Continuous monitoring method

Chu, K.D. and P.K. Hopke, Continuous Monitoring Method of the Neutralizing Phenomena of Polonium-218, Presented at the 78th Annual Meeting of the Air Pollution Control Association, Detroit, Michigan, (June 1985). 

Continuous monitoring methods based on amperometric (Nikolic et al. 1992) or spectrophotometric (Kuban 1992 Ma and Liu 1992) techniques for the quantification of free cyanide are also available. Ion chromatography with amperometric determination provides good sensitivity (2 ppb) and selectivity for free cyanide and the weak complexes of cadmium and zinc (Rocklin and Johnson 1983). Postcolumn derivatization and fluorescence detection provides low detection limits as well (0.1 ppb) (Gamoh and Imamichi 1991). 

Determmation of reaction rate involves the kinetic measurement of the amount of change produced in a defined time interval. Both fixed-time and continuous-monitoring methods are used to measure reaction rates. In the fixed-time method, the amount of change produced by the enzyme is measured after stopping the reaction at the end of a fixedtime interval. In the continuous-monitoring method, the progress of the reaction is monitored continuously. These two methods have different advantages and limitations. To appreciate these, it is necessary to consider the way in which the rate of an enzymatic reaction varies with time. 

Continuous-monitoring methods for assay of TR-ACP activity are based on the principle introduced by Hillmann in which a-naphthoi released from its phosphate ester forms a colored product with the stabilized diazonium salt of 2-amino-5-chlorotoluene-1,5-naphthalene disulfonate (Fast Red TR). The introduction of alcohols, such as 1,5-pen-tanediol, accelerates the reaction and increases sensitivity by acting as phosphate acceptors in transfer reactions. The addition of sodium tartrate inhibits the sensitive isoenzymes (i.e., prostatic and lysosomal ACPs) if they are present in the sample. 

Earlier TG/MS data for residual moisture in freeze-dried biological products were obtained by the continuous monitoring method of Chiu and Beattie using a DuPont 990 thermal analysis system interfaeed with a glass tee to a DuPont 21-104 mass spectrometer and the methodology... 

Currently, continuous monitoring methods are aimed at generating on-demand data for determining the condition of materials and for detecting the presence of corrosion. These monitoring methods for metallic systems rely on sensors that fall into several categories ... 

Badjagbo K, Moore S, Sauve S. Real-time continuous monitoring methods for airborne VOCs. Trends Anal Chem. 2007 26 931 0. 

A first study of reaction kinetics with ACOMP was made for the semibatch emulsion polymerization of MMA at 70 °C [50]. The use of continuous monitoring method described in the previous sections offered a robust means of determining the characteristic features of the starved and flooded monomer conditions and identifying them during the experiments. 

This monitoring method should make it possible to decide wether to continue with the pressurization of the vessel or to stop it, based on real-time and reliable detection and location of any potentially hazardous defect which is evolving. 

Environmental Applications Although ion-selective electrodes find use in environmental analysis, their application is not as widespread as in clinical analysis. Standard methods have been developed for the analysis of CN , F , NH3, and in water and wastewater. Except for F , however, other analytical methods are considered superior. By incorporating the ion-selective electrode into a flow cell, the continuous monitoring of wastewater streams and other flow systems is possible. Such applications are limited, however, by the electrode s response to the analyte s activity, rather than its concentration. Considerable interest has been shown in the development of biosensors for the field screening and monitoring of environmental samples for a number of priority pollutants. 

Automated analyzers may be used for continuous monitoring of ambient poUutants and EPA has developed continuous procedures (23) as alternatives to the referenced methods. Eor source sampling, EPA has specified extractive sampling trains and analytical methods for poUutants such as SO2 and SO [7446-11-9] sulfuric acid [7664-93-9] mists, NO, mercury [7439-97-6], beryUium [7440-41-7], vinyl chloride, and VOCs (volatile organic compounds). Some EPA New Source Performance Standards requite continuous monitors on specified sources. 

Waste Gas Streams. Several methods of decomposing phosgene in waste gas streams are used. The outlet gas from the phosgene decomposition equipment is continuously monitored for residual phosgene content to ensure complete decomposition. 

The Reich test is used to estimate sulfur dioxide content of a gas by measuring the volume of gas required to decolorize a standard iodine solution (274). Equipment has been developed commercially for continuous monitoring of stack gas by measuring the near-ultraviolet absorption bands of sulfur dioxide (275—277). The deterrnination of sulfur dioxide in food is conducted by distilling the sulfur dioxide from the acidulated sample into a solution of hydrogen peroxide, foUowed by acidimetric titration of the sulfuric acid thus produced (278). Analytical methods for sulfur dioxide have been reviewed (279). 

Uranium and thorium are the first members of natural radioactive chain which makes their determination in natural materials interesting from geochemical and radioecological aspect. They are quantitatively determined as elements by spectrophotometric method and/or their radioisotopes by alpha spectrometry. It is necessary to develop inexpensive, rapid and sensitive methods for the routine researches because of continuous monitoring of the radioactivity level. 

None of the foregoing methods will tell the frequency or duration of exposure of any receptor to irritant or odorous gases when each such exposure may exceed the irritation or odor response threshold for only minutes or seconds. The only way that such an exposure can be measured instrumentally is by an essentially continuous monitoring instrument, the record from which will yield not only this kind of information but also all the information required to assess hourly, daUy, monthly, and annual phenomena. Continuous monitoring techniques may be used at a particular location or involve remote sensing techniques. 

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). 

For some hood types, measurements usually seen as indirect method, are used to measure the hood s performance to determine regulatory compliance. For example, regulations specify minimum and maximum face velocities for laboratory fume hoods and static pressure (negative) inside enclosed hoods. Continuously monitoring instruments can be connected to alarms that sound when the measurement is outside the specified limits. 

In the case of a continuous monitoring a special device must generally be used. This apparatus is characteristic of a method which is used and is described further (continuous monitoring). 

Ultrasound and X-ray equipment are examples of diagnostic medical devices. In-vitro medical devices are distinguished from other diagnostic medical devices, in that a specimen must first of all be removed from the donor. A device worn by a diabetic that continually monitors their glucose via a non-invasive method (near-infra-red energy emissions) would be just regulated as a medical device, whereas a glucosemonitoring device that used a lancet to obtain a blood sample would be an IVD. 

The continuous monitoring of liquid lithium for O, C, H and H uses electrochemical cells based on Tho2-Y203 electrolytes and diffusion meters. No continuous method for N analysis is yet available . ... 

Hi) Specialized Analytical Methods. Analytical methods for metallic impurities are well documented and are not covered here. A major advance in the continuous monitoring of impurities in liquid sodium down to the lowest levels of detection has been the development of analysis using electrochemical cells. Oxygen analysis in sodium may be carried out using a cell of the type... 

Two other methods of monitoring impurity levels in loop or reactor systems are based on the equilibration of metals with the solution of the nonmetal in sodium. Oxygen may be evaluated by the vanadium wire equilibrium method " and carbon by the use of stainless steel or nickel equilibration. Neither of these methods gives continuous monitoring of the impurity, but each is employed in a regular sampling system. 

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