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Instruction Manual
EC620130 Series Combination pH Electrodes
Copyright © 2006 All rights reserved.
Eutech Instruments Pte Ltd
Version 1.1ML 68X068045 Rev 3 Jan 07
Blk 55, Ayer Rajah
Crescent, #04-16/24
Singapore 139949
+65 6778 6876
+65 67730836 fax
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PRODUCT SPECIFICATIONS
EC620130 Series Combination pH Electrodes
Catalog No. Description Length/Diameter (mm) Connector
EC- 620-130
EC- 620-131
EC- 620-132
EC- 620-133
Glass body, refillable 160/12 BNC EC-636-430
Glass body, gel-filled 130/12 BNC N/A
Plastic body, gel-filled 120/12 BNC N/A
Glass body, gel-filled,
spear tip
70 mm overall length,
25/6 mm insertion
BNC N/A
Refilling
Solution
PERFORMANCE SPECIFICATIONS
Specification / Model EC-620-130 EC-620-131 EC-620-132 EC-620-133
Body Material Glass Plastic Glass
pH Range 0 to 14 pH 2 to 14 pH
Temperature range 0 to 80 °C 0 to 60 °C 0 to 50 °C
Slope (out of Box) 59 +/- 3 mV/pH at 25°C (95 to 105% slope)
Zero point pH 7
Offset (asymmetry potential) 0 mV +/- 25 mV
Reference Junction Double Junction
Junction Type Open pore Double Pore
Membrane Shape Cylindrical Spear Tip
Improved junction and reference design for precise, reliable, FAST readings
Better junction. EC620130 series electrodes use a single-pore capillary reference junction—about 200
times larger than typical ceramic junctions—that makes the electrodes almost impossible to clog, even
in difficult samples. The unique junction design provides increased electrolyte flow, resulting in greater
contact between sample and reference, and ensuring fast, stable readings.
Better reference design. Along with the capillary junction, our electrodes feature double junction
design for enhanced performance. A diffusion barrier separates the silver chloride reservoir from the
reference electrolyte, permitting use of silver-free electrolytes and preventing silver chloride loss from
temperature induced variations. End result: an extremely stable reference potential, providing long
electrode life.
EC-620-130 Unique fluid-gel electrolyte and innovative junction design produces a high flowrate and
improved contact between reference electrolyte and sample. The result is faster response time and very
accurate readings. The double-liquid-junction system further extends the diffusion barrier, greatly
increasing electrode life in aggressive samples. It also performs well in liquids with low ion concentration
and in partly aqueous samples.
EC-620-131, -132, -133 Solid polymer-gel electrolyte offers the advantages of the EC620130 series
system in a maintenance-free version. Polymer gel provides a more stable matrix than other gelled
electrode reference systems, providing reliable results in very dirty, ion-weak or protein samples—even
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at low pH or in the presence of organic solvents. -133 offers a rugged spear tip is ideal for semi-solids or
soft foods.
GETTING STARTED
Each electrode has a unique serial number and is quality checked before it leaves the factory.
Electrodes are shipped with an electrode storage bottle containing electrode storage solution. This
storage solution will occasionally creep out and appear as dry white crystal residue on the electrode.
However, this will have no long-term effect on the electrode and can be simply rinsed off with clean
water.
Proper removal and insertion of the storage bottle is very important. Improper use can result in a
pressure build up either inside the electrode or the bottle resulting in electrolyte leakage through the fill
hole or the cap of the storage bottle. Proper use of the electrode storage bottle is shown in Figure 1.
EC-620-130 is a refillable electrode and will include a bottle of Skylite electrolyte solution along with a
separate syringe and nozzle for electrolyte refilling process. New electrodes are shipped filled with their
filling holes closed, so electrolyte refilling of a new electrode is generally not required. It is recommended
that the Skylite electrolyte (EC-636-430) be added using the syringe and nozzle provided when the
electrolyte level in the reference cavity (outer annular space) is lower than ¼ inch below the cap. Simply
open the fill hole at the top of the electrode by rotating the cap ring. Mount the nozzle to the syringe and
fill it with the Skylite electrolyte solution (The tip hole of the Skylite bottle can be enlarged by trimming
the tip so as to accommodate the diameter size of the nozzle during electrolyte collection into the
syringe). Insert the syringe’s nozzle into the fill hole of the electrode and gently inject the electrolyte into
the electrode. If the electrolyte level is not visible, the electrode may be filled to a capacity just beneath
the fill hole.
