# Converting Disolved Oxygen from micromole/L to millimole/kg

I have dissolved oxygen data that is in units of µmol/liter.

I need to convert it to mmol/kilogram.

I have been told by someone who knows more about chemistry than I do (but only a little bit more) that I need to know the mass of my sample as well (which I don't know).

So only knowing my original DO data (in µmol/L) and the density of SW (assume 1.027 g/cm³), how does one convert the data to mmol/kg?

• Depends a lot on what the oxygen is dissolved in. If it is in water, then the conversion l → kg is easy. – Jan Oct 7 '15 at 7:20
• The O2 is dissolved in seawater. – Vinterwoo Oct 7 '15 at 15:30

The conversion is relatively straightforward. For a solution with concentration $X$:
$$(X\ \mathrm{\mu mol/L}) \times (1\ \mathrm{mmol}/1000\ \mathrm{\mu mol})\times(1\ \mathrm L/1.027\ \mathrm{kg}) = 0.0009737\ X\ \mathrm{mmol/kg}$$