Fig. 1

The Hadamard-DQF-LMO pulse sequence. The white rectangle represents the water suppression (WS) presaturation module, while the composite waveforms p1 and p2 correspond to the polychromatic 180° transition pulse and Hadamard-encoded polychromatic 180° pulse, respectively. The dashed and solid black rectangles denote non-selective 180° and 90° pulses, respectively. The rectangles G1 and G2 indicate the dephasing gradient fields with an intensity ratio of 1：2

Fig. 2

(a) The encoding procedure of the order-N Hadamard-DQF-LMO spectrum; (b) The acquisition spectra of the order-4 Hadamard-DQF-LMO; (c) Resulting LMO spectra after Hadamard decoding of (b). The spectra are shown in absolute mode

Fig. 3

1D 1H NMR spectrum of orange juice (Sample 1), with chemical structures of the target analytes (sucrose, α-glucose and β-glucose) shown above the spectrum

Fig. 4

1D LMO spectra of the orange-juice (absolute value display) acquired with (a) the DQF-LMO sequence and (b) the Hadamard-DQF-LMO sequence

Table 1

SNR comparison between DQF-LMO and Hadamard-DQF-LMO for orange-juice

Fig. 5

1D 1H NMR spectrum of mixed amino acids (Sample 2), with chemical structures of the target analytes (asparagine, glutamic acid, glutamine and valine) shown above the spectrum

Fig. 6

1D LMO spectra of mixed amino acids acquired with (a) the DQF-LMO sequence and (b) the Hadamard-DQF-LMO sequence

Table 2

SNR comparison between DQF-LMO and Hadamard-DQF-LMO for mixed amino acids