Electrodes

pH Electrodes for the laboratory

We offer pH electrodes or combination electrodes for pH measuring devices from Mettler Toledo, WTW and SI Analytics. The electrodes can be used in a wide range of applications such as pH measurements in food testing. The chemical composition, homogeneity, temperature, process pressure and the pH range of the sample are important criteria when choosing the right electrode. Contact our customer service to assist you on selecting the right electrode.

A pH electrode selection guide can be found here.

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Items 1-50 of 918

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Product Image of pH combination electrode InLab Micro
pH combination electrode InLab Micro
Item number: MR51343160
Brand: Mettler-Toledo

In stock

€365.00
Product Image of pH combination electrode InLab Routine Pt1000
pH combination electrode InLab Routine Pt1000
Item number: MR51343056
Brand: Mettler-Toledo

In stock

€322.00
Product Image of pH electrode LE438 (plastic, 3-in-1)
pH electrode LE438 (plastic, 3-in-1)
Item number: MR51340242
Brand: Mettler-Toledo

In stock

€193.80 €204.00
Product Image of pH Combination Puncture Electrode SE104N, Body length: 65/25 mm, material: plastic (Noryl PPO), pH range: 2 to 13
pH Combination Puncture Electrode SE104N, Body length: 65/25 mm, material: plastic (Noryl PPO), pH range: 2 to 13
Item number: KNSE104N
Brand: Knick

In stock

€353.07
Product Image of pH/Pt 1000 combined electrode SE100N, Body length: 165 mm,  material: glass, pH measurement range: 0 to 14
pH/Pt 1000 combined electrode SE100N, Body length: 165 mm, material: glass, pH measurement range: 0 to 14
Item number: KNSE100N
Brand: Knick

In stock

€325.33
Product Image of Conductivity electrode TetraCon 325
Conductivity electrode TetraCon 325
Item number: WW301960
Brand: WTW

In stock

€534.85 €563.00
Product Image of WP 90/3 3 exchange membrane heads
WP 90/3 3 exchange membrane heads
Item number: WW202725
Brand: WTW

In stock

€176.00
Product Image of pH-Combination electrode Sensolyt, Model name : SensoLyt® SEA
pH-Combination electrode Sensolyt, Model name : SensoLyt® SEA
Item number: WW109115
Brand: WTW

In stock

€305.00
Product Image of SenTix Mic-D combined pH-electrode
SenTix Mic-D combined pH-electrode
Item number: WW103660
Brand: WTW

In stock

€367.00
Product Image of SenTix ORP ORP combination electrode
SenTix ORP ORP combination electrode
Item number: WW103648
Brand: WTW

In stock

€252.00
Product Image of SenTix Sp Spear-type pH-combination electrode
SenTix Sp Spear-type pH-combination electrode
Item number: WW103645
Brand: WTW

In stock

€359.00
Product Image of SenTix 81 standard pH combination electrode with built-in temperature sens
SenTix 81 standard pH combination electrode with built-in temperature sens
Item number: WW103642
Brand: WTW

In stock

€283.00
Product Image of SenTix 61 standard pH combination electrode
SenTix 61 standard pH combination electrode
Item number: WW103640
Brand: WTW

In stock

€185.00
Product Image of pH combination electrode SenTix 41-3
pH combination electrode SenTix 41-3
Item number: WW103636
Brand: WTW

In stock

€288.00
Product Image of pH-combination electrode SenTix 41, with integrated temperature sensor
pH-combination electrode SenTix 41, with integrated temperature sensor
Item number: WW103635
Brand: WTW

In stock

€228.95 €241.00
Product Image of SenTix 21 basic pH combination electrode
SenTix 21 basic pH combination electrode
Item number: WW103631
Brand: WTW

In stock

€159.00
Product Image of KCl-250 KCl solution for Cleaning and storage of electrodes, Reference electrolyte1 bottle with 250 ml KCl solution 3M/l
KCl-250 KCl solution for Cleaning and storage of electrodes, Reference electrolyte1 bottle with 250 ml KCl solution 3M/l
Item number: WW109705
Brand: WTW

