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Electrodes Catalog

Catalogue · pH · Ion selective · Conductivity

Laboratory Electrodes Catalog

Start from your sample, see the recommended electrode with a photo, then open the product page. All models, the full selection matrix and connector compatibility are below.

Find a pH electrode by sample

Pick the group that matches your sample. The electrodes shown are the manufacturer’s recommended choice for that sample.

pH electrodes

All 20 models, grouped by what they are built for.

Conductivity electrodes

Choose the cell constant by the expected conductivity of the sample.

0.055–2 μS/cm

Ultrapure water

k≈0.01
1–200 μS/cm

Pure, ion-exchange water

k≈0.1
2–3000 μS/cm

Tap, drinking, rain, surface water

k≈1
20 μS/cm – 200 mS/cm

Wastewater, seawater, juice

k≈1 or k≈10
above 200 mS/cm

High-salt industrial wastewater

k≈1, two-point calibration

ATC = built-in temperature sensor. Without ATC, use a separate temperature probe or enter the temperature manually on the meter.

Ion selective electrodes

Electrode guide: how electrodes differ

Shape, body material, junction and connector decide which electrode suits a sample and a meter. The short explanations below help you read the tables above.

pH sensor shape

The shape of the glass membrane decides what kind of sample the electrode can touch.

Spherical pH sensor

Spherical

General use in common solutions.

Best for: liquids, pH 2–12. Most electrodes in this catalogue.

Micro spherical pH sensor

Micro spherical

Small liquid volumes, from about 200 μL.

Best for: test tubes and small vessels. See slender PRO6146.

Flat pH sensor

Flat

Surface measurement.

Best for: skin, leather, paper. See PRO6145 and PRO6138.

Conical blade spear pH sensor

Conical (blade spear)

Semi-solid products.

Best for: cheese, meat, fruit and soil. See PRO6144 and PRO6137.

Body material

The body material decides chemical resistance and how robust the electrode is.

Glass

Glass

Lead-free glass. Easy to clean and suitable for organic solutions, but breakable and sensitive to fast temperature changes.

Used for: pH and conductivity electrodes.

Plastic

Plastic

Polycarbonate, epoxy, PP or POM. Unbreakable and resistant to knocks. Not suitable for organic solutions.

Used for: pH, ion selective and DO electrodes.

Stainless steel

Stainless steel

Heat resistant.

Used for: temperature probes and blade spear tips.

Titanium alloy

Titanium alloy

Resistant to current and magnetic field effects.

Used for: conductivity electrodes for ultrapure water.

Junction

The junction is the contact between the reference electrolyte and the sample. It decides how well the electrode copes with dirty, viscous or very pure samples.

Ceramic junction

Ceramic

Good permeability, stable potential.

Standard choice for clean aqueous samples.

Single fabric junction

Single fabric

Good permeability, stable potential, cost-effective.

Standard polycarbonate electrodes.

Porous PTFE junction

Porous PTFE

Allows a higher flow rate of reference electrolyte.

Low-conductivity water: PRO6143.

POM junction

POM

Solvent resistant.

Non-refillable composite electrodes.

Fixed ground glass junction

Fixed ground glass

Allows a higher flow rate of reference electrolyte.

Ultrapure water: PRO5981.

Movable ground glass junction

Movable ground glass

Higher electrolyte flow, resistant to contamination.

pH titration and non-aqueous titration.

Open junction

Open

Easy to clean, does not block.

Emulsions and suspensions: PRO6142.

Movable plastic sleeve junction

Movable plastic sleeve

Easy to clean and to change the filling solution.

Emulsions and suspensions: PRO6041.

Reference system: Ag/AgCl or Longlife

Standard electrodes use an Ag/AgCl reference. The special-application series uses a Longlife reference, which compared with Ag/AgCl gives a longer service life, a wider temperature range and a potential that stays stable for longer.

Highlight: 3 in 1 pH composite electrode

A composite electrode joins the pH indicator electrode and the reference electrode in one body. A 3 in 1 electrode adds a temperature probe, so one sensor delivers pH and temperature and the meter compensates automatically.

  • pH indicator electrode + reference electrode + temperature probe
  • BNC(Q9) for pH and 4-pin aviation for temperature
  • Easy-fill port for 3 M KCl
  • One cable set, less clutter in the beaker

3 in 1 pH electrode PRO4153

Use and maintenance

Before use

Remove the protective cap and rinse the tip. On refillable electrodes check the electrolyte level and open the fill port during measurement. Calibrate with fresh buffers.

During measurement

The sample must cover both the membrane and the junction. Stir gently, wait for a stable reading and rinse between samples.

After use

Rinse, close the fill port and put the cap back with storage solution. Do not store a pH electrode dry or in distilled water.

Regular care

Top up 3 M KCl on refillable electrodes. Clean fat and protein residues after food samples. Replace the electrode when response becomes slow or calibration slope drops.

Conductivity: what is the cell constant?

The cell constant (k) describes the geometry of the two electrodes in the sensor and directly affects measurement accuracy. Low conductivity needs a low constant, high conductivity a high one.

Conductivity cell k=0.01

k = 0.01

Ultrapure water, 0.05–20 μS/cm.

