INDEX monitoring

Ryan, R.P. and Terry, C.E., Eds., Toxicology Desk Reference The Toxic Exposure and Medical Monitoring Index, 5th CD-ROM ed., Hemisphere Publishing Co., Washington, D.C., 1999. 

Ryan RP, Terry CE. Toxicology desk reference The toxic exposure medical monitoring index Vol 1-3, Bristol, PA Taylor Francis, 1996. 

Fukaya Y, Saito I, Matsumoto T, et al. 1994. Determination of 3,4-dimethylhippuric acid as a biological monitoring index for trimethylbenzene exposure in transfer printing workers. Int Arch Occup Environ Health 65 295-297. 

By studying the coal face gas emission characteristics, dividing the gas emission evaluation index into three types static index, dynamic index and key monitoring index. For different types of index. 

MORE TO rXPLORE www.who.i nt/reproductive-health/global monitoring/ index.html... 

In Germany, basic principles of HBM have been defined by the German Human Biomoiutoring Commission (http //www.umweltbundesamt.de/gesundheit-e/monitor/ index.htm). The Commission was established in 1992 at the Federal Environment Agency. Two kinds of guidance values in HBM have been developed the reference... 

In LC, the most common means for monitoring the eluant is to pass it through a cell connected into an ultraviolet spectrometer. As substances elute from the column, their ultraviolet absorption is measured and recorded. Alternatively, the refractive index of the eluant is monitored since it varies from the value for a pure solvent when it contains organics from the column. 

Attenuated total reflection, on which atr—ftir is based, occurs when the rarer medium is absorbing and is characterized by a complex refractive index (40). The absorbing characteristics of this medium allow coupling to the evanescent field such that this field is attenuated to an extent dependent on k. The critical angle in the case of attenuated total reflection loses its meaning, but internal reflection still occurs. Thus, if the internally reflected beam is monitored, its intensity will reflect the loss associated with the internal reflection process at the interface with an absorbing medium. 

Source sampling of particulates requites isokinetic removal of a composite sample from the stack or vent effluent to determine representative emission rates. Samples are coUected either extractively or using an in-stack filter EPA Method 5 is representative of extractive sampling, EPA Method 17 of in-stack filtration. Other means of source sampling have been used, but they have been largely supplanted by EPA methods. Continuous in-stack monitors of opacity utilize attenuation of radiation across the effluent. Opacity measurements are affected by the particle size, shape, size distribution, refractive index, and the wavelength of the radiation (25,26). 

U.S. EPA Environmental Monitoring Methods Index, including regulatory Hsts, analytical methods, detection and regulatory limits coverage of worldwide environmental information... 

Optical properties also provide useful stmcture information about the fiber. The orientation of the molecular chains of a fiber can be estimated from differences in the refractive indexes measured with the optical microscope, using light polarized in the parallel and perpendicular directions relative to the fiber axis (46,47). The difference of the principal refractive indexes is called the birefringence, which is illustrated with typical fiber examples as foUows. Birefringence is used to monitor the orientation of nylon filament in melt spinning (48). 

Another classification of detector is the bulk-property detector, one that measures a change in some overall property of the system of mobile phase plus sample. The most commonly used bulk-property detector is the refractive-index (RI) detector. The RI detector, the closest thing to a universal detector in lc, monitors the difference between the refractive index of the effluent from the column and pure solvent. These detectors are not very good for detection of materials at low concentrations. Moreover, they are sensitive to fluctuations in temperature. 

By monitoring the insulation condition of the windings during maintenance, at least once a year, which can be carried out by measuring (a) the polarization index (Section 9.5.3) and (b) the dielectric loss factor, tan S (Section 9.6) and making up the insulation as in Section 9.5.2, when the condition of the insulation is acceptable and only its level is less than permissible. 

Filter plugged index to monitor the condition of each stages of filters... 

Axial proximity probes are another means of monitoring rotor position and the integrity of the thrust bearing. A typical installation is shown in Figure 21-11. In this case two positions are being monitored one at the thrust runner, and one at the end of the shaft near the centerline. This method detects thrust-collar runout and also rotor movement. In most cases this ideal positioning of the probes is not possible. Many times the probes are indexed to the rotor or other convenient locations and thus do not truly show the movement of the rotor with respect to the thrust bearing. 

The ISO philosophy for the assessment of hot environments is to use a simple, fast method of monitoring the environment, based on the wet bulb globe temperature (WBGT) index (ISO 7243). If the WBGT value exceeds the provided reference value, or if a more detailed analysis is required, then ISO 7933 provides an analytical method of assessment. 

The evaluation methods could be direct, e.g., measuring a containment index, or indirect, e.g., measuring pressure loss or velocity distribution. The direct methods are used to measure the performance of a hood or an inlet during periodic preventive maintenance. Indirect methods are used for verifying or checking on a daily basis (routine checks). How often each method is used depends on the availability of instrumentation and qualified personnel, since direct measurement of a hood s performance can be both expensive and difficult. On the other hand, indirect methods are usually easier to use and can sometimes include inexpensive, continuously monitoring instruments (pressure gauges or velocity indicators). 

Figure 14.17 Schematic diagram of the on-line coupled LC-GC system VI, valve foi switcliing the LC column outlet to the GC injector V2, valve for switching the LC column to back-flush mode V3, LC injection valve RI, refractive index monitor detector UV, ulti avio-let monitor detector FID, flame-ionization detector.

An infrared beam is directed through a crystal of refractive index (ni) onto a sample of smaller refractive index (n2). The intensity of the reflected beam is monitored as a function of the wavelength of the incident beam. These absorptions are used to identify the chemical structure. ATR has a sampling depth of about 0.3-3.0 microns. 

The dead point is obtained by including in the sample a trace of an unretained solute or, more often, one of the components of the mobile phase. For example, when using a methanol water mixture as the mobile phase, the dead point is obtained from the elution of a pure sample of methanol. The pure methanol can often be monitored, even by a UV detector, as the transient change in refractive index resulting from the methanol is sufficient to cause a disturbance that is detectable. 

---