Validation and Ongoing Performance Evaluation

The optimization process as described in Chapter 2 is a critical one for the analyst. Successful method optimization means that targeted, defined criteria (e.g., resolution, elution time, sensitivity) have been met through the use of an experimentally determined set of variables (flow rate, mobile phase composition, system temperature, detector settings, column type, etc.). 

However, in many instances, the mere establishment of a separation that meets these criteria is not enough. More critically, and often neglected, omitted, or forgotten, is the fact that the true value of a separation is not that the separation was successful once but that the separation will generate comparable results when the method is run exactly as described by a scientist trained in the field. This involves a three-step process instrument qualification, method development/ validation, and ongoing system performance checks (known as system suitability tests). 

The initial instrument qualification process is detailed and comprehensive and includes both software (computer programs used in data acquisition, analysis, and archiving) and hardware (pumps, detectors, injectors, etc.). Once the instrument is qualified then methods themselves are developed and validated. The development process includes the initial evaluation of the appropriateness of the test, which is often determined by the ability of the method to meet targeted method requirements or mandates (linear range, linearity, accuracy, quantitation limits, resolution, etc.). Once these fundamental requirements are met, the cost effectiveness and overall efficiency are reviewed. Upon acceptance, a developed method then goes through a validation process. 

It should be noted that the method that is derived from the development process is captured in a method document. A method document suggests the general opera- 

A method is distinctly different from a standard operating procedure (SOP). An SOP is the document that details the exact operating procedures that were derived from the method and are oflen laboratory specific. An SOP will define sample size/weight and preparation, diltient and dilution volumes, standard curve concentrations, flow rates, detector/data acquisition settings, etc. In essence, the SOP is the master document used in the quality assurance/control laboratory. 

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Prospective validation, which includes all main validation phase approvals by means of design qualification (DQ), including specification reviews, installation qualification (IQ), operational qualification (OQ), performance qualification (PQ), and ongoing evaluation. 

Abstract Existing software and computer systems in laboratories require retrospective evaluation and validation if their initial validation was not formally documented. The key steps in this process are similar to those for the validation of new software and systems user requirements and system specification, formal qualification, and procedures to ensure ongoing performance during routine operation. 

ICCVAM evaluated the Frog Embryo Teratogenesis Assay— Xenopm (FETAX) as an alternative method for assessing developmental toxicity. In 2000, ICCVAM convened an expert panel and concluded that FETAX was not sufficiently validated or optimized for regulatory applications (31). Research using FETAX has been ongoing to address ICCVAM s recommendations that further standardization of the assay was necessary to improve variability and to expand the number of endpoints assessed to increase the performance of the assay. 

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