Accuracy recovery testing

Referee Laboratories and Spike Recovery Testing. Outside laboratories, with demonstrated performance records, can be used to evaluate the suitability of a candidate method when none of the other accuracy testing options is feasible. However, This technique provides a very weak form of accuracy assessment. Indeed, it provides a comparability check, not an accuracy measure. Similarly, spike recovery tests provide only weak evidence of method accuracy. Quantitative spike recovery only indicates that the added form of the analyte was recovered. If the added form responds differently toward sample preparation or detection the utility of spike recovery testing remains doubtful. 

Accuracy Recovery Linearity Spiked placebo test Intercept of a linearity plot... 

Accuracy. In the quantitative method that is used to measure the heavy metal quantity in the drug substance, the accuracy is usually represented by the recovery rate obtained from a spiked recovery test where lead is added to the samples. Since the heavy metals limit test specified in monograph specifications is a test where the intensity of coloring of the samples with sodium sulfide is compared with that of the control solution, it is necessary to confirm that heavy metal components can be detected fully in the process of test solution preparation. The Heavy Metals Limit Test in JP specifies four preparation methods for the test solutions. An appropriate method will be selected and used for further testing. The test method that gives the best recovery rate is to be adopted. The procedure is as follows ... 

The accuracy of the methods described above for the analysis of biological and food samples has been checked by dilferent approaches. These include recovery test and standard addition, use of independent analytical methods of proven validity, and verification of the method by means of CRMs, the latter two approaches being the most applied. In the specibc case of biological and food samples, a great variety of CRMs, such as those produced by NIST, BCR, NRC, and IAEA, are available. The reliability of the techniques mentioned in this survey has been mainly checked against these CRMs. There is much evidence in the literature that the capabilities of the solubilization sampling technique compare favorably with those of other techniques. 

The accuracy was tested by analyzing particulate-loaded filters, spiked with a known amount of tin before the digestion. The average recovery was 98.0 8.5% (n = 4). 

A procedure for the determination of molybdenum in serum, red blood cells, and urine is described. The low concentration of molybdenum in most unexposed individuals requires the sensitivity obtained using atomic absorption spectrophotometry and electrothermal atomization. Spike recovery tests indicate that low temperature ashing is required for accuracy. Severe matrix interferences preclude wet ashing or high-temperature ashing as sample pretreatments. Using the method described, it is possible to distinguish between industrially exposed and unexposed individuals. 

An RSD of more than 1.5% for a recovery test cannot be permitted. RSD values assure both the accuracy and the reliability of the analytical information. 

The residue was dissolved in toluene/acetnitrile (1 3) and loaded on an ENVI-Carb/NH2 column, and then eluted with 30ml toluene/acetnitrile (1 3). The eluate was evaporated to dryness and the residue was dissolved in 1ml acetonitrile. To verify the accuracy and precision of the method we conducted recovery tests in triplicates at 0.2mg g as the spiking level. 

Multicommutation also allows implementation of procedures for assessment of accuracy. For example, the same analyte can be determined by two different methods with the same flow network. In this way, a multicommutated flow manifold was proposed for chloride determination in natural waters with different sample matrices based on the spectrophotometric procedure using mercury(II) thiocyanate and the turbidimetric method using silver nitrate [19]. Moreover, in-line addition/recovery tests were implemented for every assayed sample in order to detect matrix effects. 

Dilution of concentration acceptable if calibration, accuracy and precision remain so. Data generated during tests of other characteristics may provide this requirement Where the method does not permit recovery to be estimated, accuracy and precision are those of calibration Storage times should reflect those likely to be required... 

Another way to verify the accuracy of a method (I) under validation is the analysis of a given set of test samples with graduated analyte concentrations by both methods, (I), and an independent one (II), which is known to be accurate. The special recovery function in this case is given by Eq. (6.47b). 

The accuracy of an analytical method is given by the extent by which the value obtained deviates from the true value. One estimation of the accuracy of a method entails analyzing a sample with known concentration and then comparing the results between the measured and the true value. The second approach is to compare test results obtained from the new method to the results obtained from an existing method known to be accurate. Other approaches are based on determinations of the per cent recovery of known analyte spiked into blank matrices or products (i.e., the standard addition method). For samples spiked into blank matrices, it is recommended to prepare the sample at five different concentration levels, ranging over 80-120%, or 75-125%, of the target concentration. These preparations used for accuracy studies usually called synthetic mixtures or laboratory-made preparations . 

