If you are using VOC sampler with 3m 3500 badge for Benzene and Benzo(a)pyrene sampling, there is NAAQS CPCB (India) standard limit for that with sampling procedure. You can refer to the following link as per the Indian standard
Hi, I wrote a paper on the development of dynamic standards of VOCs, depending on the vapor pressure of the substances you want to calibrate, you could easily adapt it. The article is here: Article Development of a primary diffusion source of organic vapors ...