3.6.8. Robustness and Stability

Robustness is an indicator of method tolerability when small variations occur in method parameters to ensure the reliability of the method during routine analysis. In this study, the robustness of the method was determined as the suitability of the system to permit changes in transfer temperature and headspace equilibration time. The precision values of the peak response and retention time for four nitrosamines were determined after slight variation in the method parameters. The %CV of the peak area and retention time should be ≤11 and 2, respectively, whereas the tailing factor of each injection should be lower than 2. Moreover, the influence of the flow rate on the resolution between ¹⁵N-DMF and NDMA was studied. The resolution should be >2. In addition, the stability of the sample solutions was investigated. To confirm the good stability of the sample solution, the percent deviation of the analyte concentration between the initial time point (0 h) and the storage time of 6, 12, or 24 h should not be greater than 10%.