The acceptance criterion for recovery data is 98-102% or 95-105% for drug preparations. In biological samples, the recovery should be 10%, and the range of the investigated concentrations is 20% of the target concentrations. For trace level analysis, the acceptance criteria are 70-120% (for below 1 ppm), 80-120% (for above 100 ppb), and 60-100% (for below 100 ppb) [2]. For impurities, the acceptance criteria are 20% (for impurity levels <0.5%) and 10% (for impurity levels >0.5%) [30], The AOAC (cited in Ref. [11]) described the recovery acceptance criteria at different concentrations, as detailed in Table 2. A statistically valid test, such as a /-test, the Doerffel-test, or the Wilcoxon-test, can be used to prove whether there is no significant difference between the result of accuracy study with the true value [29],... 

Precision and accuracy Quantitative analysis by NMR is very precise with relative standard deviations for independent measurements usually much lower than 5%. The largest errors in NMR measurements are likely due to sample preparation, not the NMR method itself. If a good set of standards is available and all NMR measurements for the test and standard samples are performed under the same acquisition conditions, the quantitative results can be readily reproduced on different instruments operated by different analysts at different times. Therefore, good intermediate precision can also be achieved. An accurate quantitative NMR assay will require accurately prepared standards. The accuracy of an NMR assay can be assessed, for example, by measuring an independently prepared standard or an accurate reference sample with the assay. In many cases, a spike recovery experiment can also be used to demonstrate the accuracy of an NMR assay. 

The accuracy of an analysis can be determined by several procedures. One common method is to analyze a known sample, such as a standard solution or a quality control check standard solution that may be available commercially, or a laboratory-prepared standard solution made from a neat compound, and to compare the test results with the true values (values expected theoretically). Such samples must be subjected to all analytical steps, including sample extraction, digestion, or concentration, similar to regular samples. Alternatively, accuracy may be estimated from the recovery of a known standard solution spiked or added into the sample in which a known amount of the same substance that is to be tested is added to an aliquot of the sample, usually as a solution, prior to the analysis. The concentration of the analyte in the spiked solution of the sample is then measured. The percent spike recovery is then calculated. A correction for the bias in the analytical procedure can then be made, based on the percent spike recovery. However, in most routine analysis such bias correction is not required. Percent spike recovery may then be calculated as follows ... 

Accuracy of reference weighing 98.0-102.0% recovery API 98.0-102.0% recovery API 75-125% recovery API Tested by analysis of a second reference solution... 

The accuracy of a method is defined as the closeness of the value obtained to known or accepted values. Accuracy can be determined in a number of ways, depending on the nature of the CZE method and availability of orthogonal techniques to compare results. If practical, spike recovery studies (i.e., testing to determine whether recovery matches the amount of a known analyte or impurity spiked) are good alternatives to orthogonal assay comparisons. ICH guidelines also allow method accuracy to be inferred, once specificity, linearity, and precision are established. 

Bend, Twist and Touch (Fig. 36) was a physical task that showed changes similar to those observed for cognitive tasks. Masking Speed (Fig. 37) likewise reflected similar effects. As with many tests, some improvement as a result of practice was evident at the time of recovery. Rifle accuracy (Fig. 38) was greatly diminished in the medium and high dose groups but only briefly at the lowest (MEDjo) dose. 

Determination of Accuracy and Precision of the Analytical Procedure. The desorption efficiency was determined for each method at widely separated analyte quantities to establish the average recovery to be expected. The spiking and analysis procedures for these tests were similar to those described earlier for the preliminary desorption efficiency tests. For HCCP and... 

The ideal validated method would be the one that has progressed fully through a collaborative study in accordance with international protocols for the design, conduct, and interpretation of method performance studies. A typical study of a determinative method conducted in accordance with the internationally harmonized International Organization for Standardization (ISO)/International Union for Pure and Applied Chemistry (IUPAC)/AOAC International (AOAC) protocol would require a minimum of up to five test materials including blind replicates or split-level samples to assess within-laboratory repeatability parameters, and eight participating laboratories (15). Included with the intended use should be recommended performance criteria for accuracy, precision and recovery. 

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. 

In its original form, the test is a trifle crude but more modem versions have been developed14. At the time of writing, a revision of ISO 2921 is at an advanced stage which decreases the tolerance on the measure of recovery. This will, in principle, improve the accuracy of the method, although the... 

Records for documentation of the mixing procedure used to achieve homogeneity of the test substance in the carrier must be available for audit. Prior to the analysis of the study samples, all analytical procedures must be validated in terms of recovery, reproducibility, sensitivity, freedom from interference, and accuracy. 

---