Determine the solute in the solution, which is either a positive cation or a negative anion. In a solution of carbonic acid, H2CO3 or H+ HCO3-, the solute is carbonate, HCO3-.
Obtain the milliequivalent weight of the solute from a milliequivalent weight table. The milliequivalent weight of HCO3- is 61.016.
Multiply the concentration of the solution in MEQ by its milliequivalent weight to get PPM. If you have a 5.05 MEQ solution of Bicarbonate (HCO3-), perform this calculation as follows:
5.05 x 61.016 = 303.08 PPM HCO3-