Validation method, procedures

Initially, robustness testing was performed to identify potentially important factors, which could affect the results of an interlaboratory study.Therefore, the robustness test was executed at the end of the method validation procedure, just before the interlaboratory study. Flowever, a method found to be non-robust should be redeveloped and revalidated, leading to a waste of time and money. For these economical reasons, nowadays, method robusmess is verified at an earlier stage in the lifetime of the method, i.e., at the end of method development or at the beginning of the validation procedure. ... 

The method validation procedure should always be documented in order to give evidence of method performance. Proper documentation has an influence on the consistency and subsequent reproducibility, which, at the final stage affect the uncertainty contribution. The information in the validation documents should be clear and easily understood by everyone who uses the method. 

An example of the minimum requirement for potency assay of the drug substance and drug product is tabulated in Table 4. Note that the postponement of intermediate precision is aligned with previous discussion that the use of early phase analytical method resides mainly in one laboratory and is used only by a very limited number of analysts. Each individual company s phased method validation procedures and processes will vary, but the overall philosophy is the same. The extent of and expectations from early phase method validation are lower than the requirements in the later stages of development. The validation exercise becomes larger and more detailed and collects a larger body of data to ensure that the method is robust and appropriate for use at the commercial site. 

Outsourcing the development, validation, and performance of analytical methods in recent years has become a popular means to facilitate movement of product through the development process. A recent industry survey reported that the vast majority (86%) of the companies responding say they outsource analytical methods development to contract laboratories. Twenty-five percent of the responding firms indicated that they often or always contract out stability testing on development compounds [37]. There are important criteria to follow in working with contract laboratories to ensure that their methods validation procedures yield results that are consistent with those of the client company [38]. This topic will be discussed later in this chapter. 

Comparison of measurement uncertainty and method validation procedures... 

Specificity, or selectivity as recommended by lUPAC, is the factor in the validation process that is most often discussed. Selective methods are required in a product release specification, which means that a chromatographic procedure often has to be carried out but sometimes a simple UV method is sufficiently selective and thus free from interferences. Here cost-effectiveness should be the guide and analysts should therefore use their scientific arguments to justify using the simpler method. Validation procedures are equally important in the documentation of bioanalytical methods. 

Detailed evaluation of test method validation procedures containing all of the recommendations and precautions to be taken into consideration when the TLC method is being routinely used some recommendations should be given as to when and why revalidation might be necessary. 

There is an obvious order to these four facets of analytical methodology. Ideally, a protocol uses a previously validated procedure. Before developing and validating a procedure, a method of analysis must be selected. This requires, in turn, an initial screening of available techniques to determine those that have the potential for monitoring the analyte. We begin by considering a useful way to classify analytical techniques. 

According to Phannacopoeia, methods of dmg quality control must be validated. But now there no justified acceptability criteria and standai dized validation procedures. It presents problems for analysts during method development. 

For standardization of validation procedure we suggested normalized coordinate system (NCS) X. = 100-C/C", Y. = 100-A/A", where C is a concentration, A - analytical response (absorbance, peak ai ea etc.), index st indicates reference solution, i - number of solution. In this coordinate system recuperation coefficient (findings in per cent to entry) is found as Z = IQQ-Y/X. As a result, coordinates of all methods ai e in the unified... 

Important part of validation procedure is prognosis (on basis of Phai macopoeial requirements and results of inter-laboratory trials) of sample preparation, final analytical operation and total uncertainties. It enables to forecast method uncertainty in control laboratories. 

Developed standai d validation procedure is demonstrated for validation of a spectrophotometric assay of ambroxol hydrochloride tablets. Without any considerable revisions, this approach may be applied to chromatographic methods. Recommendations for validation criteria were included in the State Phai macopoeia of Ukraine. 

Determination of the drug substance is expected to be enantioselective, and this may be achieved by including a chiral assay in the specification or an achiral assay together with appropriate methods of controlling the enantiomeric impurity. For a drug product where racemization does not occur during manufacture or storage, an achiral assay may suffice. If racemization does happen, then a chiral assay should be used or an achiral method combined with a validated procedure to control the presence of the other enantiomer. 

The procedures described so far imply that So = 0, but do not rigorously prove that this is so. The final proof comes from a comparison of Sr for the ideal gas, obtained from the integration of Cp data assuming the Third Law is valid combined with the entropies of transition, with values obtained from a calculation of St for the ideal gas by statistical methods. The procedure, to be described in detail in Chapter 10, starts with the Boltzmann equation... 

The accuracy of a method can only be determined if the true answer is known and, of course, for the majority of analyses it is not. The accuracy of a method is determined during its validation procedure by the analysis of samples containing known amounts of analyte. In order to ensure that the method accuracy is maintained during routine use, samples containing known amounts of analyte are analysed among the unknowns as part of a quality control regime [12, 13]. 

Demonstrating that an analytical procedure performs as intended is a GMP concem. 9.35-37,128-132 Jo this end, the employed equipment and the design of the method should be such that the intended goals can be met. The method validation delivers the formal proof that the outcome meets the expectations. 

The inherent reproducibility or imprecision of the method will have been determined as part of the validation procedure. This information can then be applied to the internal quality control programme which is designed to identify the intrusion of a bias (inaccuracy) and/or an alteration in the reproducibility of the assay. Programs for Internal quality control are most extensively developed for clinical laboratories because of the availability of suitable RMs in large batches and at an affordable cost although some level of IQC is appropriate to aU work carried out at a continuing basis see Section 6.2. 

