Indicator substance

Technical-grade chloroform generally contains one or more stabilizers, which vary according to specification requirements. The most common is 50 ppm 2-methyl-2-butene [513-35-9]. Other stabilizers are industrial methylated spirit (0.2%), absolute alcohol (0.6—1%), thymol, /-butylphenol, or -octylphenol (0.0005—0.01%). A representative technical quaUty chloroform contains the following amounts of the indicated substances (maximum) ... 

Names of compounds m small capital Utters indicate substances for which directions are given the numbers m bold face type refer to volumes of Organic Syntheses, numbers in italics refer to pages in those volumes on which preparative directions are given and num bers in Arabic refer to pages on which the compounds or subjects are mentioned in connection with other preparations For example Acetoacetic Ester 4 45 6, 36 indicates... 

In a precipitation reaction, an insoluble solid product forms when we mix two electrolyte solutions. When an insoluble substance is formed in water, it immediately precipitates. In the chemical equation for a precipitation reaction, we use (aq) to indicate substances that are dissolved in water and (s) to indicate the solid that has precipitated ... 

State what happens to the concentration of the indicated substance when the total pressure on each of the following equilibria is increased (by compression) ... 

All add solutions taste sour and are more or less corrosive and chemically quite reactive they react with most metals, many of which are corroded and dissolved by acids. Alkaline solutions, also chemically reactive, are caustic (they burn or corrode organic tissues), taste bitter, and feel slippery to the touch. Both acids and bases change the color of indicators (substances that change color, hue, or shade depending on whether they are in an acid or basic environment). 

We have also shown that the indirect SOD assays, which are the mostly used methods for demonstrating complex SOD activity, are not very reliable and if, they can be applied only upon considering possible cross reactions between indicator substance and the studied complex in their different oxidation forms, in which they may occur within the SOD catal5rtic cycle. The direct stopped-flow method, where the high excess of superoxide over complex can be utilized, is a better probe for... 

Strictly speaking, refers to any combination of psychiatric (or other) diagnoses, but increasingly used to indicate substance misuse plus a psychiatric condition, e.g. schizophrenia, depression... 

Paper chromatographic analyses of samples extracted with 0.5N sulfuric acid by M. A. Rogers. c x indicates substance was present, but quantity not measured. 

Determine the amount (in moles) of electrons needed to produce the indicated substance in an electrolytic cell (a) 5.12 g of copper from a copper(II) sulfate solution (b) 200 g of aluminum from molten aluminum oxide dissolved in cryolite (c) 200 L of oxygen gas at 273 K and 1.00 atm from an aqueous sodium sulfate solution. 

In former experiments (5) we have shown that chemical analysis for Amadori compounds (mainly consisting of fructose-glutamic acid) and isovaleralde-hyde, formed by Strecker degradation of the amino acids leucine and isoleucine, can be used for an early detection of undesirable quality changes caused by the Maillard reaction. In order to demonstrate the usefulness of these compounds as indicator substances for quality improvement of dried products, we performed drying experiments with carrots as an example of plant products. 

Indicator Substance used to detect the end-point of a titration, generally by changing the color of the titration mixture. 

There are also new methods suggested recently, but they are not yet commonly employed.5 One of them involves ion-selective field effect transistor as a sensor, which requires smaller measurement area compared to the glass electrode.10 Other possible methods are electron spin resonance imaging and confocal microscopy.5 11 12 They require treatment of the skin with an indicator substance, which penetrates into the epidermis and allows the pH to be detected in several layers simultaneously.12... 

First of all, from levels (1) and (2) the intention was to characterize and if possible to identify and quantify recycling-related (R) polymer components (migrants). Then, R-components with relatively high concentrations should serve as indicator substances to be monitored in migration measurements on level (3). The realization of this principle is demonstrated in Fig. 10-17. In the upper and middle gas chromatograms it compares the components extracted from a virgin and a R-PP cup. 

Determine a dose-response relationship or safe mixture level for the mixture of concern (or for its fractions) for future evaluation of sufficiently similar mixtures, for example, based on laboratory or held testing in combination with the use of one or more indicator substances. 

Many thousands of chemicals enter water bodies from anthropogenic sources. These chemicals have significantly different properties, which makes it impossible to monitor or measure such a variety. Consequently, when these water pollutants are considered, they are generally grouped into substance types, and a priority or indicator substance is used to estimate their presence. 

For each of the three species, the area under the peak is approximately proportional to the number of moles of the indicated substance in the sample. From other information, it is known that the molar ratio of methane (CH4) to nitrogen is 0.200. 

The major disadvantage of kinetic methods is that the change in concentration of the indicator substance must be measured not only with little error but also as a function of time. As mentioned, the inclusion of time as an experimental variable means that temperature must be carefully controlled and also the solution composition (as it affects activities of the reacting species). 

Integral methods Constant time In the fixed-time method of measurement the change in concentration of the indicator substance I [which could be [R] or [P] in Equation (21-2)] is measured twice to cover a preselected time interval (Figure 21-2). 

Integral methods Variable time In the variable-time method of measurement of the initial slope, the concentration of the indicator substance I is measured twice, and the time interval At required to bring about a preselected change in concentration A[I] is the important quantity (Figure 21-2, right). Since the change in concentration is a fixed preselected value, it can be incorporated with the constant in Equation (21-5) to give... 

Indications Substance abuse, opioid dependence, alcohol dependence... 

The indicator substance for iron determination is Tiron [4,5-dihydroxy-l,3-benzenedisulfonic acid, disodium salt] (Acros Organics, Geel, Belgium). The stock solution used to prepare the calibration samples contains Ig Fe/L (solution of Fe(N03)3-4aq in HNO3 0.5N) (Panreac Quimica, Barcelona, SP). 

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