NOTE: EC-620-130 has a faster electrolyte flow rate as compared to other conventional refillable electrodes.
Therefore a fast drop in the level of its electrolyte will be observed and this should not be construed as a sign of
an electrode problem.
Mount the EC620130 series open-pore electrodes onto a suitable electrode holder and connect the
electrode to the meter. For EC-620-130 refillable electrodes, the fill hole should be in the open position
when in use. If necessary, rotate the cap ring to open the fill hole.
Immerse the electrode in pH 4 or pH 7 buffer for 5 to 10 minutes to condition the glass pH bulb.
ELECTRODE OPERATION
1) The level of electrolyte in the outer cavity should be kept above the level of the solution being
measured to prevent reverse electrolyte flow. The electrode needs only be immersed far enough to cover
both the glass pH sensing bulb and reference junction to obtain accurate readings.
2) If the electrode has not been hydrated (placed in solution for more than one hour), allow the
electrode to soak in a buffer (preferably pH 4) as needed prior to standardization or measurement. This
will help to optimize and re-establish the thin hydration layer on the sensing bulb that is critical to
accurate pH measurement.
3) Rinse the electrode with deionized or distilled water between samples. Note: wiping the sensing bulb
is not recommended as the thin hydration layer of the sensing bulb could be affected and electrical
charges may be produced.
4) Moving or touching the electrode cable may result in unstable readings due to the high impedance
(resistance) of the pH glass membrane.
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5) To eliminate temperature errors associated with the electrode, manual or automatic temperature
compensation (ATC) should be used for best accuracy. Since pH changes with temperature, the sample
temperature should always be noted with pH readings, for example, “pH 8.43 @ 23.2 °C”.
CALIBRATION/STANDARDIZATION
New EC620130 series pH electrodes are factory-tested to have an efficiency or “slope” of > 95%. The
theoretical pH response is 100% (59.16 mV/pH unit) and therefore the millivolt difference between pH
4.00 and pH 7.00 certified calibration standards at 25ºC should be 177.48 mV. A 95% slope means that a
new accumet electrode will have a response of at least 168.61 mV between these values. As electrodes
naturally age, this efficiency deteriorates. Periodic calibration against known standards is necessary to
ensure the electrode’s efficiency. Most pH meters have features to display the current electrode slope,
protection that warn users of a low slope (usually 90%) and/or features that prevents erroneous
calibrations.
After completing calibration with the meter, the measured pH reading of each calibration buffer can be
compared to the pH value indicated for each buffer at the actual temperature. A chart with pH at various
temperatures is usually found on the calibration standard packaging or label. Using one-point
standardization, proper response is indicated if the reading is within ± 0.05 pH units from the
standardization point within 30 seconds when using certified pH buffers . Multiple-point standardization
is recommended for more precise measurements. To provide a linear response in the area of interest, use
two calibration standards that bracket the expected sample pH.
STORAGE
Storing electrodes in distilled or deionized water is NOT recommended as it will deplete the hydration
layer of refillable electrodes, and decrease the life of non-refillable electrodes. The electrode storage
bottle containing storage solution can be used for short or long term storage. For refillable electrodes,
the electrolyte level in the outer cavity should be kept above the level of the solution being measured.
Ensure that the fill hole is closed when not in use.
TROUBLESHOOTING
SYMPTOM / CAUSE (REMEDY)
• No response, all buffers or samples read the same pH—usually pH 7.00 or 0 mV / Broken
sensing bulb or wiring problem (replace electrode), probe not connected to input (verify correct
channel selection when using multiple-channel meters), probe is not in contact with sample
(remove electrode storage bottle or rubber bulb guard), meter automatically has frozen reading
(verify that the ‘Hold’ feature or ‘Auto Read’ feature is set to ‘Off’ when using meters with this
feature).