A pharmacopoeial reference substance is intended for the determination of the main component of a substance or for the active ingredient of a pharmaceutical formulation which is usually present at a high proportion of the total. The reference substance is to be used as a primary standard in a specific method validated as prescribed in the ICH Guideline Validation of Analytical Procedure Methodology" (Technical Guide for the Elaboration of Monographs 1996 ICH Guideline 1997). the reproducibility of which is known. This is taken into account when the limits of acceptance (tolerance) for the substance or product are fixed (Daas and Miller 1997,1998). 

Identification of sources of analytical bias in method development and method validation is another very important application of reference materials in geochemical laboratories. USGS applied simplex optimization in establishing the best measurement conditions when the ICP-AES method was introduced as a substitute for AAS in the rapid rock procedure for major oxide determinations (Leary et al. 1982). The optimized measurement parameters were then validated by analyzing a number of USGS rock reference samples for which reference values had been established first by classical analyses. Similar optimization of an ICP-AES procedure for a number of trace elements was validated by the analysis of U S G S manganese nodule P-i (Montaser et al. 1984). 

Second, the newly developed and collaboratively evaluated method may need to be compared to another validated procedure if available, which requires an additional and different data set. 

Finally, it is important to define the lowest level of method validation (LLMV). The LLMV is defined as the lowest concentration level expressed in terms of amount of analyte in the matrix, at which the method (extraction/analysis procedure) was validated or proven to be capable of reliably quantifying. 

In the second phase, analysts in participating laboratories prepare and analyze a minimum of two conttol samples and two samples fortified at the proposed tolerance concenttation. This phase allows analysts to become familiar with the method before the analysis of samples that will be part of the method validation. Results from the second phase should demonsuate that the control samples are without interference and that the analysts in the participating laboratories can achieve acceptable recovery of analyte from the samples. It is not uncommon for an analyst to have to repeat the second phase several times before adequate results are obtained. Failure at this phase of the trial can cause a method to fail the Uial. Often the problems are related to a poorly written SOP that does not adequately describe the procedure. 

In this article, an analytical method is defined as series of procedures from receipt of a sample to final determination of the residue. Validation is the process of verifying that a method is fit for purpose. Typically, validation follows completion of the development of a method. Validated analytical data are essential for monitoring of pesticide residues and control of legal residue limits. Analysts must provide information to demonstrate that a method intended for these purposes is capable of providing adequate specificity, accuracy and precision, at relevant analyte concentrations and in all matrices analyzed. 

In summary, the CSL guidelines can be simply applied in each laboratory and contain very clear instructions. The validated procedures do not focus on the central analytical part only. Important secondary aspects of the whole procedure (sample processing, analyte stability, extraction efficiency) are also considered. For each parameter which is determined, different criteria for the evaluation of quantitative, semi-quantitative and screening methods are given. Here, it should be noted that compared with other guidelines the requirement for the precision of quantitative methods is very stringent (RSD < 10%). 

For the Nordic countries, i.e., Denmark, Finland, Iceland, Norway and Sweden, the validation procedures and acceptance criteria for analytical methods are specified in the Procedure No. 4 of the Nordic Committee on Food Analysis [Nordisk Methodik... 

To reduce the effort, another validation procedure is used for extension of the German multi-residue method to a new analyte. Actually, more than 200 pesticides can be analyzed officially with this method, which is the up-to-date version of the better known method DFG SI9. A typical validation is performed by at least three laboratories, which conduct fortification experiments at the same three levels with at least four representative matrices. These representative matrices are commodities with high water content (e.g., tomato), fruits with high acid content (e.g., lemon), dry crops (e.g., cereals) and commodities with high fat content (e.g., avocado). 

Any validation and verification work performed must always be documented in such a way that the results can be checked and the scope of a method is clear. International standards, e.g., ISO 17025, contain separate sections regarding documentation, which should be observed. The NMKL procedure on method validation states that It is of particular importance that the report includes all raw data from the experimental work, or references to where such data can be found . In some circumstances this complete documentation is impractical. Even where it is practical, it is usually impossible to publish these results together with the methods. 

Confirmatory methods must be sufficiently robust to accurately verity the structure of the analyte. For the US FDA, the validation procedure for confirmatory methods is currently defined by Sphon. Validation criteria include reproducible chromatographic separation, ions chosen to be characteristic of the molecule. 

In 1994, only 15% of EPA method validations (tolerance method validation and environmental chemistry method validations) that involved GC were carried out using GC/MS. In 2002, this number is reversed in that 85% of the GC methods that were validated by both programs used GC/MS. Many of the compounds investigated in these method trials were polar compounds, and hence these compounds required derivatization in order to be amenable to GC. One common methylating agent is (trimethylsilyl)diazomethane, which is used, for example, to methylate the sulfonamide flumetsulam. As opposed to HPLC/MS, where derivatization is often not necessary, the GC/MS procedure involves an extra step to methylate this compound, under dry conditions, prior to determination by GC/MS. 

To show that the method is consistent, it is best to conduct the method validation over two or three sets with different fortification levels carried out in each set. Fortify the leaf disk sample, dislodge, then add the extraction solvent and perform the extraction procedure. 

Method validation, on the other hand, is normally considered part of the study in which the method will subsequently be used or consists of a separate defined study unto itself as such, it is normally required to be accomplished under GLP purview. There is, however, some confusion in some circles as to exactly what is meant by analytical method validation. Some chemists describe it as adaptation of one method from one type of matrix for use with another using basically the same or similar analytical approach. Others take a more strict interpretation and define validation as simply demonstration of the ability to achieve satisfactory results using a published procedure in one s own laboratory setting. Often, validation incorporates both interpretations. 

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