VOC detection

Hello,

I have searched for long days and I find a few Figures of VOC detection curves... If I undersatand well if I get a value around 180-200 response with TGS 2602sensor I have found a VOC object ?!?!?! Or can I do anything else (e.g. another calibration...) ? // TGS2602,TGS2620 are made for VOC sense!! //

Figure 01

With the Figure 02 must I do anything?

Figure 02

Thanks for the answers ;)