::Combination pH Electrodes ::

Combination pH Electrodes

Dimensions		Description	Type	pH Range	Temp ⁰C	Applications
Length (mm)	Dia (mm)	Description	Type	pH Range	Temp ⁰C	Applications
Combined pH Electrodes
150	12	pH Combined Electrode (Glass)	ST 21	0-14	20-100	General Purpose pH measurement / Soil
150	12	pH Combined Electrode (Epoxy)	ST 22	0-14	20-80	"
150	12	pH Combined micro type	ST 23	0-14	20-100	pH measurement in Test Tube 0.2…0.4ml
150	12	pH Combined Electrode Flat surface	ST 24	0-14	20-100	pH measurement on surfaces, skin, paper, leather, Iso-electric gel focusing

Combination pH Electrodes
Micro Combination pH Electrodes measure small samples and are available in a variety of sizes, including a needle tip to pierce septa and a long-bodied electrode. With Ag/AgCl references, Micro-pH electrodes provide fast, stable responses with a minimum of sample.

pH electrodes are tough epoxy bodied combination pH electrodes with a gel filling so you never need to worry about electrode maintenance or refilling again. They are compatible with nearly every pH meter straight out of the box or with a simple adapter cable.

Single or double junction for demanding application
Choice of sizes and lengths available. .

Standard models feature an extended body which protects the sensitive pH sensing bulb. You can even use an EpoxyTough to stir your sample with to get a fast stable reading.

Specifications:

pH Range: 0-14pH
Response: 95% in one second (bulb types)
Body material: Glass or Epoxy
Isopotential Point: 7.0 pH (0 mV)
Offset: +/- 0.20 pH
Cable length : 75cm
Connectors: BNC

Adapters are available for DIN and US STD. Other connectors are also available as special order.

pH Electrode Maintenance

The entire glass membrane must always be clean. Rinsing the membrane with distilled water will often suffice for aqueous solutions. Rinsing the electrode with a mild detergent solution once a week will be beneficial. An alkaline hypochlorite solution can be used to clean electrode membranes subjected to solutions containing fat or proteins.
High temperature measurements, compounded by constant use in strong alkaline solutions or weak solutions of hydrofluoric acid will drastically reduce the lifetime of the electrode, since the glass membrane will slowly dissolve.
Dry storage is recommended if the electrode will not be used for two weeks or more. Before use, the electrode should be soaked well. After overnight soaking, rinsing, soaking in a buffer of pH = 4, and again rinsing, the electrode should be ready for use. If a shorter soaking time is necessary, the electrode should be calibrated frequently to adjust for drifting potentials.
Trapped air bubbles around the inner reference electrode will produce an unstable reading. Swing the electrode in an arc or tap it gently to remove the bubbles. The electrode may have to be heated gently to approximately 60° C in a water bath if the air bubbles are trapped by KCl solution.
In order to establish a stable, hydrated glass membrane, new or dry-stored electrodes should be soaked overnight in 0.1 M HCl.

Trouble Shooting

The electrode cable and the electrode plug must be kept clean and dry. The electrodes may be checked by performing an electrode calibration.

Be sure to use distilled or deionized water when performing a calibration.
If the electrode fails to respond as expected, repeat the calibration.
If the electrode still fails to respond as expected, substitute another electrode that is known to be in good working order for the questionable electrode. If the problem persists and you are using an electrode pair, try the same routine with a working reference electrode.
If the problem persists, the standards may be of poor quality. Open fresh standards and attempt to calibrate the electrode again.
If another electrode is not available for test purposes, or if the electrode in use is suspect, review the calibration procedure and be sure to:
- Clean and rinse the electrode thoroughly.
- Prepare the electrode properly.
- Use the proper filling solution.