Yes.
Samples for total metals can be submitted unpreserved. Total metals analyses are also subject to acid digestion, so regardless of what the chemical dynamics in a container of water may shift the equilibrium towards, the subsequent acid digestion sample preparation procedure will efficiently solubilize all target parameters, for quantification.
It is important to note the need for preservation on the Chain of Custody, when submitting samples, so that the proper preservative is added as quickly as possible.