How to convert micromolar concentrations into molar quantities, when the volume is also known
Molar concentration, or molarity, is moles per unit volume. If you know concentration and sample volume, you can calculate the moles of a particular component in the sample. Since your concentrations are already in micro-molar, when you multiply by the sample volume (in liters), you will have the micro-moles of each component. 

For the Mn result, you will get the mass of Mn (in micrograms) when you multiply the test result by the sample volume, so you can convert that to moles using the molar mass of Mn.