I went on alkaline diet a few ys ago that was recommended to get rid of a gout problem. My ph as measured in urine tests over a couple weeks increased ph from my normal 5.5 to 7.2. PH returned to 5.5 a couple weeks after returning to regular diet.
I have brought this up in previous posts. Neither urinary, nor salivary pH reflect blood pH. The only way to determine blood pH levels is with blood tests.