Detection coefficient

Figure 11.8A shows the radioactivity emitted by a mixture of two independently decaying species 1 and 2, detected with detection coefficients Cj and C2 (independent and not necessarily identical, but identical here, for the sake of simplicity). 

As shown in figure 11.8B, because the ratio A1/A2 becomes constant, the slopes of the combined decay curves of the two radionuclides attain a constant value corresponding to the half-life of the longer-lived term (curves a and b in figure 11.8B). Moreover, assuming identical detection coefficients for the two species, their radioactivity ratio also attains a constant value of... 

Figure 11,8 Composite decay curves for (A) mixtures of independently decaying species, (B) transient equilibrium, (C) secular equilibrium, and (D) nonequilibrium, a composite decay curve b decay curve of longer-lived component (A) and parent radio nuclide (B, C, D) c decay curve of short-lived radionuclide (A) and daughter radionuclide (B, C, D) d daughter radioativity in a pure parent fraction (B, C, D) e total daughter radioactivity in a parent-plus-daughter fraction (B). In all cases, the detection coefficients of the various species are assumed to be identical. From Nuclear and Radiochemistry, G. Friedlander and J. W. Kennedy, Copyright 1956 by John Wiley and Sons. Reprinted by permission of John Wiley and Sons Ltd.

Assuming identical detection coefficients for the two species, the radioactivity ratio obviously reduces to 1. This condition, known as secular equilibrium, is illustrated in figure 11.8C for ty2, = °° and ti/2 2 = 0.8 hr. Secular equilibrium can be conceived of as a limiting case of transient equihbrium with the angular coefficient of decay curves progressively approaching the zero slope condition attained in figure 11.8C. 

Since the postionization probability oc2 of an analyzed species X is determined by the postionization method and thus becomes a constant of the specific SNMS apparatus, the product t]x can be combined to one apparatus constant D, which is the detection coefficient for X in the particular SNMS system. Equation [2] then reads ... 

Note that in liquid phase chromatography there are no detectors that are both sensitive and universal, that is, which respond linearly to solute concentration regardless of its chemical nature. In fact, the refractometer detects all solutes but it is not very sensitive its response depends evidently on the difference in refractive indices between solvent and solute whereas absorption and UV fluorescence methods respond only to aromatics, an advantage in numerous applications. Unfortunately, their coefficient of response (in ultraviolet, absorptivity is the term used) is highly variable among individual components. 

The detectable limits are given for samples such as they are introduced into the apparatus they should be previously diluted in order to be nebulized. It thereby is useful to apply a dilution coefficient, usually at least 10. The dilution depends on the sample viscosity. 

The traditional method for investigating the forces originating in the body of the bolt, which is based on measuring the torque of the nut, can detect only the bolts with a very great lack of body force since tbe friction coefficient worsens with time. 

As a result, the interference of the reflectional wave is shown the change for the position both the defects and the interfaces, and the size of the defect. And, the defect detection quantitatively clarified the change for the wave lengths, the reflection coefficient of sound pressure between materials and the reverse of phase. 

An application of correlation analysis is the detection of related chemical de.scriptors when analyzing chemical data, correlation analysis should be used as a first step to identify those descriptors which are interrelated. 1 f two descriptors are strongly correlated, i.e, the correlation coefficient of two descriptors exceeds a certain value, e.g., r > 0.90, one of the descriptors can be excluded from the data set. 

As the medium is still further diluted, until nitronium ion is not detectable, the second-order rate coefficient decreases by a factor of about 10 for each decrease of 10% in the concentration of the sulphuric acid (figs. 2.1, 2.3, 2.4). The active electrophile under these conditions is not molecular nitric acid because the variation in the rate is not similar to the correspondii chaise in the concentration of this species, determined by ultraviolet spectroscopy or measurements of the vapour pressure. " ... 

Silicones have been detected in water from various rivers and in effluent from wastewater treatment faciUties. They are barely detectable in water from municipal treatment faciUties. Water solubiUty (S) of siUcones has been found to correlate with the octanol—water partition coefficients for a... 

A two-site immunometric assay of undecapeptide substance P (SP) has been developed. This assay is based on the use of two different antibodies specifically directed against the N- and C-terminal parts of the peptide (95). Affinity-purified polyclonal antibodies raised against the six amino-terminal residues of the molecule were used as capture antibodies. A monoclonal antibody directed against the carboxy terminal part of substance P (SP), covalently coupled to the enzyme acetylcholinesterase, was used as the tracer antibody. The assay is very sensitive, having a detection limit close to 3 pg/mL. The assay is fiiUy specific for SP because cross-reactivity coefficients between 0.01% were observed with other tachykinins, SP derivatives, and SP fragments. The assay can be used to measure the SP content of rat brain extracts. 

Control of an evaporator requires more than proper instrumentation. Operator logs snould reflect changes in basic characteristics, as by use of pseuao heat-transfer coefficients, which can detect obstructions to heat flow, hence to capacity. These are merely the ratio of any convenient measure of heat flow to the temperature drop across each effect. Dilution by wash and seal water should be monitored since it absorbs evaporative capacity. Detailed tests, routine measurements, and operating problems are covered more fuUy in Testing Procedure for Evaporators (loc. cit.) and by Standiford [Chem. Eng. Prog., 58(11), 80 (1962)]. 

RMC can be selectively extracted into butyl acetate. Concentration coefficient 50 was achieved. Factors affecting accuracy and reproducibility of the proposed method were investigated. Method is simple and fast. Detection limit is 0,3 p.g/1 for P(V). 

There have been also found the quantitative characteristics of the methods. They are as follows for HPLC method the linearity is 0.1 ng to 2 ng the detecting limit is 0.1 ng the limit of the quantitative estimation makes up 0.0004 mg/kg a coefficient of variation is 2.74% for the chromatodensitometry method the linearity is 2 ng to 10 ng the detecting limit is 0.6 ng the coefficient of variation is 2.37%. The data obtained have been treated using a regressive analysis. 

Liquid chromatography was performed on symmetry 5 p.m (100 X 4.6 mm i.d) column at 40°C. The mobile phase consisted of acetronitrile 0.043 M H PO (36 63, v/v) adjusted to pH 6.7 with 5 M NaOH and pumped at a flow rate of 1.2 ml/min. Detection of clarithromycin and azithromycin as an internal standard (I.S) was monitored on an electrochemical detector operated at a potential of 0.85 Volt. Each analysis required no longer than 14 min. Quantitation over the range of 0.05 - 5.0 p.g/ml was made by correlating peak area ratio of the dmg to that of the I.S versus concentration. A linear relationship was verified as indicated by a correlation coefficient, r, better than 0.999. 

Coefficient of variation FMEA Detectability Rating Frequency... 

---