I would like to know if system suitability requirement applies to all chromatographic methods, even when no specific (i.e., explicit) mention is made in the NF monograph. More specifically, I would like to know if the GC
assay for N2 gas (NF) requires meeting the 2% precision criterion for the system suitability.
The following statement is contained in the last paragraph under the procedure section in page 1774 of USP 23 ( Chromatography, Gas Chromatography):
"Many monographs REQUIRE that system suitability requirements be met before samples are analyzed ..." This statement seems to imply that only those monographs explicitly requiring a system would need it. This is in contrast to the statement at the end of the section on HPLC which reads: "Because of normal variations ... a system suitability is required to ensure that a given operating system may be generally applicable." The words MANY is absent, implying that it applies to ALL HPLC methods.
By David on Tuesday, July 18, 2000 - 08:38 pm:
A client of our lab needed to demonstrate that the nitrogen assay as per USP, with Helium as carrier would give equal results as the assay of the same nitrogen sample as per JP using Hydrogen as carrier. They were currently performing JP and wanted to change to USP, and needed some data to support equivalency. I performed a system suitability of 6 injections for USP, and 5 injections as per JP. Both resulted in RSD% under 2.0%. Also performed was a linearity using certified purchased oxygen standards in their respective carrier gases, (0.5%O2,1%O2 and 2%O2).
In both cases, I was able to achieve above 0.995 correlation coefficients for both. As for your question as to should a system be performed for N2 assay, or any other monograph that doesn't specify a system suitability (Methyl Alcohol USP Assay for example). My advice is do perform the system suitability. In my experience exactly interpreting the USP or the FDA is like my dad says, "it's easier to drown a fish". I feel in the event of an audit it's better to have a system suitability perfomed than not have one. It can be done with 3 important points taken into consideration. Purchase a good quality 6 port manual injection valve, keep the pressure set exactly the same each time you load the sample loop and flip the injection lever at the same speed as best you can.
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