WTW SenTix 81 analogue precision pH electrode, glass shaft, 103642

The WTW SenTix 81 analogue precision pH electrode represents a premium-class metrological system solution for high-precision and reliable pH measurement in demanding laboratory applications. Designed for use with classic analogue pH meters from the WTW inoLab and Profiline series, this high-quality glass electrode offers excellent signal transmission and the highest measurement accuracy. For complex tasks in chemical research, pharmaceutical quality control or university-level analysis, rapid and stable potential stabilisation is the primary criterion for ensuring reproducible measurement results in a process-reliable manner that minimises damage to the sample.

Traditional analogue technology and integrated temperature compensation

The mechatronic system architecture of the SenTix 81 is based on reliable, analogue signal transmission. The measured potential is transmitted via a high-quality, shielded fixed cable directly to the analogue input stage of the pH meter. A key functional feature is the 30 kOhm NTC temperature sensor integrated into the sensor head. This sensor measures the sample temperature simultaneously with the pH value, enabling the connected meter to perform automatic temperature compensation in real time. This reliably eliminates thermodynamically induced measurement errors caused by fluctuating ambient temperatures, without the need to immerse a separate temperature sensor in the sample.

High-quality platinum diaphragm and refillable reference system

The materials-science-based design is uncompromisingly optimised for maximum precision and fast response times. The electrode features a chemically highly resistant glass shaft and a cylindrical glass diaphragm. A tried-and-tested liquid electrolyte (3 mol/l KCl) serves as the reference system; this can be easily topped up or completely replaced via a sealable opening at the top of the glass shaft. A standout technological feature is the integrated platinum diaphragm. This specialised diaphragm ensures a continuous and uniform flow of electrolyte without the risk of blockages, even with challenging sample media such as emulsions, suspensions or slightly viscous solutions.

Universal connectivity and ergonomic laboratory use

To ensure seamless integration into laboratory set-ups, the SenTix 81 features a permanently attached, 1-metre-long cable terminated in tried-and-tested standard connectors. The pH channel is connected via a standard DIN plug, whilst the integrated temperature sensor is connected via a 4 mm banana plug. This standardised plug combination guarantees universal compatibility with a wide range of analogue measuring stations on the market. The flexible cable ensures optimal ergonomic movement and allows fatigue-free working when sequentially measuring larger sample series directly at the workstation.

Technical Details

Measurement & Sensor Technology

• Sensor type: Analogue pH combination electrode
• Model: SenTix 81
• pH measurement range: 0 to 14 pH
• Temperature element: Integrated NTC 30 kOhm temperature sensor
• Operating temperature range: 0 to 100 °C

Construction & dimensions

• Shaft material: Highly chemically resistant glass shaft
• Electrolyte: Liquid electrolyte (3 mol/l KCl, refillable)
• Diaphragm: High-quality platinum diaphragm
• Shaft length: 120 mm
• Shaft diameter: 12 mm
• Connection type: Fixed cable, length 1.0 m
• Connector combination: Waterproof DIN plug (for pH) and 4 mm banana plug (for temperature)

Operating conditions

• Maintenance: Refillable (KCl solution replaceable)
• Main applications: Demanding laboratory measurements, chemical analysis, challenging sample media, general aqueous media

Contents

• 1 x WTW SenTix 81 analogue pH glass electrode with 1 m fixed cable (MPN: 103642)
• 1 x storage cap with original storage solution
• 1 x pipette bottle with refill electrolyte (3 mol/l KCl)
• 1 x Quick start guide / Quality certificate

Important note: pH buffer solutions for regular calibration and the analogue pH meter itself are not included as standard and must be ordered separately.

Individual requirements & accessories

To ensure consistently high measurement accuracy of the WTW SenTix 81, regular recalibration of the measuring station is essential. For this purpose, our range includes certified WTW technical buffer solutions in practical dosing bottles (pH 4.01, pH 7.00 and pH 10.01). For the proper care and storage of the pH-sensitive glass membrane during measurement breaks, we strongly recommend the use of the original 3 mol/l KCl storage solution. Should the electrode ever become contaminated with stubborn sample residues during the rigours of everyday laboratory work, we offer special cleaning concentrates for gentle regeneration. Please make use of our technical procurement service when putting together your laboratory equipment.