pH composite electrode for ph meter
The electrode that combines the pH glass electrode with the reference electrode is called the pH composite electrode. Plastic shell is called plastic pH composite electrode. The case of glass is called glass pH composite electrode. The biggest advantage of the composite electrode is combined, easy to use. The structure of the pH composite electrode is mainly composed of an electrode bulb, a glass supporting rod, an internal reference electrode, an internal reference solution, a shell, an external reference electrode, an external reference solution, a liquid junction, an electrode cap, an electrode lead and a socket.
⑴ electrode bulb: It is a hydrogen-functional lithium glass melt blown, spherical, film thickness of about 0.1 ~ 0.2mm, resistance <250 megohms (25 ℃).
⑵ glass support tube: is to support the electrode bulb glass tube, made of lead glass with excellent electrical insulation, the expansion coefficient should be consistent with the electrode bulb glass.
⑶ reference electrode: silver / silver chloride electrode, the main role is to refer to the electrode potential, requiring its potential stability, the temperature coefficient of small.
⑷ reference solution: zero potential 7pH reference solution is a mixture of neutral phosphate and potassium chloride solution, the glass electrode and the reference electrode to form a battery zero potential pH, mainly depends on the internal reference solution pH Value and chloride ion concentration.
(5) Electrode Molded Case: Electrode Molded Case is a shell that supports glass electrode and liquid junction and holds external reference solution. It is molded by polycarbonate plastic.
⑹ external reference electrode: Silver / silver chloride electrode, the role is to provide and maintain a fixed reference potential, requiring stable potential, good reproducibility, the temperature coefficient of small.
⑺ external reference solution: 3.3mol / L of potassium chloride gel electrolyte, easy to drain, without adding.
⑻ sand core liquid junction: liquid junction is the structure of the external reference solution and the measured solution of the connecting parts, the required amount of penetration stability.
⑼ electrode lead: low-noise metal shielding wire, the inner core and reference electrode connected, the shield and the outer reference electrode connection.