Which of the following is NOT a method for measuring chloride?

Gravimetric methods are indeed a valid approach to measuring chloride levels, often involving the precipitation of chloride as silver chloride (AgCl) and subsequent weighing. However, in the context of the methods explicitly associated with chloride measurement, the options mentioned typically associate closely with specific analytical techniques designed to directly assess chloride ion concentration in various samples.

Argentometric methods, for example, are specifically designed for the determination of halides, including chloride, through the precipitation reaction with silver ions.

Mercuric nitrate is another recognized method for determining chloride content, commonly used as a titrant in quantitative analysis.

Given that gravimetric methods are widely used for the quantitation of many substances, but not solely or directly identified with chloride in the same distinct manner as argentometric techniques, the answer centers on the specialized context of chloride measurement.