WTW digital IDS pH microelectrode SenTix Micro 900, Ø 5 mm, 1.5 m fixed cable, 103751

Where a 12 mm electrode does not fit into the vessel, a tapered shaft helps: the WTW SenTix Micro 900 has a glass shaft that narrows to a diameter of 5 mm. It is a digital IDS electrode with a platinum wire junction and a refillable liquid electrolyte (KCl 3 mol/l, Ag+-free). The sensor data including calibration are stored in the head. The measuring range is 0 to 14 pH, and the sample temperature may be 0 to 100 °C.

Typical applications according to WTW

WTW names small sample volumes and measurements in vials, as well as saliva. In addition there are enzyme solutions, gastric juice, infusion solutions, protein-containing liquids, serum, Tris buffer solutions and urine, which WTW lists under pharma, biology and medicine. This classification is not a statement on suitability for medical devices.

Stepped shaft with 5 mm membrane

WTW gives the shaft length as 65/130 mm and the diameter as 12/5 mm. The membrane is cylindrical and 5 mm wide. According to WTW, the platinum wire junction ensures optimum electrolyte flow without clogging. According to the product page, the membrane resistance is below 700 MΩ. An NTC temperature sensor (30 kΩ) is built in; according to WTW, the IDS electronics measure with pH ±0.004, ±0.2 mV, ±0.1 °C (±1 digit in each case).

Connection

The SenTix Micro 900 has a permanently attached 1.5 m cable with a waterproof IDS plug (4-pin, lockable). The cable is 4.3 mm thick; according to WTW, the smallest permissible bending radius is 20 mm for fixed installation and 60 mm in flexible use.

Refilling, storage and care

The electrode is filled at the factory, and the refill opening stays open during calibration and measurement. If the level drops, reference electrolyte is topped up with the dropper bottle, which is included according to the WTW instructions. In narrow vessels, the membrane should not touch the bottom, so that it does not get scratched. Between measurements, the electrode stands in reference electrolyte with the opening open, and overnight in the wetting cap filled with it, with the opening closed. If stored dry or in deionised water, it can be permanently damaged. According to WTW, salt deposits on the cap do not affect the measurement. According to WTW, protein deposits are removed with about one hour in pepsin cleaning solution PEP/pH.

Technical details

Scope of delivery

• 1 WTW SenTix Micro 900 pH electrode with wetting cap
• Dropper bottle for refilling (included according to the WTW instructions)
• Operating instructions
• Fixed cable 1.5 m with IDS plug, permanently attached to the electrode

Regulatory information

As an electrical device, the digital IDS electrode falls under the ElektroG. The manufacturer Xylem Analytics Germany GmbH (WTW brand) is registered under the WEEE registration number DE 29884659. How to return old appliances is described on the page Environment and disposal.

Accessories and procurement service

Also available are reference electrolyte KCl 3 mol/l for refilling, pepsin cleaning solution PEP/pH and buffer solutions for calibration. For further micro and special electrodes from WTW, there is the procurement service.