Greeting,

I am assigned to verified O2 limit test method in NF N2 monograph as per USP <1226>. I am wondering to what extent I shall perform the method verification. I think system suitability is a must, how about other parameters, like limit of quantification (LOD), precision, accuracy?

The test method is showed below:

Sample: Nitrogen Sample
Standard: 1.0% Oxygen in nitrogen certified standard

Chromatographic system

Mode: GC
Detector: Thermal conductivity
Column: 2.1-mm × 2.4-m, packed with 80/100 mesh S3 packing
Carrier gas: Helium (99.99%)
Flow rate: 30 mL/min
Column temperature: Thermostatically controlled at 70 degree C

System suitability
Samples: Standard and Sample

System suitability requirements
Resolution: NLT 2.0 between nitrogen and oxygen, Standard
Retention time: The oxygen peak response from the Sample exhibits a retention time corresponding to that from the Standard.

Analysis
Samples: Standard and Sample
Introduce the Samples separately into the gas chromatograph by means of a gas sampling valve.

Acceptance criteria: NMT 1.0% of oxygen when compared to the peak response of the Standard, indicating NLT 99.0%, by volume, of N2

Thanks in advance,

Terry