To understand the peaks in the ZULF spectrum it is useful to consider the Pople notation . The molecules of interest can be modeled as an XA n system, where magnetically equivalent spins A n are equally coupled to a heteronuclear spin X . In the ZULF regime, the Jcoupling interaction is dominant and causes observable transitions at integer and half-integer multiples of the Jcoupling constant. In this work, we studied [ 13 C]sodium formate, [1-13 C] glycine, and [2-13 C] acetate, which correspond to XA , XA 2 , and XA 3 spin systems, respectively. These systems have observable transitions at J XA , 3/2×J XA , and J XA and 2×J XA , respectively . The ZULF spectrum of the hyperpolarized sample HP1 features peaks at 1 J CH = 194.7 Hz for formate and two peaks at 1 J CH = 127.3 Hz and 2× 1 J CH for acetate (see Fig. ).