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发表于 2016-6-16 11:29:58
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USP39-NF34<621>
SYSTEM SUITABILITY
System suitability tests are an integral part of gas and liquid chromatographic methods. These tests are used to verify that the chromatographic system is adequate for the intended analysis.
The tests are based on the concept that the equipment, electronics, analytical operations, and samples analyzed constitute an integral system that can be evaluated as such.
Factors that may affect chromatographic behavior include the following:
Composition, ionic strength, temperature, and apparent pH of the mobile phase
Flow rate, column dimensions, column temperature, and pressure
Stationary phase characteristics, including type of chromatographic support (particle-based or monolithic), particle or macropore size, porosity, and specific surface area
Reverse-phase and other surface modification of the stationary phases, the extent of chemical modification (as expressed by end-capping, carbon loading, etc.)
The resolution, RS, is a function of the number of theoretical plates, N (also referred to as efficiency), the separation factor, α, and the capacity factor, k. [Note—All terms and symbols are defined in the preceding section Definitions and Interpretation of Chromatograms.] For a given stationary phase and mobile phase, N may be specified to ensure that closely eluting compounds are resolved from each other, to establish the general resolving power of the system, and to ensure that internal standards are resolved from the drug. This is a less reliable means to ensure resolution than is direct measurement. Column efficiency is, in part, a reflection of peak sharpness, which is important for the detection of trace components.
Replicate injections of a standard preparation or other standard solutions are compared to ascertain whether requirements for precision are met. Unless otherwise specified in the individual monograph, data from five replicate injections of the analyte are used to calculate the relative standard deviation, %RSD, if the requirement is 2.0% or less; data from six replicate injections are used if the relative standard deviation requirement is more than 2.0%.
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