suitable radioactive tracer is convenient to use. The detection systems for a radioactive tracer (which include scintillation counters, a recorder, etc.) can be expensive. Some of the tracers for the gas, liquid, and solid phases reported in the literature are summarized in Table 3-1. 

However, there is a remarkable disproportion between the three main areas occupied today by RC, namely hazards, process design/optimization and for monitoring the physico-chemical transformations. If there is an extensive activity in the field of hazards, often with little contribution to increased safety, probably less than 20% of the process development laboratories use calorimeters for process design and optimization very little interest is shown for the use of heat released as a tracer for physico-chemical transformations since RC is still barely used in synthesis laboratories where reactions and process procedures are initiated. 

De Agostini A, Mascaro L, Pizzocaro C, et al. 1993. 85Sr contaminant as a reliable tracer of 89Sr for monitoring urinary radioactivity in patients treated with 89Sr for bone metastasis. J Nucl Biol Med 37 38-44. 

Chloride and bromide are the tracers of choice. Tracers must be applied at the time of pesticide application, so that the movement of the tracer can be directly correlated to the movement of pesticide. However, in a more detailed study, Tennyson and Settergren (38) found that bromide moved more rapidly in soil-water than would be expected from the laboratory determined soil hydraulic conductivity (K). Radioactive materials, organic dyes, gases, and fluorocarbons are not recommended for use as tracers. The fluorocarbons have been used successfully, though they have not been used extensively to date (39) After the application of pesticide and tracer, the procedures previously outlined should be followed for monitoring soil and ground water. 

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