Analytical equivalence

The last type of precision study is reproducibility, which is determined by testing homogeneons samples in mnltiple laboratories, often as part of interlaboratory crossover stndies. The evalnation of reprodncibility results often focuses more on measnring bias in resnlts than on determining differences in precision alone. Statistical eqnivalence is often nsed as a measnre of acceptable interlaboratory resnlts. An alternative, more practical approach is the nse of analytical equivalence, in which a range of acceptable resnlts is chosen prior to the study and used to judge the acceptability of the results obtained from the various laboratories. 

Analytical equivalence the acceptability of the results obtained from... 

Complete knowledge regarding the structure of the interface would consist of information regarding the arrangement of all the particles or what is the analytical equivalent, the variation of the actual or perturbed concentrations of the species with distance from the reference plane. Such knowledge would be on the microscopic level. 

Attainable detection limits depend on the amount of analyte that enters the ICP per second, the efficiency of aerosol conversion into analyte ions in the ICP, and the transmission efficiency of ions from the plasma to the MS detector. The detection limits also depend on the variation of the background and the integration time. Typical pneumatic nebulizer/spray chamber systems operated at sample uptake rates from 0.1 to 2.0 mL/min introduce an amount of analyte equivalent to that in 10 to 30 JiL/min of sample solution into the ICP. At a sample uptake rate of 1 mL/min, only 1% to 2% of the analyte enters the plasma most of the sample is lost in the spray chamber and exits through the drain. Concentration based detection limits can be improved by approximately a factor of 10 by using a high-... 

As shown in Equation (17.9), a mole of hydrochloric acid is produced per mole of chlorine gas that reacts. Chlorination uses up the disinfectant, so this reaction would be driven to the right and any mole of chlorine gas added will be consumed. Thus, if a mmol/L of the gas is dosed, this will produce a mmol/L of HCl. This is equivalent to one mgeq of the acid, which must also be equivalent to a mgeq of alkalinity. The analytical equivalent mass of alkalinity in terms of CaCOj is 50 mg CaCOs per mgeq. Thus, the mmol/L of hydrochloric acid produced will need 50 mg/L of alkalinity expressed as CaCOs for its neutralization. Or, simply, one mmol of hydrochloric acid requires 50 mg of alkalinity expressed as CaCOs for its neutralization. 

A fundamental requirement for all coulometric methods is 100% current efficiency that is, each faraday of electricity must bring about chemical change in the analyte equivalent to one mole of electrons. Note that 100% current efficiency can be achieved without direct participation of the analyte in electron transfer at an electrode. For example, chloride ion may be determined quite easily using poten-tiostatic coulometry or using coulometric titrations with silver ion at a silver anode. Silver ion then reacts with chloride to form a precipitate or deposit of silver chloride. The quantity of electricity required to complete the silver chloride formation serves as the analytical variable. In this instance, 100% current efficiency is realized because the number of moles of electrons is essentially equal to the number of moles of chloride ion in the sample despite the fact that these ions do not react directly at the electrode surface. 

An analytical equivalent to the Gilliland correlation is expressed in equation form (Molokanov et al., 1972) ... 

The methods of coulometry are based on the measurement of the quantity of electricity involved in an electrochemical electrolysis reaction. This quantity is expressed in coulombs and it represents the product of the current in amperes by the duration of the current flow in seconds. The quantity of electricity thus determined represents, through the laws of Faraday, the equivalents of reactant associated with the electrochemical reaction taking place at the electrode of significance. In the analytical chemistry sense, the process of coulometry, carried out to the quantitative reaction of the analyte in question, either directly or indirectly, will yield the number of analyte equivalents involved in the sample under test. This will lead to a quantitative determination of the analyte in the sample. Analytical coulometry can be carried out either directly or indirectly. In the former the analyte usually reacts directly at the surface of either the anode or cathode of the electrolysis cell. In the latter, the analyte reacts indirectly with a reactant produced by electrolytic action at one of the electrodes in the electrolysis cell. In either case, the determination will hinge on the number of coulombs consumed in the analytical process. 

The analytical equivalent hydraulic conductivity tensor can be expressed in this case as following ... 

That this should be analytically equivalent to the second law may perhaps be seen in a general way by reflecting that if there were no limitation upon the direction of heat transfers, such as the second... 

This is the amount of analyte spiked on the sampling device which allows recovery of an amount of analyte equivalent to the detection limit of the analytical procedure. (See Backup Data Section 4.2). 

Predicting Elevated Temperature Ratings Based on Producer s Available Data and Limited Heat Aging and Analytical Equivalency Validation at UL... 

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