Changes in electrophoresis buffer pH is an important parameter to consider when optimizing already existing reagents or conditions or testing new reagents/conditions for agarose gel electrophoresis.
To analyze the buffer pH change, take a few milliliter (≈ 2 ml) of electrophoresis buffer from both anode and cathode chamber and analyze their pH by pH meter.
Sanderson et al., 2014. Modification of gel architecture and TBE/TAE buffer composition to minimize heating during agarose gel electrophoresis. Anal Biochem. 454, 44-52. PMID-24637158; Full-Text Links: sciencedirect, PMC4021863