Intellical Red-ROD technology High performance pH probes for HQd-series

IntelliCal pH Red-Rod sensors portfolio PHC705 PHC705A PHC725 PHC735 Diaphragm Types & Flow rates Porous pin Annular ring Sleeve Porous pin, A = Alkaline Annular Ring, PHC735 = High Flow 50 µL/h 120 µL/h 1 mL/h ~10 µL/h PHC729 PHC745 flat, surface ring diaphragm Sleeve junction with Adjustable high flow

IntelliCal Red-Rod Applications Common features: Glass Body Red Rod Saturated KCl reference Refillable reference element Temperature range: From -10°C to 100°C pH Range: from 0 to 14 pH Model Type Applications Junction Types PHC705 General Purposes Porous Pin PHC705A High-alkalinity media PHC725 General Purposes & Low Ionic Strength media Annular Ring PHC735 Dirty Samples (eg. Untreated Surface Waters) Annular Ring (High Flow) PHC745 Challenging Samples (eg. Wastewater influent, Emulsions) Reverse Sleeve (High Flow, Fast cleaning) PHC729 Surface Measurements Flat Annular Ring

comparison of “Standard” vs. “Red-Rod”

Red-rod vs Light influence Red tubes inside the probe Looking at a Red-Rod pH probe, the first visible difference from “standard” pH probes is the two inner red glass tubes. What is their purpose? The standard reference system comprises a combination of silver wire (Ag) and silver chloride (AgCl) in equilibrium: AgCl  Ag+ + Cl-, The status of the equilibrium depends on AgCl, Silver and Chloride ions. If one side of the reaction changes, the equilibrium changes as well. Therefore the reference element is no longer stable, identified by a changing reference potential and a shorter lifetime. Ambient light, especially the daylight, reacts continuously with AgCl and reduces traces of silver ion to silver metal. This reduces the lifetime of the probe.   AgCl + [UV or blue light]  2 Ag + Cl2  Red colored glass tubes protect the reference system eliminating the effect of UV or blue light thus ensuring the reference systems remains stable over a long period of time.

Red-rod vs Temperature variations The filling solution of standard pH probes is non saturated 3 molar KCl, it does not provide any indication to the operator of possible variations in refill electrolyte solution impacting reference element mV response due to of dilution or clogging crystallization. Red-Rod Saturated KCl filling solution allows visual control of suspended crystals giving a clear indicator to operators that solution remains saturated, ensure stable saturated KCl concentration and a stable reference potential with temperature increase. Red-Rod pH sensors contain additional KCl crystals in pH bulb and in reference element “buffering” KCl solubility changes with temperature to ensure reference filling electrolytes stability through temperature variations up to 100°C! Special KCl crystals for Red Rod prevent (re)crystallization clogging of the junction ensuring KCl crystals keep moving freely. Red Rod saturated KCl ensures visual control at glance and reference systems mV reading stability over temperature variations.

Red-rod vs Reading stability Symmetrical Reference System Usually a combined pH probe reference system consists in a Ag/AgCl/KCl system in both elements, Reference & Indicating. Standard pH probes are usually mounted with a basic Ag wire coated with AgCl immersed directly in the KCl electrolyte solution. Such “wire” design cannot ensure both Ag/AgCl reference elements match equally from the start and over the electrode usage period, thus creating an asymmetric geometry causing an Asymmetry Potential difference from an ideal zero mV. Red-Rod technology design assembly ensures a perfect symmetry in construction offering a quasi-perfect potential reading which is stable over time. Red-Rod Standard Red Rod Symmetrical System ensures stability of reference systems mV reading over time. Coated silver wire only

Red-rod: Reading stability mV measured in buffer 4.01 mV difference after one year mV measured in buffer 7.00 mV difference after one year mV measured in buffer 10.01 Red-Rod pH probes demonstrate perfect mV reading stability

Red-rod : Response Time Red-Rod pH probes symmetric reference design ensures faster stabilization time and more accurate reading, especially in cold buffers. 15 vs. 90 sec. response time

Red-rod benefits Red Rod encapsulated reference and indicating elements prevent silver ion diffusion.  Dramatically reduce the risk of contamination and junction reference clogging.  Ensure mV reading accuracy and extended probe lifetime Red tubes protect from UV light degradation over time.  Symmetrical Red Rod reference elements reduce asymmetry potential Ensure mV reading stability over time.  Saturated KCl solution with KCl crystals Determine electrolyte status at a glance

Red-rod benefits Additional KCl crystals maintaining saturation of the reference electrolyte at higher temperatures  Stable reference system for best pH results up to 100°C Glass probe body withstands heat and organic chemicals  Enlarging the application range to difficult matrices and use models Probes with various designs and diaphragms (liquid junctions)  Higher flexibility in selecting the best pH probe for your sample pH measurement  Combining both technologies for reliable results and highest comfort Red-Rod pH probes now with digital technology