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How a Calibration-Free, Dry-Storable pH Meter Works

pH, one of the most fundamental properties in all of nature, is measured in nearly every industry including general laboratory research, pharmaceuticals, food and beverage processing, environmental testing and agriculture. Despite the importance of measuring pH, traditional glass pH meters have long suffered from problems associated with calibration and maintenance.

by Senova Systems
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Problem: Accurate pH measurement requires well-trained technicians to spend hours calibrating and maintaining pH electrodes, resulting in extra manpower and material costs. Complex maintenance and calibration protocols increase the possibility of human error and technical issues. The threat of contamination from broken glass electrodes often forces industrial process control users into labor-intensive and suboptimal off-line pH measurements. In addition, miscalibration and signal drift can ruin products and experiments. Unless users follow the tedious use protocols, pH electrodes are subject to breakage. Critical elements can also dry out or clog, rendering the instrument inaccurate or nonfunctional. These issues are common to virtually every pH meter in use today.

Solution: The new calibration-free pHit handheld pH scanner from Senova Systems is based on innovative technology that eliminates the frequent problems of conventional pH meters.

Senova Systems pH ScannerThe pHit sensor contains analyte sensing molecules (ASMs) covalently attached to a carbon substrate. The pHit Scanner applies a voltage scan across the sensor, causing the ASMs to gain or lose electrons. The voltage at which this reaction occurs correlates to a specific pH.At the heart of the pHit scanner is its novel solid-state sensor technology. The pHit sensor, composed of carbon substrate, contains covalently attached analyte sensing molecules (ASMs). These ASMs are reduction-oxidationactive compounds which, when subjected to a voltage sweep or scan, reversibly bind hydronium ions. The pHit sensor works by applying a voltage scan across the sensor, causing the ASMs to gain or lose electrons. The voltage at which this redox reaction occurs is dependent on the concentration of hydrogen ions in the sample (pH). If there is a high concentration of hydrogen ions present (low pH), the redox reaction occurs at a lower voltage. If there is a low concentration of hydrogen ions present (high pH), the reaction occurs at a higher voltage. The relationship between the voltage at which the reaction occurs and pH is constant and reproducible. This relationship or algorithm is stored internally in the firmware, rendering user-calibration unnecessary. The scanner processes the sensor’s signal to produce and display the pH of the sample being analyzed.

The pHit scanner is one option that minimizes the risk of miscalibration that can result in ruined experiments, damaged product and wasted time. The instrument is more than just calibration-free; it is almost maintenance-free and nearly indestructible. The solid-state sensor and stainless steel body increase durability, and the threat of drying and clogged elements is eliminated because the sensor is composed of carbon and can be stored dry.

For the user, products such as the pHit handheld scanner allow time and energy to be devoted to more important tasks. For the lab manager, they offer a significantly lower cost of ownership by reducing manpower requirements and by eliminating calibration buffers, storage solutions and the frequent replacement of glass electrodes. The pHit Scanner does this while producing results with accuracy and precision that are comparable to the highest priced conventional pH meters on the market today.

For more information on the pHit handheld scanner, please visit