Cannot see why not . Do they make universal indicator paper these days

Apple cider vinegar is what I use anyway when I make chutney and pickles
But thinking about this apple cider vinegar is usually 4 to 5 % acid not sure how that works out pH* wise but it is never more than that as the microbes die at that acid concentration other vinegar concentrations depend on an industrial scale process and I suspect neither of us want to go there .
David
*too many years since my chemistry degree
Living in Anjou , France,
For the many not for the few
http://www.permies.com/t/80/31583/projects/Permie-Pennies-France#330873