To avoid errors due to inexperience, validation experiments should be performed by an experienced analyst. And the analyst should also be very well versed in the technique and operation of the tool. Instrument performance specifications are verified using generic chemical standards before an instrument is used to validate a method. Satisfactory results can be obtained for a method only with equipment that works well. Particular attention should be paid to the characteristics of the equipment that are critical to the method. For example, if the detection limit is critical for a specific method, you should check the instrument specifications for background noise and, for some detectors, the response to specific compounds. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original assay Any chemicals such as reagents and reference standards used to determine critical validation parameters should be available in sufficient quantities, accurately identified, sufficiently stable and controlled for exact composition and purity. Any other materials and consumables, such as chromatography columns, must be new and be qualified to meet the column's performance criteria. This ensures that one set of consumables can be used for most experiments. When operators are sufficiently familiar with the technique and equipment, this will allow them to more easily identify and diagnose unexpected problems and perform the entire process more efficiently. If there is little or no information on the performance characteristics of the method, it is recommended to demonstrate the suitability of the method for the intended use in initial experiments. These studies should include approximate precision, working range and detection limits. If preliminary validation data appear inappropriate, the method itself, equipment, analytical technique, or acceptability limits should be modified. Method development and validation is, therefore, an iterative process. For example, in liquid chromatography, selectivity is achieved through selection of the composition of the mobile phase. For quantitative measurements, the resolution factor between two peaks should be 2.5 or greater. If this value is not reached, the composition of the mobile phase requires further optimization. The influence of operational parameters on method performance will be evaluated at this stage if this was not done during method development and optimization. There are no official guidelines on the correct sequence of validation experiments and the optimal sequence will depend on the method itself. For a liquid chromatographic method, the following sequence has proven useful during validation: Selectivity of standards (optimization of separation and detection of standard mixes if selectivity is insufficient) Linearity, limit of quantification, limit of detection, range Repeatability (precision at short term ) of retention times and peak areas Intermediate precision Selectivity with real samples Truth/accuracy at different concentrations Robustness (interlaboratory studies) Experiments that require more time, such as accuracy and robustness, are generally included towards the end . Some of the parameters, listed in points (2) to (6), can be measured in combined experiments. For example, when the precision of peak areas is measured over the entire concentration range, the data can also be used to validate linearity. During validation.