Reproducibility, precision

Analytical techniques (including method, accuracy, precision, reproducibility, robustness, limits of detection). 

Table 4.3 Relationship between precision (reproducibility) and concentration level ...

The ability of a tPLC system to produce the same values of retention time and peak areas for analytes of interest is determined by evaluating the precision obtained under standardized conditions and analytical methods. The precision (reproducibility) values obtained are functions of the autosampler, cartridge, and detectors employed. Due to the parallel design of the tPLC system described in this chapter, reproducibility evaluations of retention time and peak area involved comparisons of results obtained for these parameters for consecutive runs performed in the same column and across different columns. 

In the context of an analytical method to establish the accuracy, precision, reproducibility, response function and the specificity of the analytical method with reference to the biological matrix to be examined and the analyte to be quantified. 

Repeatability Intermediate precision Reproducibility Limit of detection + ... 

Precision measures how close data points are to each other for a number of measurements under the same experimental conditions. According to the ICH, precision is made up of three components repeatability, intermediate precision, and reproducibility. The term ruggedness, which has been used in the USP, incorporates intermediate precision, reproducibility, and robustness. 

Experiments 10-27 are designed to check the autosampler injection precision, pump repeatability and detector/system linearity. One programs the system to automatically inject multiple replicate volumes of a certified test standard. One typically injects 6-10 replicates per volume. The standard component s peak areas are used for calculated injection precision (reproducibility) and system linearity whereas, the retention times are used to calculate pump repeatability. 

Control sample a representative batch of drug substance (or drug product). Typically, control samples are tested in all analyses to ensure consistency in method performance across different runs. Sometimes, they are used as part of the system suitability test to establish the run-to-run precision (e.g., intermediate precision, reproducibility). 

Some laboratory errors are more obvious than others, but there is error associated with every measurement. There is no way to measure the true value of anything. The best we can do in a chemical analysis is to carefully apply a technique that experience tells us is reliable. Repetition of one method of measurement several times tells us the precision (reproducibility) of the measurement. If the results of measuring the same quantity by different methods agree with one another, then we become confident that the results are accurate, which means they are near the true value. 

There are a number of general requirements for a test method it must have adequate precision, reproducibility etc. There are, however, particular attributes related to the purpose of testing -... 

What factors can be used to predetermine the quality and utility of a method An analyst must consider the following questions Do I need a proximate analytical method that will determine all the protein, or carbohydrate, or lipid, or nucleic acid in a biological material Or do I need to determine one specific chemical compound among the thousands of compounds found in a food Do I need to determine one or more physical properties of a food How do I obtain a representative sample What size sample should I collect How do I store my samples until analysis What is the precision (reproducibility) and accuracy of the method or what other compounds and conditions could interfere with the analysis How do I determine whether the results are correct, as well as the precision and accuracy of a method How do I know that my standard curves are correct What blanks, controls and internal standards must be used How do I convert instrumental values (such as absorbance) to molar concentrations How many times should I repeat the analysis And how do I report my results with appropriate standard deviation and to the correct number of significant digits Is a rate of change method (i.e., velocity as in enzymatic assays) or a static method (independent of time) needed ... 

The areas which need to be addressed to bring SFE into the routine laboratory are precision/reproducibility and multi-sample analysis. Without development in these directions, competition with conventional methodology does not exist. As demonstrated by applications to Agricultural Products, experiments will be presented which show the feasibility of using SFE as a routine analytical tool in sample preparation. 

The hypnotic state is a psychological construct or, if induction has been successful, an experiential reality to the hypnotized person. It is not defined by external measurements. There are no obvious behavioral manifestations that clearly indicate hypnosis has occurred and no known physiological changes that invariably accompany hypnosis. The hypnotic procedure, on the other had, the words that they hypnotist says aloud, is highly amenable to physical measurement. An investigator can film the hypnotic procedure, tape-record the hypnotist s voice, measure the sound intensity of the hypnotist s voice, and accumulate a variety of precise, reproducible physical... 

Accuracy Range Precision Repeatability Intermediate Precision Reproducibility Precision System Precision Method Specificity Selectivity Linearity... 

As noted in the introduction, a major aim of the current research is the development of "black-box" automated reactors that can produce particles with desired physicochemical properties on demand and without any user intervention. In operation, an ideal reactor would behave in the manner of Figure 12. The user would first specify the required particle properties. The reactor would then evaluate multiple reaction conditions until it eventually identified an appropriate set of reaction conditions that yield particles with the specified properties, and it would then continue to produce particles with exactly these properties until instructed to stop. There are three essential parts to any automated system—(1) physical machinery to perform the process at hand, (2) online detectors for monitoring the output of the process, and (3) decision-making software that repeatedly updates the process parameters until a product with the desired properties is obtained. The effectiveness of the automation procedure is critically dependent on the performance of these three subsystems, each of which must satisfy a number of key criteria the machinery should provide precise reproducible control of the physical process and should carry out the individual process steps as rapidly as possible to enable fast screening the online detectors should provide real-time low-noise information about the end product and the decision-making software should search for the optimal conditions in a way that is both parsimonious in terms of experimental measurements (in order to ensure a fast time-to-solution) and tolerant of noise in the experimental system. 

LC-MS/MS assays typically rely on the use of an internal standard that mimics the performance of the analyte to improve the precision, reproducibility and reliability of the assay. An ideal internal standard candidate is a stable-isotope labeled ( stable labeled ) form of the drug. Because synthesizing stable labeled chemicals can be expensive and time-consuming, it is very common to use a chemically similar structural analog of the analyte(s) as the internal standard, especially during the early phases of drug development. 

No matter whether a new material is radically novel or reminiscent of familiar ones, its exploration requires imagination and an excellent gift of observation, and it is beset by uncertainties Will its odor quality be precisely reproducible in large-scale synthesis or (in the case of novel natural materials) commercial cultivation Will it not turn out to be too expensive to be useful Will it be commercialized at all ... 

This extraction precisely reproduces the same London, Debye, and Keesom interactions, including all relativistic retardation terms that had been effortfully derived in earlier formulations. These interactions are distinguished by whether they involve the interaction of two permanent dipoles of moment //.uipoie, or involve an inducible polarizability aind. A water molecule, for example, has both a permanent dipole moment and inducible polarizability. The contribution of each water molecule to the total dielectric response is a sum of the form of Eqs. (L2.163) and (L2.173) in mks units,... 

Reduced parameters, 66-69 Refractive index (RI) detector, 206-207 Regular solution, 49 Relative retention, 20-21, 22, 77 Repeatability, see Precision Reproducibility, see Precision Resolution, 17-19, 55 Response factors (detector), 104, 125 Response time, 94 Retardation factor, Rf, 71 Retention index of Kovats, 78 Retention ratio, 11, 12, 71 Retention time, 6, 9 Retention volume, 9, 75 adjusted, 10, 75 corrected, 62-63, 75 net, 63, 75 specific, 110 Reverse phase LC, 158 Rohrschneider/McReynolds constants, 137-140... 

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