In techniques like AAS, there needs to be a calibration curve run prior to determining quantitatively how much of an ion is present. How could a qualitative technique like the ones in the lab HELP make the quantitative technique go faster?

How is the concentration of Cl determined by mercuric nitrate? Is there a color change at various levels? (similar to the Cl test for swimming pools and you'd have to match a particular color to a particular concentration?)