Over time, several innovations have been applied to expand the usage of 31P. Like in 13C and 15N labeling of specific biological compounds, incorporation of 31P can also be used. In order to achieve that, 2-chloro-4,4,5,5-tetramethyldioxaphospholane (CTMDP) can be used for tagging lipids containing hydroxyl, aldehyde, and carboxyl groups that can later be detected with better resolution [121]. Another fairly recent method enables toxicological screening of 31P in living cells for several hours without affecting cell viability [122]. This specific method can be used to observe the changes in energy metabolism in real-time while enabling the evaluation of the effects of administered drugs.