Multiple acquisitions via sequential transfer of orphan spin polarization (MAeSTOSO): How far can we push residual spin polarization in solid-state NMR?

Conventional multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) experiments detect the signal arising from the decay of a single coherence transfer pathway (FID), resulting in one spectrum per acquisition time. Recently, we introduced two new strategies, namely DUMAS ((DU) under bar al acquisition (M) under bar agic (A) under bar ngle (S) under bar pinning) and MEIOSIS ((M) under bar ultiple (E) under bar xperiments via (O) under bar rphan (S) under bar pin operator (S) under bar), that enable the simultaneous acquisitions of multidimensional ssNMR experiments using multiple coherence transfer pathways. Here, we combined the main elements of DUMAS and MEIOSIS to harness both orphan spin operators and residual polarization and increase the number of simultaneous acquisitions. We show that it is possible to acquire up to eight two-dimensional experiments using four acquisition periods per each scan. This new suite of pulse sequences, called MAeSTOSO for (M) under bar ultiple (A) under bar cquisitions via (S) under bar equential Transfer of Orphan Spin p (O) under bar larization, relies on residual polarization of both C-13 and N-15 pathways and combines low-and high-sensitivity experiments into a single pulse sequence using one receiver and commercial ssNMR probes. The acquisition of multiple experiments does not affect the sensitivity of the main experiment; rather it recovers the lost coherences that are discarded, resulting in a significant gain in experimental time. Both merits and limitations of this approach are discussed. (C) 2016 Elsevier Inc. All rights reserved.