As part of our ongoing effort to delineate the biochemical events in muscle physiology, we are interested in correlating direct detection of lactate, a branch product from glycolysis, to establish its potential role in limiting voluntary exercise.  Our approach utilises nuclear properties present in lactate distinguishing it from water and other metabolites.  In the case of water, this preferential detection is made obvious by the limit in detection due to water's overwhelming presence, as exemplified in this typical spectrum of a human muscle:

Can you see the lactate?

Therefore, we make use of the cross-talk between protons in the lactate molecule.  This so-called J-coupling gives rise to multiple [double] quantum coherence between the adjacent protons on the molecule:

Utilising specialised pulse sequences, we can tune into these coherences and map them onto observable single quantum coherences:

As an additional feature of this detection method, we utilise the ability to select lactate frequencies separate from other coupled molecules;  the 2nd to last pulse [here called p/2_sel] is frequency selective allowing discrimination of lactate from e.g. lipid which is dominant in the absence of the water.