Section 876.1400 - Stomach pH electrode(a)Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH (hydrogen ion concentration). The pH electrode is at the end of a flexible lead which may be inserted into the esophagus or stomach through the patient's mouth. The device may include an integral gastrointestinal tube.(b)Classification. Class I. The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter.48 FR 53023, Nov. 23, 1983, as amended at 61 FR 1122, Jan. 16, 1996