What are the factors involved in collecting a urine sample?

If delivery of the urine specimen to the laboratory within one hour of collection is not possible, it should be refrigerated.

The answer said that various components of urine undergo decomposition in different periods of time. MY question is, if you refrigerate urine, when does pH begin decomposition and become more alkaline?

It is my understanding that after 30 minutes at room temperature, the pH portion of the test is no longer accurate. Let's say you catch the urine and within 5 minutes you refrigerate it. Will that pH be as accurate at 1 hour after collection as it would have been if tested within say, 20 minutes of being collected? How about 2 hours? 3 hours? and so on.