Selecting the correct electrode requires matching the sensor bulb glass type and junction structure to your sample. For general aqueous solutions, a lithium glass bulb is standard; however, for high-temperature or strong alkaline samples, you must specify high-temp resistant or low-sodium error glass. Additionally, consider the reference system: a double junction design is critical when testing samples containing proteins, heavy metals, or sulfides to prevent electrolyte contamination and junction clogging.