In stock

€26.50
Product Image of Memosenselectrode SE102NMS
Memosenselectrode SE102NMS
Item number: FG4318-003
Brand: Funke Gerber

In stock

€467.43
Product Image of Ionselective Combination Electrode CU 60, with Plug Head, for Determination of Kupfer Ion, solid state body Electrode
Ionselective Combination Electrode CU 60, with Plug Head, for Determination of Kupfer Ion, solid state body Electrode
Item number: SI285130430
Brand: SI Analytics
€1,717.20
Product Image of Ionselective Combination Electrode BR 60, with Plug Head, for Determination of Bromid Ion, solid state body Electrode
Ionselective Combination Electrode BR 60, with Plug Head, for Determination of Bromid Ion, solid state body Electrode
Item number: SI285130420
Brand: SI Analytics
€1,359.64
Product Image of Ionselective Combination Electrode I 60, with Plug Head, for Determination of Iodid Ion, solid state body Electrode
Ionselective Combination Electrode I 60, with Plug Head, for Determination of Iodid Ion, solid state body Electrode
Item number: SI285130410
Brand: SI Analytics
€1,405.93
Product Image of Ionselective Combination Electrode AG-S 60, with Plug Head, for Determination of Sulfid Ion, solid state body Electrode
Ionselective Combination Electrode AG-S 60, with Plug Head, for Determination of Sulfid Ion, solid state body Electrode
Item number: SI285130400
Brand: SI Analytics
€1,439.49
Product Image of Ionselective Combination Electrode CN 60, with Plug Head, for Determination of Cyanid Ion, solid state body Electrode
Ionselective Combination Electrode CN 60, with Plug Head, for Determination of Cyanid Ion, solid state body Electrode
Item number: SI285130390
Brand: SI Analytics
€1,359.64
Product Image of Ionselective Combination Electrode CA 60, with Plug Head, for Determination of Calcium Ion, Matrix Electrode
Ionselective Combination Electrode CA 60, with Plug Head, for Determination of Calcium Ion, Matrix Electrode
Item number: SI285130380
Brand: SI Analytics
€1,385.10
Product Image of Ionselective Combination Electrode K 60, with Plug Head, for Determination of Kalium Ion, Matrix Electrode
Ionselective Combination Electrode K 60, with Plug Head, for Determination of Kalium Ion, Matrix Electrode
Item number: SI285130370
Brand: SI Analytics
€1,385.10
Product Image of Ionselective Combination Electrode NO 60, with Plug Head, for Determination of Nitrat Ion, Matrix Electrode
Ionselective Combination Electrode NO 60, with Plug Head, for Determination of Nitrat Ion, Matrix Electrode
Item number: SI285130360
Brand: SI Analytics
€1,385.10
Product Image of Ionselective Combination Electrode Cl 60, with Plug Head, for Determination of Chlorid Ion, solid state body Electrode
Ionselective Combination Electrode Cl 60, with Plug Head, for Determination of Chlorid Ion, solid state body Electrode
Item number: SI285130350
Brand: SI Analytics
€1,359.64
Product Image of Ionselective Combination Electrode F 60, with Plug Head, for Determination of Fluorid Ion, solid state body Electrode
Ionselective Combination Electrode F 60, with Plug Head, for Determination of Fluorid Ion, solid state body Electrode
Item number: SI285130340
Brand: SI Analytics
€1,359.64
Product Image of pH-Combination Electrode AquaLine  AL 90 pH 5x, with Screw Plug Head, plastic Shaft, Fiber diaphragm
pH-Combination Electrode AquaLine AL 90 pH 5x, with Screw Plug Head, plastic Shaft, Fiber diaphragm
Item number: SI285113180
Brand: SI Analytics
€206.00
Product Image of pH-Combination Electrode AquaLine AL 70 pH-20M-X, with Screw Plug Head, Glass Shaft, ceramic diaphragm
