Precision limits

This property should also be within precise limits. In fact, a too-viscous fuel increases pressure drop in the pump and injectors which then tends to diminish the injection pressure and the degree of atomization as well as affecting the process of combustion. Inversely, insufficient viscosity can cause seizing of the Injection pump. 

Method Transfer. Method transfer involves the implementation of a method developed at another laboratory. Typically the method is prepared in an analytical R D department and then transferred to quahty control at the plant. Method transfer demonstrates that the test method, as mn at the plant, provides results equivalent to that reported in R D. A vaUdated method containing documentation eases the transfer process by providing the recipient lab with detailed method instmctions, accuracy and precision, limits of detection, quantitation, and linearity. 

The Vene2uelan tar sands are located ia a 50—100-km belt extending east to west for >700 km, immediately north of the Otinoco River. The precise limits of the deposit are not well defined because exploration efforts ia the past concentrated on light and medium cmde accumulations. 

With this technology it is now possible to achieve extremely accurate speed control of the order of 0.01 % to 0.001 %. To achieve such high accuracy in speed control, closed-loop feedback control systems and microprocessor-based control logistics can be introduced into the inverter control scheme to sense, monitor and control the variable parameters of the motor to very precise limits. 

It is seen that in order to measure retention volumes with a precision of 0.1%, the temperature control must be +/- 0.04°C. This level of temperature control on a thermostat bath is not difficult to achieve but it is extremely difficult, if not impossible, to return to a specific temperature to within +/- 0.04°C after prior change. To achieve a precision of retention volume measurement of 1%, the temperature control must be +/- 0.4°C. This is far more practical as most column oven temperature can be set to a given temperature to within +/-0.25°C. Although the data was obtained for three specific solutes, the results can be taken as reasonably representative for all solutes and phase systems. In most practical analyses, the precision limits of retention volume measurement will be about 1% but this will not include the reproducibility of the flow rate given by the pump. As... 

The precision limit P. The interval about a nominal result (single or average) is the region, with 95% confidence, within which the mean of many such results would fall, if the experiment were repeated under the same conditions using the same equipment. Thus, the precision limit is an estimate of the lack of repeatability caused by random errors and unsteadiness. 

Specificity, Accuracy, Precision, Limit of detection, Limit of quantification, Practicability and applicability under normal laboratory conditions, Susceptibility to interference, Stability)... 

Furthermore, the instrumentation of the RoHS Directive has to be considered in this context. The Directive is targeting a clearly structured business sector with very few clear substance bans (or more precisely limits). For the regulated pollutants in turn very unique risk considerations are possible. Without an extension of the instrumentation to a more sophisticated control system, the complex (chemical) process cannot be reproduced in other sectors. 

Enzyme containing Nation membranes prepared according to the proposed protocol have shown high specific activity and stability of immobilized glucose oxidase. As expected, the simplicity of preparation provided high reproducibility. When the same casting solution is used, the maximum deviation in membrane activity is <2%. This, however, is also the precision limit for kinetic investigations. 

The precision limits r and R are given by equations (4.3a) and (4.3b), respectively, where tv>a is the Student /-value for v degrees of freedom and a corresponds to the stated probability, sr is the repeatability standard deviation and Sr is the reproducibility standard deviation calculated from (v + 1) results ... 

The estimation of the overall precision of a methodfrom its unit operations A frequent problem in analysis is the estimation of the overall precision of a method before it has been used or when insufficient data are available to carry out a statistical analysis. In these circumstances the known precision limits for the unit operations of the method (volume measurement, weighing, etc.) may be used to indicate its precision. Table 2.6 gives the normal precision limits for Grade A volumetric equipment. 

Table 2.6 Precision limits for laboratory equipment used in volumetric analysis burettes 0.02 cm3 for each reading...

The determination of accurate and precise limiting conductivities and ion association constants requires care in the design and use of the conductance apparatus, and in the purification and handling of solvents and salts. For this reason attention is given initially here to experimental aspects of conductance measurements. This is followed by a tabulation of selected data, primarily in dipolar apro-tic solvents, and a brief discussion of data taken in one solvent, acetonitrile, which is intended to show the scope of interpretation possible at the present time. 

To validate the suitability of methods, experiments to establish specificity, accuracy, precision, limits of detection, limits of quantitation, linearity, range, and robustness should be conducted. Furthermore, appropriate system suitability criteria should be developed to assure that the method is performing to pre-established criteria at the time of use. 

The majority of authors agree that plasma digoxin levels in adequately digitalized but nontoxic patients are lower than those in whom toxic symptoms are present and prominent, but there is considerable overlap. Moreover, precise limits for therapeutic effectiveness and toxicity are, for reasons already discussed difficult or impossible to define. Few patients derive much benefit from digoxin at plasma levels below 0.7 ng/ml, and toxic symptoms do not become unduly frequent until plasma digoxin levels exceed 2 ng/ml. 

Because of the small number of patients studied in detail, no valid conclusions could be drawn about the precise limits of plasma chlorpromazine concentration for optimum therapeutic effect. Nevertheless, failure to respond to chlorpromazine was shown in one patient to relate to the extremely low plasma concentrations achieved—even by larger than average daily doses of chlorpromazine—whereas in another patient symptoms were aggravated when plasma levels of chlorpromazine were high. 

Calibration procedures shall include specihc directions and limits for accuracy and precision. There shall be provisions for remedial action when accuracy and precision limits are not met. Calibration shall be performed by personnel having the necessary education, training, background, and experience. 

The calibration of instruments, apparatus, gauges, and recording devices at suitable intervals in accordance with an established written program containing specific directions, schedules, limits for accuracy and precision, and provisions for remedial action in the event accuracy and/or precision limits are not met. Instruments, apparatus, gauges, and recording devices not meeting established specifications shall not be used. 

The reliability of a method can be determined by assessing certain method performance criteria including, specificity, accuracy, precision, limit of detection and quantitation, sensitivity, applicability, and practicability as appropriate (13). This very often requires that an extensive collaborative study be undertaken to obtain the necessary data. Methods that have successfully undergone this performance review testing have been considered to be validated for the purpose of the analysis (14). 

The adiabatic Iv obtained with the spectral threshold method and that of the mass spectrometer do agree within these precision limits and also with the values from the Rydberg series.1-3 7 8... 

Acceptability is determined for each parameter by comparison of the standard deviation (s) and the average recovery (X) with the corresponding acceptance criteria for precision and accuracy as published in the method for the analytes of interest. If s and X for all parameters of interest meet the acceptance criteria, the system performance is acceptable and analysis of actual samples may begin. If any individual s exceeds the precision limit, or if any individual X falls outside the range for accuracy, the system performance is unacceptable for that parameter. The analyst must locate and correct the source of the problem and repeat the test for all parameters that failed. 

Electrolytic type sensors Uxt thick film techniques, e.g. capacitor coated in gl bonded on to a ceramic disc mounted on a thermoelectric (Peltier effect) cooler. Control is by a platinum resistance thermometer which adjusts the temperature of the cooler to regain equilibrium after a change in capacitance due to moisture deposit. Range depends on technique. Capable of high precision. Limitations are similar to those for AIjO) sensor. Capable of being direct mounted. Relatively cheap. Suitable for on-line use. 

Specify a precision limit for the amount at the limit of quantitation. Prepare six standard solutions with the amounts in the range from the expected limit of quantitation to 20 times this amount. Inject all samples six times and calculate the standard deviations of the amounts. Plot the standard deviations versus the amounts. Take the specified standard deviation at the corresponding LOQ amount from the plot. 

Plot precision vs. concentration. Concentration at expected precision = limit of quantitation. 

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