We were able to extract an approximate 31 P solution NMR T 2 relaxation for the splitting time point of 6.14 ms and a T 1 of 7.4 (monoexponential fit) 95% 7.94 s and 5% 0.47 s (biexponential fit) with an error of 0.5 s. We arrested the solution at three hours when there was explicit NMR splitting that had been stable across a formation time of a few hours, by adding AMUPol already dissolved in D 2 O, then glycerol-d8, and lastly plunging the sample in liquid nitrogen. The resulting final vitrified sample consisted of 0.147 mM phosphate and 0.072 mM calcium total. A 1D ssNMR spectrum was acquired of this sample. Four distinct 31 P NMR chemical shifts appeared (Figure ). We completed even and odd spin counting experiments on this sample and analyzed these chemical shift environments (Figure ), where the middle peak two environments were combined into one due to their very closely overlapping chemical shifts. We extracted even ordered experimental minimum MQCOs of (dark blue for traditional Fourier transform method in Figure ) for the odd coherence orders. The left peak exhibits a very small MQCO of 2 for all excitation times (Figure ) and has significant overlap with the CS of monophosphate control sample. The right peak environment was difficult to distinguish from noise during analysis and as evidenced by the even and odd SC profile showing no discernible cosinusoidal shape or meaningful Fourier transform. This might be due to the presence of a significant population of isolated phosphates present, not enough scans acquired, or due to a different optimal excitation time of 3.2 ms / mixing time of 6.4 ms (Figure , MQCO of 2 is clearly extracted with conventional Fourier transform method). This middle merged peak environment has a T 2 relaxation of 14.17 ms (which is more than the experimental mixing time of 9.6 ms) and exhibits a lower CSA than most environments for ATP in DNP juice, and yielded an extracted MQCO of a minimum of 6. Considering the MQ-SC results of model systems and fully formed HAp crystals and ACP solids, the observation of such a high and distinct MQCO of 6 is unexpected and significant. The results of different analysis methods are consistent in yielding a MQCO of 6; the incorporation of additional cosine frequencies 7 and 8 did not exceed their respective error bars (Figure ). The species giving rise to MQCO of 6 could be small ACP solids or likely a calcium phosphate prenucleation cluster (or both due to the presence of two peaks), potentially even including the Posner cluster which is proposed to be made of six phosphate atoms . These exploratory results can be expanded upon with further structural analysis in the future.