Figure 1.

(a) The ¹H NMR spectrum of albumin (black line) compared to a real urine sample containing the same amount of albumin (∼7 mg/mL). (b) Eighty-five urine ¹H NMR profiles from COVID-19 patients, focusing on the backbone −NH (left panel) and parts of methyl proteinic protons (right panel), showcasing the spectral baseline effect from the presence of proteinuria. (c) SMolESY application on the ¹H NMR spectrum of albumin (∼7 mg/mL) and a real urine sample with the same amount of albumin. In both cases SMolESY succeeds in broad signals suppression as well as baseline homogenization, allowing the enhancement of sharp signals from small molecules (i.e., metabolites).