To avoid errors due to inexperience, validation experiments should be performed by an experienced analyst. In addition, the analyst must be very familiar with the technique and operation of the instrument. Instrument performance specifications are verified using generic chemical standards before an instrument is used to validate a method. Satisfactory results can only be obtained for a method with efficient equipment. Particular attention should be given to equipment characteristics that are critical to the method. For example, if the detection limit is critical for a specific method, the instrument specifications for baseline noise and, for some detectors, response to specified compounds should be verified. Say no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”? Get an original essay Any chemicals such as reagents and reference standards used to determine critical validation parameters must be available in sufficient quantities, accurately identified, sufficiently stable and verified for exact composition and purity. All other materials and consumables, for example chromatographic columns, must be new and qualified to meet the column performance criteria. This ensures that a single set of consumables can be used for most experiments. When operators are sufficiently familiar with the technique and equipment, it will allow them to more easily identify and diagnose unforeseen problems and execute the entire process more efficiently. If there is little or no information on the performance characteristics of the method, it is recommended to prove the suitability of the method for its intended use in initial experiments. These studies should include approximate precision, working range and detection limits. If the preliminary validation data appears inadequate, the method itself, the equipment, the analytical technique, or the acceptance limits should be modified. Method development and validation is therefore an iterative process. For example, in liquid chromatography, selectivity is achieved through the 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 achieved, the composition of the mobile phase requires further optimization. The influence of the operating parameters on the performance of the method will be evaluated at this stage if this was not done during the development and optimization of the method. 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 chromatography method, the following sequence has proven useful during validation: Selectivity of standards (optimization of separation and detection of standard mixtures if selectivity is insufficient) Linearity, limit of quantification, limit of detection , range Repeatability (short-term precision) of retention times and peak areas Intermediate precision Selectivity with real samples Accuracy/precision at different concentrations Robustness (interlaboratory studies) The longest experiments, such as precision and robustness, are usually included towards the end. Some of the parameters, listed under (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 the.