We used three protocols to detect the resulting hyperpolarization (Fig. .B). Protocol 1 includes the standard detection of the net magnetization with 90 o hard RF pulse and subsequent registration of the free induction decay (FID). Fourier transform of the FID yields the desired 1 H, C or N NMR spectrum, depending on the spectrometer channel used for registration. To detect the singlet order we first applied the gradient T00 filter to suppress everything except the SO and then converted it into the observable magnetization with S2M pulse sequence (protocol 2). We also tested the possibility of deriving SO from the net magnetization obtained via SABRE (protocol 3).