Method accuracy demonstration

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 linearity of the method is demonstrated using 3-5 concentration levels. For APIs, the correlation coefficient should be greater than 0.999. The range is derived from linearity, precision, and accuracy studies and should be established based on the intended application of the method. 

Range is not a parameter that can be measured independently, but must be inferred from a review of the data collected for accuracy, precision, and linearity. The validation of an assay method may demonstrate linearity from 50% to 150% of the sample concentration. Accuracy and precision data may have only been collected from 70% to 130% of the sample concentration. The range of this particular method would be from 70% to 130% where all three parameters have been evaluated. 

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. 

Experimental Requirements. Solutions of known concentrations are used to determine the linearity. A plot of peak area versus concentration (in percent related substance) is used to demonstrate the linearity. Authentic samples of related substances with known purity are used to prepare these solutions. In most cases, for the linearity of a drug product, spiking the related substance authentic sample into excipients is not necessary, as the matrix effect should be investigated in method accuracy. 

Orlando and Bonato [73] presented a practical and selective HPLC method for the separation and quantification of omeprazole enantiomers in human plasma. Ci8 solid-phase extraction cartridges were used to extract the enantiomers from plasma samples and the chiral separation was carried out on a Chiralpak AD column protected with a CN guard column, using ethanol-hexane (70 30) as the mobile phase, at a flow-rate of 0.5 ml/min. The detection was carried out at 302 nm. The method is linear in the range of 10-1000 ng/ml for each enantiomer, with a quantification limit of 5 ng/ml. Precision and accuracy, demonstrated by within-day and between-day assays, were lower than 10%. 

Sultana et al. [88] developed a reversed-phase HPLC method for the simultaneous determination of omeprazole in Risek capsules. Omeprazole and the internal standard, diazepam, were separated by Shim-pack CLC-ODS (0.4 x 25 cm, 5 m) column. The mobile phase was methanol-water (80 20), pumped isocratically at ambient temperature. Analysis was run at a flow-rate of 1 ml/min at a detection wavelength of 302 nm. The method was specific and sensitive with a detection limit of 3.5 ng/ml at a signal-to-noise ratio of 4 1. The limit of quantification was set at 6.25 ng/ml. The calibration curve was linear over a concentration range of 6.25—1280 ng/ml. Precision and accuracy, demonstrated by within-day, between-day assay, and interoperator assays were lower than 10%. 

The aim of the present work is to perform a detailed theoretical study of the electronic structures of actinyl nitrates. Relativistic effects are remarkable in the electronic structure and chemical bonding of heavy atoms such as actinide elements[6j. In our previous study, we applied the relativistic discrete variational Dirac-Fock-Slater(DV-DFS) method to study of the electronic structure of uranyl nitrate dihydrate[7]. The accuracy of the DV-DFS method was demonstrate by its ability to reproduce the uranyl nitrate dihydrate experimental X-ray photoelectron spectrum. 

Figure 2 demonstrates the effects of adding octane sulfonic acid to the injection solvent for a reverse-phase separation of pyridinium and deoxypyri-dinium, components of collagen, in rat urine. These polyamine containing compounds are protonated and poorly retained under the usual acidic or neutral mobile-phase conditions. The sample preparation method is simple dilution and does not afford the removal of salts from the sample. Therefore if the analytes were inadequately retained the sensitivity, as well as the method accuracy, would suffer. As the concentration of octane sulfonic acid is increased to 50 mM (Fig. 2a), both the retention time and the peak response for the analytes improve significantly. Litde improvement is obtained at higher concentrations of octane sulfonic acid and retention is not strongly dependent on the injection volume (Fig. 2b). To protect the ion source from the fouling effects of octane sulfonic acid in the injection solvent, a timed divert valve was inserted before the ion source to shunt the excess ion pair reagents to waste during the first few minutes of each injection.

Range is defined by the interval where the method has demonstrated acceptable accuracy, precision, and linearity. 

Once a new analytical method has been developed, it must be optimized and standardized to meet the purposes for which it was developed. Validation studies confirm that a new assay has met its required performance specifications, and must be done before the analytical procedure can become a routine laboratory protocol. There are multiple approaches to validating analytical methods. The most common is to compare results from the new method with results obtained using an established, or reference, assay. Alternatively, standard reference materials (e.g. standards certified by NIST) can be analyzed by the new method to demonstrate its accuracy. When available, authentic specimens should be tested and compared against a previously validated protocol. 

For complexes with relatively simple electronic structures (e.g. d1 and d9 species), DFT Xa methods have demonstrated useful accuracy for both d-d and CT features, especially when Slater s transition state formalism [15] is used. The d-d and CT transition energies of chlorocuprates (II) have been well studied [113-115] and the observed transition energies can be reproduced to about 1000 cm "1 or better. MSXa calculations [114] also predict relative intensities in reasonable agreement with experiment. 

Acetyl and Feruloyl Esters in Pectin. A colorimetric method for determining degrees of acetylation in pectins from various sources ( ), has been shown to be rapid and quite sensitive. Hydroxy-lamine is reactive toward both the methyl and acetyl esters in pectin, and ferric ion complexes with the resulting hydroxamic acids are red. The pectin complex is insoluble and removed by filtration the intensity at 520nm in the soluble fraction, consisting of the ferric complex with acetohydroxamic acid, is a measure of acetyl content. The accuracy of the method was demonstrated in determinations of 0-acetyl levels in standard per-ace-tylated polysaccharides. Another method ( ) involves alkaline hydrolysis of the acetyl groups from pectin, followed by distillation of acetic acid and its titration with standard base. 

Method accuracy should be demonstrated through regular participation in suitable proficiency testing programs (when available) and use of certified reference materials in calibration (when available). 

The analytical method should be complemented with information on accuracy demonstrated for instance by ... 

Methods validation would be critically reviewed for completeness, accuracy and reliability. If an alternative to a compendial method is used, this in-house method must be compared to the compendial method to demonstrate it is equivalent or superior to the official procedure. Appropriate pharmacopoeial guidelines for methods validation should be followed. 

Rclcreiicc Method. A standard method with demonstrated high (or good) precision and frequently high (or good) accuracy. 

Mixed estimators are avoided in the RQMC approach discussed earlier. Recent developments increase RQMC efficiency in studies of large systems [76], Direct assessment of the quality of electron distributions in atoms and molecules showed that the highest accuracy among a variety of QMC methods is achieved by NC-RQMC algorithm [105]. The AFMC method has demonstrated excellent performance in traditionally challenging description of stretched bonds and a related issue of spin-contamination [106],... 

PARSIM optionally provides the method of Finite Differences (FD) for space discretization. An advantage of this method is the lower bandwidth of the Jacobian matrix. Nevertheless, much more node points are needed to achieve the same accuracy compared to the OCFE method as demonstrated below. The method of global Orthogonal Collocation (OC) is provided additionally by PARSIM but should be used only for systems without steep gradients. 

Validation is the process and documentation of the specific laboratory investigations that demonstrate an analytical method is suitable and reliable for its intended appUcations [31]. A validated bioanalytical method must demonstrate accuracy, precision, selectivity, sensitivity, reproducibility, and stability in order to support GLP toxicology studies and clinical trials. Below are the principles and acceptance criteria in each area. 

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