# Extension:Math/T167569

the example string ${\displaystyle \mathrm {HSO_{4}^{-}} }$ produces a minus which is not in superscript, while it works correctly with numbers before the minus (e.g. 2-) ${\displaystyle \mathrm {SO_{4}^{2-}} }$
you could use ${\displaystyle {\ce {HSO4-}}}$