What is the unsuccessful blood donation?

It should be that the PH value in your blood is high. I have encountered such a thing once before. At that time, I made it clear that my PH was more than half higher than normal. The staff also asked me to go again in a month. What I need to do is pay more attention to rest a week before donating blood, don't eat irritating food, don't catch a cold, don't take other drugs and don't drink, get enough sleep the night before and have breakfast in the morning (mainly light).