221.5 g/kg = 222.585 PSU
| g/kg | PSU |
|---|---|
| 206.5 g/kg | 207.512 |
| 211.5 g/kg | 212.536 |
| 216.5 g/kg | 217.561 |
| 221.5 | 222.585 |
| 226.5 g/kg | 227.61 |
| 231.5 g/kg | 232.634 |
| 236.5 g/kg | 237.659 |
221.5 g/kg = 222.585 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)