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The everyday LabSen. Refillable, fast and TRIS-ready.
APERA INSTRUMENTS / LABSEN 211 · 213 / AI3101 / AI3121
LabSen 211 and 213 are Apera’s general-purpose refillable glass pH electrodes for professional lab and field measurement of general water solutions, and they are compatible with TRIS buffers. The 211 is a combination pH electrode with a BNC connector; the 213 adds a built-in temperature sensor with an RCA plug for automatic temperature compensation.
It reads pH 0 to 14 from 0 to 100°C. Choose the version that matches your meter’s connector from the menu above. Apera warrants LabSen electrodes for six months from delivery.
Only published products are linked. Other cards provide model-comparison information and do not indicate current storefront availability.
Start with your sample. Each card opens an electrode family; on that page, pick BNC, BNC/RCA pH/temperature or 8-pin to match your meter.
AI3101 / AI3121
General water, TRIS buffers
Refillable everyday glass electrode; BNC or BNC/RCA pH/temp.
AI3102 / AI3123
Titration, low ionic strength
Movable sleeve junction: easy to clean, adjustable flow.
AI3111
Wastewater, suspensions
Glass body, open junction and polymer electrolyte.
AI3131 / AI3133 / AI3231
Wastewater, harsh environments
Corrosion-resistant POM body, open junction; BNC, BNC/RCA or 8-pin.
AI3107 / AI3172
Skin, textiles, paper, leather
Flat glass membrane and PTFE ring junction.
AI3108 / AI3137 / AI3233
Pure, DI and RO water
L-type low-resistance glass (<50 MΩ) for low-ionic water.
AI3149
Cold samples to −25°C
L-type conical glass and Protelyte for −25 to 80°C.
BNC versions plug into any pH meter with a BNC input. They have no temperature sensor, so pair them with a separate temperature probe such as Apera’s MP500 where compatible with the meter, for automatic temperature compensation; manual temperature entry is an option only if the meter supports it at the sample temperature. Electrode ratings do not extend the meter’s or separate temperature probe’s operating or compensation limits.
BNC/RCA versions carry a built-in 30 kΩ NTC temperature sensor on an RCA plug for automatic temperature compensation on Apera meters with BNC and RCA inputs, such as the PH700, PH850, PH8500, PH820, PH910 and PH9500. Apera notes they may not work with other brands’ meters because the thermistor might not be compatible.
Low resistance for fast response and high firmness. Apera says readings fully stabilize in 15–30 seconds and the membrane is 10 times stronger than traditional glass.
A glass-tube Ag/AgCl reference with silver wire improves stability and extends service life. Ceramic junction, 3M KCl electrolyte, refillable.
Apera’s Swiss blue gel keeps air bubbles out of the glass membrane.
All versions share: pH range 0–14; temperature range 0–100°C; body lead-free glass; glass membrane S-type, hemispherical; junction ceramic; reference electrolyte 3M KCl.
The full specification table is in the Product Specifications tab.
Keep the tip in its cap with 3M KCl storage solution whenever it is not measuring.
Never store a pH electrode in pure, deionized or distilled water.
The 211 and 213 are refillable: keep the fill hole open while measuring and top up the reference electrolyte when the level drops.
Rinse with distilled or deionized water between samples. For stubborn deposits, use Apera electrode cleaning solution, then recondition and recalibrate.
Apera ships this electrode in these kits: PH950 (LabSen 211), PH9500 (LabSen 211), PH8500-BR (LabSen 213), PH850-BR (LabSen 213).
Calibrate with fresh pH 7.00, pH 4.00 and pH 10.01 buffers.
LabSen 211 and 213 are Apera’s general-purpose refillable glass pH electrodes for professional lab and field measurement of general water solutions, and they are compatible with TRIS buffers.
Choose LabSen 211 (AI3101; BTS-AI3101) for BNC pH measurement without a built-in temperature sensor, or LabSen 213 (AI3121; BTS-AI3121) for BNC/RCA pH and a 30 kΩ NTC sensor on a compatible Apera meter.
The pH signal is standard BNC, but Apera notes the temperature thermistor may not be compatible with other brands’ meters. Use it on Apera meters with BNC and RCA inputs.
Yes. Both LabSen 211 and 213 use 3M KCl reference electrolyte. Keep the fill hole open during measurement and refill when the level drops.
Keep the tip in its cap with 3M KCl storage solution whenever it is not measuring. Never use pure, deionized or distilled water.
Both are offered to the current US specifications: pH 0–14 and 0–100°C. Check the meter and temperature-compensation limits separately; a matching connector does not expand them.
Use fresh pH buffers and follow the meter’s calibration procedure. The electrode manuals call for at least a two-point calibration before measuring with a new electrode; rinse between buffers and samples.
Apera warrants LabSen electrodes against defects in material and workmanship for six months from delivery. Accidental damage, improper use and normal wear are excluded.
Check the version, connector and catalog number (AI3101 / AI3121) against your meter and samples, then return to the live price and ordering controls.
APERA INSTRUMENTS, LLC warrants LabSen electrodes to be free from defects in material and workmanship for SIX MONTHS from the delivery.
This limited warranty does NOT cover accidental damage, improper use, normal wear and tear, transportation, storage, failure to follow the product instructions, unauthorized maintenance, modification or repair, or external causes beyond Apera's reasonable control.
Official Apera PDF documents, with model and regional scope stated on each card. Each whole card opens its PDF in a new tab.
Document scope and limits. These are separately labeled exact-model manuals, not a universal connector guide. This offer retains the current US 0–100°C specification; the 213 manual lists a −5°C lower limit. The 213 PDF contains a manufacturer 211 model-name typo in its body text; its title and temperature-sensor specifications identify 213.
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