PRO6158 · PRO6159

Conductivity cell k=0.1

k = 0.1

Pure and ion-exchange water, 0.05–200 μS/cm.

PRO6157

Conductivity cell k=1

k = 1

Tap, surface and waste water, 2–20000 μS/cm.

PRO6156 · PRO6155 · PRO6154 · PRO6153

Conductivity cell k=10

k = 10

Brines and concentrated solutions, 2000–200000 μS/cm.

PRO6160

Platinum conductivity cell

Platinum

Used for lower conductivity. In low-conductivity solutions it gives a stable reading.

Platinum black conductivity cell

Platinum black

Used for higher conductivity. In low-conductivity solutions it adsorbs electrolyte strongly and the reading becomes unstable.

Conductivity electrode without ATC

Without ATC

The temperature must be measured with a separate probe or thermometer.

Conductivity electrode with ATC

With ATC

The electrode measures temperature and conductivity at the same time.

Full pH electrode selection matrix

Every sample type against every pH electrode. Scroll sideways on small screens.

Sample type PremiumPRO5979 Alkali-resistantPRO6150 CleanablePRO6041 Low-maintenancePRO6142 Low-conductivityPRO6143 HF acid titrationPRO6151 HF-resistantPRO6152 Ultrapure waterPRO5981 High-temperaturePRO6149 Blade spear, refillablePRO6144 Flat, glassPRO6145 Long 260 mmPRO6147 Slender 6 mmPRO6146 RoHS lead-free glassPRO6148 3 in 1 with temperaturePRO4153 Standard refillablePRO6134 Standard unfillablePRO6136 Blade spear, unfillablePRO6137 Flat, polycarbonatePRO6138 Glass bodyPRO6140
Aqueous solutions
Dilute acids and alkalis ● ● ● ● ● ●
Fertilizer ● ●
Aldehydes, ketones, alcohols, ethers ○
Fixing and electroplating solutions ○ ○ ○ ● ○ ○
Food
Yogurt, cheese, butter ● ● ○ ○
Jam ● ● ○ ○
Cooking oils ● ○ ○
Soy sauce, vinegar ● ● ○ ○
Meat, fish ● ● ● ●
Fruit, vegetables ● ● ● ●
Paste ● ● ● ●
Beverages
Beer, juice, coffee, carbonated drinks ● ● ● ○
Pure, ion-exchange and distilled water ● ●
Pharmaceutical and biological samples
Plasma, gastric juice, urine ○ ● ● ○ ●
Pharmaceutical formulations ● ●
Protein-containing samples, enzyme solutions, agar media ○ ● ● ●
Pure and distilled water, water for injection ●
Tris buffer ●
Microtubes, plates, micro containers, tubes ● ●
Chemical reagents and solvents
Dyes, colouring agents, ink ● ● ○ ○
Water-based paint, varnish, coating, latex ● ● ○ ○
Sizing agents ● ● ○ ○
Bleaching liquids, rinses, plating solutions ● ●
Boiler water ● ●
Leather, paper, textile ● ●
Cosmetics
Gel, soap, shampoo, hair dye, lotion ● ● ○ ○
Skin ● ●
Environmental monitoring
Tap and drinking water (approx. 100 μS/cm) ● ● ● ● ● ●
Surface and underground water ●
Municipal wastewater ● ●
Strongly acidic samples (pH below 1) ●
Strongly alkaline samples (pH above 10) ●
High-viscosity samples ●
High-electrolyte samples, high-salt industrial wastewater ●
Samples with conductivity above 100 μS/cm ●
Ultra-pure and deionised water (below 100 μS/cm) ●
Acidic wastewater with fluorine (up to 2000 ppm HF) ●
Acidic samples with high fluorine content (hydrofluoric acid) ●
Rain ● ●
Soil ● ○ ●
Soil leachate ○ ● ● ○ ○
Mud ● ● ○
Vessels and temperature
Large containers, reactors ●
High temperature (80–100 °C) ●

● Recommended   ○ Applicable, service life may be shorter in this sample.

Connector and meter compatibility

Check the connector on your meter before ordering.

BNC Q9 connector

BNC(Q9)

Connects directly to pH and ion meters with a BNC input.

S7 connector

S7

Screw head on the electrode. An S7–BNC(Q9) cable is needed for meters with a BNC input.

4-pin aviation connector

BNC(Q9) + 4-pin aviation

3 in 1 electrode: BNC for pH, 4-pin aviation for temperature. The meter needs both inputs.

5-pin aviation connector

5-pin aviation

Conductivity electrodes for meters with a 5-pin aviation input.

8-pin MiniDin connector

8-pin MiniDin

Conductivity electrode for EC600L and M600L meters.

Sales and support
COLO Lab Experts
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Phone: +386 70 713 437 · Email: sales@colo.si · Web: colo.si
We supply laboratories and distributors across Europe. B2B prices are net, without VAT.

Need help choosing an electrode?

Tell us the sample, the meter model and its connector, and we will confirm the right electrode and cable.

Recommendations follow the manufacturer’s selection guide; confirm meter compatibility before ordering.