• Slow response with excessive crystallization inside probe / electrolyte flow clogged from
supersaturated electrolyte (“flush & fill” by remove the filling solution through the fill hole with a
syringe or by shaking it upside down. Repeatedly flush and rinse the reference cavity with clean,
60-80°C water to dissolve crystals until removed. Replace filling solution and re-hydrate
electrode in storage solution or pH 4 buffer, (ensure fill hole is in open position). To prevent this
in the future, ensure that the fill hole is closed when electrode is not in use.
• Dried salt deposits present / electrolyte residue deposited on electrode surface –often with
new electrodes or periods of non-use. Simply dissolve the deposits in warm tap water followed
by a brief soak in pH 4 buffer.
• Slow Response, Noisy, unstable, or erratic readings / sensing bulb dry or dirty (clean
electrode with mild detergent & warm water and re-hydrate electrode) , temperature may be
changing rapidly or electrode may be thermally shocked (allow electrode to reach sample
temperature), sample may be non-aqueous (take 30 second readings and soak in pH buffer for
one minute between measurements)
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REPLACEMENTS & ACCESSORIES
Catalog No. Description
EC-BU-1BT
EC-BU-4BT
EC-BU-7BT
EC-BU-9BT
EC-BU-10BT
EC-BU-12BT
EC-DPC-BT
ECRE006
EC-BU-4BTC1LIT
EC-BU-7BTC1LIT
EC-BU-10BTC1LIT
EC-BU-4BS
EC-BU-7BS
EC-BU-10BS
EC-RIN-WT
pH 1.68 Buffer Solution, 480 mL
pH 4.01 Buffer Solution, 480 mL
pH 7.00 Buffer Solution, 480 mL
pH 9.00 Buffer Solution, 480 mL
pH 10.01 Buffer Solution, 480 mL
pH 12.45 Buffer Solution, 480 mL
Protein Cleaning Solution for pH electrode
Storage Solution for pH electrode
pH 4.01 Buffer Solution (Red), 1 L
pH 7.00 Buffer Solution (Yellow), 1 L
pH 10.01 Buffer Solution (Blue), 1 L
pH 4.01 Buffer Sachets, (NIST traceable)
pH 7.00 Buffer Sachets, (NIST traceable)
pH 10.01 Buffer Sachets, (NIST traceable)
pH Deionized Water Rinse Sachets (NIST traceable)
Detachment of storage bottl e for measurement
Attachment of storage bottle for storing elect rode
Step 1 Step 2 Step 2Step 1
(for covering filling hole)
Ring
Storage bottle c a p, with
rubber gasket
Storage bottle
(with solution inside)
Step 1: K eep the ring close.
Unscrew the stora ge bottle cap and remove the bottle.
Next, remove the cap with the rubber gasket.
Step 2: Rotate the ring and open the filling hole.
Start your measurement.
Step 1: Keep the fil l hole open.
Mount the cap with the rubber gasket.
Next, attach the storage bottle, electrode close to the base of the bottle.
Screw the storage bottle onto the cap tightly.
Step 2: Rotate the ring to close the filling hole.
Store your electrode.
Figure 1: Proper attachment and detachment of storage bottle to prevent electrolyte leakage
WARRANTY
This electrode is supplied with a six-month warranty against significant deviations in material and
workmanship.
Exclusions
The warranty on your instrument shall not apply to defects resulting from:
Improper or inadequate maintenance by customer
Unauthorised modification or misuse
Operation outside of the environment specifications of the products
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RETURN POLICY
Please obtain authorisation from our Customer Service Department or authorised distributor before
returning items for any reason. A “Return Goods Authorisation” (RGA) form is available through our
authorised distributor. Please include data regarding the reason the items are to be returned. Items
must be carefully packed to prevent damage in shipment and insured against possible damage or loss.
Eutech Instruments/ Oakton Instruments will not be held responsible for damage resulting from careless
or insufficient packing. A restocking charge will be made on all unauthorised returns.
NOTE: Eutech Instruments Pte Ltd reserves the right to make improvements in design, construction, and
appearance of products without notice.
As of the date of preparation of this document, the foregoing information is believed to be accurate.
However, no warranty or representation with respect to such information is intended or given.
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