421.5 g/kg = 423.565 PSU
| g/kg | PSU |
|---|---|
| 406.5 g/kg | 408.492 |
| 411.5 g/kg | 413.516 |
| 416.5 g/kg | 418.541 |
| 421.5 | 423.565 |
| 426.5 g/kg | 428.59 |
| 431.5 g/kg | 433.614 |
| 436.5 g/kg | 438.639 |
421.5 g/kg = 423.565 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)