You have a PhD, don't waste your time on the Mass Spec job unless its just a placeholder. I have run analytical equipment before (ICP MS, GC, FTIR, UV-VIS, and AFM) and in most casaes, depending on the size of the company, if you are a tech you are getting the assignments/samples/run sheets from an MPT/PHD. There were exceptions, like the AFM, but that was because it was a very small company, the equipment and its application (nanotubes) were exceptionally exotic, and I was the only person with the time and understanding to run the research program around it.
For me a mass spec job wouldn't be bad, but I am a bachelored chemist. Having experience running equipment like that is part of my toolbox. For you, running the equipment doens't really matter, its the results that do. Maybe you would implement some better calibration methods and other things, but if its an ISO lab you will spend your day plugging and chugging. And that shit is way below you. Fuck, its below me. That stuff is for lazy assed bachelored scientists who are happy being a monkey who pushes a button and gets a treat.
I swear, if I had a dollar for the amount of half assed procedures I have seen on a piece of analytical equipment...ugh. My first week at my current company I tought myself the GC software and concepts around it and fixed problems that had been monkeyed for almost a decade. They had all these useless fucking methods in there. They were treating every gas as having a non-linear calibration curve and had bought like 10 different cal gas containers to handle the different concentrations.
Now, I have a 4 year degree, and a little motivation and fundamental knowledge, and I was able to completely learn that system and fix it in 2 days. That's how painfully simple these things are. And I doubt mass spec will be much harder. The AFM was different because there was so much image analysis associated with it as well as developing methods for novel materials.
I dunno man, of what you have listed the Mass spec job sounds like the absolute worst one on the list.