Routine tests for surface dealkalization in the glass container industry all generally aim to evaluate the amount of alkali extracted from the glass when it is rinsed with or exposed to purified water.  For example, dealkalization can be quickly checked by introducing a small volume of distilled water to a freshly made bottle and rolling the bottle gently to pass the water completely over its inside surface.  The pH of the rinse water is then measured; untreated containers will tend to yield a slightly alkaline pH in the 8-9 range due to extracted alkali, while dealkalized containers tend to yield a pH that remains approximately neutral.  
A much more thorough version of this test is outlined in various international and domestic testing standards for glass containers, all with comparable methodologies.  These tests evaluate the hydrolytic stability of the containers under more severe conditions, wherein containers, filled close to capacity with purified water, are covered and then heat-cycled in an autoclave at 121 °C for 1 hour.  After cooling to room temperature, the water is titrated with acid to evaluate the pH of the water, and therefore the equivalent amount of alkali extracted during the heat cycle.  The alkali content of the rinse water can also be evaluated more directly by chemical analysis of the rinse water, as outlined in more recent versions of the European Pharmacopoeia.  According to the Pharmacopoeia standards, internally treated or dealkalized soda-lime glass containers are designated as "Type II" containers, thus setting them apart from their untreated counterparts due to their improved resistance to product interactions (as opposed to "Type III", which is standard, untreated soda-lime glass, or "Type I", which is reserved for highly resistant borosilicate glass).
While not routine, dealkalization can also be measured in a variety of other ways.  Since dealkalized surfaces are more chemically durable, they are also more resistant to weathering reactions, and appropriate evaluation of this parameter can give indirect evidence of a previously dealkalized surface.  It is also possible to evaluate dealkalization through the use of advanced, surface analytical techniques such as SIMS or XPS, which give direct measurements of glass surface composition.