The most accurate way to represent the concentration of Product No. 89273 is in molarity due to the multiple borate species that may be present in the buffer. However, assuming sodium tetraborate decahydrate predominates, the mass percentage solution concentration (m/m) can be calculated using the molecular weight of sodium tetraborate decahydrate and the molar concentration/density of the solution reported in the lot-specific Certificate of Analysis.
The specifications for solution molar concentration are between 0.127 M and 0.140 M, whereas the specifications for solution density are between 1.000 g/mL and 1.020 g/mL (at 20 °C). The maximum and minimum specified percentage solutions (m/m) can be calculated from these values. The mass percentage solution is expressed as the total mass of the solute divided by the total mass of the solution, multiplied by 100.
Using the minimum specified molar concentration of 0.127 M as an example, this can be expressed as 0.127 moles per liter of solution or 0.127 moles per 1000 mL of solution. Multiplying this 0.127 moles per 1000 mL of solution by the molecular weight of the assumed sodium tetraborate decahydrate (381.37 g/mol), dividing it by the maximum specified density (1.020 g/mL), and multiplying the result by 100 yields a minimum percentage solution (m/m) of 4.75%.
Repeating the calculation using the maximum specified molar concentration of 0.140 M and the minimum specified density of 1.000 g/mL yields a maximum percentage solution (m/m) of 5.34%. An exact percentage solution (m/m) would need to be calculated from the specific values listed in the lot-specific Certificate of Analysis.
