I found this, quite interesting..?
Unblended for Optimal pH
Vodka is a “neutral spirit” and should have a pH in the 6.0–7.0 range. That is, not too acidic, not too basic. But many distillers add citric-based blenders to their vodka to take advantage of a tax loophole. It saves them money, but drops their pH down to the 4.0-4.5 range.
UV is never blended and maintains a pH of 6.0—in the same neighborhood as super-premium and luxury brands like Grey Goose, Belvedere, Stolichnaya, Skyy, Smirnoff and Ketel One.
Here’s a little chart that you might find of interest, taken right from the EPA website.
If you want to test a vodka’s acidity for yourself, just pour about an ounce of it into a few ounces of Bailey’s Irish Cream Liqueur. If it begins to curdle, even slightly, there’s acid in the vodka.