pH-Combination Electrode AquaLine AL 70 pH-20M-X, with Screw Plug Head, Glass Shaft, ceramic diaphragm
Item number: SI285113080
Brand: SI Analytics
€312.00
Product Image of pH-Combination Electrode L 9090- Pt1000-VP, with Screw Plug Head, Glass Shaft, Platinum diaphragm
pH-Combination Electrode L 9090- Pt1000-VP, with Screw Plug Head, Glass Shaft, Platinum diaphragm
Item number: SI285090120
Brand: SI Analytics
€441.00
Product Image of Swing Arm Electrode Holder
Swing Arm Electrode Holder
Item number: PRQA854X
Brand: Dissolution Accessories
€130.66
Product Image of Adapter BNC Socket to DIN
Adapter BNC Socket to DIN
Item number: PRQA833X
Brand: Dissolution Accessories
€88.32
Product Image of Conductivity Standard, 500,000 µS/cm @25 °C, 500 ml
Conductivity Standard, 500,000 µS/cm @25 °C, 500 ml
Item number: PRQS1042
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 200,000 µS/cm @25 °C, 500 ml
Conductivity Standard, 200,000 µS/cm @25 °C, 500 ml
Item number: PRQS1038
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 100,000 µS/cm @25 °C, 500 ml
Conductivity Standard, 100,000 µS/cm @25 °C, 500 ml
Item number: PRQS1034
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 20,000 µS/cm @25 °C, 500 ml
Conductivity Standard, 20,000 µS/cm @25 °C, 500 ml
Item number: PRQS1030
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 5,000 µS/cm @25 °C , 500 ml
Conductivity Standard, 5,000 µS/cm @25 °C , 500 ml
Item number: PRQS1026
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 500 µS/cm @25 °C, 500 ml
Conductivity Standard, 500 µS/cm @25 °C, 500 ml
Item number: PRQS1024
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 100 µS/cm @25 °C, 500 ml
Conductivity Standard, 100 µS/cm @25 °C, 500 ml
Item number: PRQS1020
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 50 µS/cm @25 °C, 500 ml
Conductivity Standard, 50 µS/cm @25 °C, 500 ml
Item number: PRQS1016
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 20 µS/cm @25 °C, 500 ml
Conductivity Standard, 20 µS/cm @25 °C, 500 ml
Item number: PRQS1012
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 10 µS/cm @25 °C, 500 ml
Conductivity Standard, 10 µS/cm @25 °C, 500 ml
Item number: PRQS1008
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 5 µS/cm @25 °C, 500 ml
Conductivity Standard, 5 µS/cm @25 °C, 500 ml
Item number: PRQS1004
Brand: Dissolution Accessories
€179.14
Product Image of Conductivity Standard, 1.3 µS/cm @25 °C, 250 ml
Conductivity Standard, 1.3 µS/cm @25 °C, 250 ml
Item number: PRQS1002
Brand: Dissolution Accessories
€179.14
Product Image of Redox-Electrode, Pt-billet, Glass, 130°C, Triple Junction, S8, 250 mm
Redox-Electrode, Pt-billet, Glass, 130°C, Triple Junction, S8, 250 mm
Item number: PRQR482X/TJ/250MM
Brand: Dissolution Accessories
€498.25
Product Image of Redox-SterProbe, 225 mm, Pt, S8
Redox-SterProbe, 225 mm, Pt, S8
Item number: PRQR454X
Brand: Dissolution Accessories
€362.02
Product Image of Redox-SterProbe, 120 mm, Pt, S8
Redox-SterProbe, 120 mm, Pt, S8
Item number: PRQR450X
Brand: Dissolution Accessories
€354.60
Product Image of Glass ORP half cell redox Electrode, refillable, 2xPt, 12x120mm
Glass ORP half cell redox Electrode, refillable, 2xPt, 12x120mm
Item number: PRQR411X
Brand: Dissolution Accessories
€215.59
Product Image of Redox-Electrode, Pt-rod, Epoxy, Ø 6 mm, BNC
Redox-Electrode, Pt-rod, Epoxy, Ø 6 mm, BNC
Item number: PRQR400X/6MM
Brand: Dissolution Accessories
€239.35

What is required for pH measurements?

