Temperature dependence of NMR secondary references for D 2 O and (CD 3 ) 2 SO solutions

Chemical shifts of secondary references for D 2 O and (CD 3 ) 2 SO solutions were measured as a function of temperature. The 1 H and 13 C chemical shifts of dioxane, sodium 4,4‐dimethyl‐4‐silapentanesulphonate, HOD, tetramethylammonium chloride and sodium 3‐(trimethylsilyl)propionate‐ d 4 in D 2 O solution were measured relative to external TMS and the chemical shifts of (CD 3 ) 2 SO and H 2 O were measured in (CD 3 ) 2 SO solution relative to internal TMS. For accurate comparison of chemical shifts it is necessary to take into account the sample temperature and, therefore, the temperature dependences of 1 H and 13 C chemical shifts of a number of secondary references have been determined accurately and fitted to a parabola or straight line, as appropriate.