Dear all,
Is this acceptable to report the results of below 1 ppm in points(eg. 0.2ppm).
Yes. You can report results below 1 ppm provided the analytical method is sensitive to detect fraction of ppm (Limit of detection and Limit of quantitation).
Are these limits related to potent impurities if yes and if 1 ppm is your limit set as per daily dose then your method should be so sensitive that you are able to set and detect consistent LOQ levels. With respect to reporting you can report these impurities upto 2 to 3 decimal places that is acceptable.