A special measuring tool for hydronium ions which the pH value refers to, is required to measure the pH value. The principle of the measurement is based on a sensor with a glass membrane, which selectively detects hydronium ions and registers the reaction between the membrane and a sample solution. This glass electrode potential alone does not provide sufficient information, a second sensor is thus required which provides the reference potential for the pH sensor. To determine the pH value of the solution, the potential difference between these electrodes must be measured.

The reaction of the pH-sensitive glass electrode depends on the concentration of the H+ ions (or H3O+). Hence, pH is a measurement of both acidity and alkalinity, a selective measurement of hydronium ion activity. On the other hand, the reference electrode does not react to the concentration of the H+ ions in the sample solution and always delivers the same constant potential which is used to measure the potential of the pH sensor. The difference in potential between the two electrodes determines the pH of the solution. Since this potential is a linear function of the hydronium ion concentration in the solution, the concentration can be measured quantitatively.

Nowadays, the pH sensor and the reference sensor are very often housed in one electrode. This combination of reference and pH electrode is called a combined pH electrode. Each of these three types of electrodes is different and has its own characteristics and properties.

pH Electrodes

The pH electrode is the component that actually registers the pH of the solution. It consists of a glass shaft with a thin glass membrane at the lower end that is H+ ion sensitive. When this membrane comes into contact with an aqueous solution, the outside of the membrane glass forms a gel layer. A similar gel layer is also formed on the inside of the membrane glass as the electrode is filled with an internal aqueous electrolyte solution.

The H+ ions in and around the gel layer can - depending on the pH value and thus the H+ ion concentration of the measurement solution - either diffuse into or out of the layer. If the solution is alkaline, the H+ ions diffuse out of the layer and a negative charge is created on the outside of the membrane. Since the glass electrode has an internal buffer with a constant pH value, the potential on the inner surface of the membrane remains constant during the measurement. The potential of the pH electrode is therefore the difference between the inner and the outer charge of the membrane.

Reference electrodes

The task of the reference electrode is to provide a defined stable reference potential against which the potential of the pH sensor can be measured. To achieve this, the reference electrode must be made of glass, which is not sensitive to the H+ ions in the solution. It must also be open to the sample environment in which it is immersed. An opening or a diaphragm is made in the shaft of the reference electrode through which the inner solution or the reference electrolyte can flow into the sample. To obtain correct measurements, the reference electrode and the pH half-cell must be in the same solution.

The electrode construction consists of an inner reference element that is immersed in a defined reference buffer solution and has indirect contact with the sample solution via the diaphragm. This contact chain ensures a stable potential. There are several reference systems available, but the silver/silver chloride system is now used almost exclusively in laboratories. The potential of this reference system is defined by the reference electrolyte and the silver/silver chloride reference element. It is important for the reference electrolyte to have a high ion concentration and a low electrical resistance.

As the reference electrolyte flows into the sample during the measurement, pay attention to possible reactions between the reference electrolyte and the sample solution. Such reactions could affect the electrode and measurement.

Combined electrodes

Combined electrodes are much easier to handle than two separate electrodes and are therefore used very frequently today. In the combined electrode, the pH-sensitive glass electrode is surrounded concentrically by the reference electrode, which is filled with the reference electrolyte. The pH and reference components of the combined electrode have the same properties as the corresponding separate electrodes. The only difference is that they are integrated in a single electrode for easier handling. The use of individual pH and reference electrodes instead of a single combined electrode is only recommended if the two components of the combined electrode have a very different expected life span.

To further simplify pH measurements, a temperature sensor can be used together with the pH and the reference element in the same shaft. This enables temperature compensation while measurung pH. Such electrodes are also referred to as 3-in-1 electrodes.

pH and redox electrodes for every application

Electrodes may consist of different materials (very common are platinum, calomel or hydrogene electrodes) and are hence very versatile. They are knowned as single-rod measuring cells which are used to determine the pH value. However, the standard hydrogene electrode serves here as the reference electrode to determine the standard potential of redox couples. The most common ones are solid state electrodes containing of a metal and its dilution. Liquid electrodes such as quicksilver electrodes can also be used. 

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