pH glass electrodes from Radiometer Analytical are made with highly shock-resistant glass, making them extremely tough. The average lifetime of a correctly maintained glass pH electrode is approximately 2 years.Certain electrodes are made with special glass for pH measurements in strongly alkaline solutions. These electrodes allow measurements within the 0 - 14 pH range without significant deviation from the theoretical response.Glass pH electrodes are always used in combination with reference electrodes. The zero pH of Red Rod glass pH electrodes when used with their recommended reference electrode is approximately pH 6.65. The zero pH of glass pH electrodes is approximately pH 6.65 when measured against a calomel reference electrode (e.g. REF421, XR110) and approximately pH 7.25 when measured against an Ag/AgCl reference electrode (e.g. REF321).
| Applications | Micro samples | General purpose | Alkaline samples |
 |  |  | |
| Type | pHG200 | pHG201 | pHG211 |
| Part no. Type 7 | E11M005 | ||
| Part no. BNC | E11M002 | E11M006 | E11M003 |
| pH range | 0 – 12 | 0 – 12 | 0 – 14 |
| Temperature range | 10 –100°C | -10 –100°C | 10 –100°C |
| Lower diameter | 4 mm | 7,5 mm | 7,5 mm |
| Reference system | Red Rod | Red Rod | Red Rod |
| Minimum | |||
| sample depth | 4 mm | 7 mm | 7 mm |
| Recommended reference electrode | REF200 | REF201/251 REF201 for general use |
| Applications | General purpose | Alkaline samples | |
| | | | |
| Type | pHG301 | pHG311 | XG250 |
| Part no. | E11M001 | E11M004 | B10B250 |
| pH range | 0 – 12 | 0 – 14 | 0 – 14 |
| Temperature range | 0 –80°C | 0 –80°C | 0 –80°C |
| Diameter | 12 mm | 12 mm | 10 mm* |
| Reference system | Ag/AgCl | Ag/AgCl | Ag/AgCl |
| Minimum sample depth | 12 mm | 12 mm | 12 mm |
| Recommended reference electrode | REF321 |
| Applications | Micro-samples | General purpose | General purpose | General purpose |
 |  |  | ||
| Model | REF200 | REF201 | REF251 | REF321 |
| Probe part no. | E21M008 | E21M009 | E21M001 | E21M002* |
| Reference system | Red Rod | Red Rod | Red Rod | Ag/AgCl |
| Liquid junction | Porous pin | Porous pin | Porous pin / porous pin | Porous pin |
| Temperature range | -10 -100°C | -10 -100°C | -10 -100°C | -5 -80°C |
| Lower diameter | 4 mm | 7.5 mm | 12 mm | 8 mm |
| Special features | For use with pHG200 | - | Double junction | - |
| Salt-bridge solution | Sat. KCl | Sat. KCl | Sat. KCl | 3 M KCl with sat. AgCl |
| Applications | Non-aqueous media | Voltammetry | Impedance |
| |  | | |
| Model | REF361 | XR300 | XR820 |
| Probe part no. | E21M003 | B20B300* | B20C820* |
| Reference system | Ag/AgCl | Ag/AgCl | Ag/AgCl |
| Liquid junction | Glass sleeve | Porous pin | Porous pin / fibre |
| Temperature range | -5 -80°C | -5 -80°C | -5 -80°C |
| Lower diameter | 12 mm | 8 mm | 8 mm |
| Special features | - | - | - |
| Salt-bridge solution | 3 M KCl with sat. AgCl | Sat. KCl + sat. AgCl | Sat. KCl + sat. AgCl upper res. |
*Screw cap electrode. Requires CL111 connection cable (part no. A94L111) for sensION+ meter compatibility