Where the liquid is does not matter - as long as you didn't suck air up when you filled the syringe. The plunger tells you how much was dispensed, and unless you have a way of titrating with the syringe pointing up, you always get reagent coming out. In the rare instance you need more reagent (like when dosing Mg to get rid of byropsis and it's off the charts), just add more and continue titrating.