As I see, David has provided a response to your questions. There have been a lot of studies on nitroso indoles which are well known. Many of them are mutagenic. My recommendation will be to look for surrgates with do have nitroso indole group and again, they are not “nitrosamines”. So, dont mix them up and provide separate analysis. Like the nitroso carbamates and nitroso guanidines, they do not need metabolic activation to show their mutagenicity in Ames. Look at this paper, which may give you some idea on nitroso indoles In-vitro testing and the carcinogenic potential of several nitrosated indole compounds - PubMed