Hi, @Muzaffar.
Thank you for sharing the information. It’s interesting!! I understand the tentative limit of 153ng/day for Nitroso-Sitagliptin(NTTP) assigned from 1,2,6-Trimethyl–4-nitrosopiperazine was replaced with 37ng/day from 1,2,3,6-Tetrahydro-1-nitrosopyridine(NTHP). And NTHP was also used for the calculation of the Nitrosovarenicline(NNV) limit. As @kpcross explained in the varenicline topic, analogs that have similar reactivity of the nitrosamine functionality are important.
1,2,6-Trimethyl–4-nitrosopiperazine
1,2,3,6-Tetrahydro-1-nitrosopyridine