Routine and reliable pH measurements

Routine and reliable pH measurements

pH measurement is often a critical early step in your workflow. We offer an extensive line of pH meters, pH electrodes, pH buffers, and pH measurement accessories designed to work seamlessly together to make your complex pH measurements routine and reliable.

Measure with confidence with products you trust, like Orion and ROSS electrodes.

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What is pH and why should it be measured?

pH compares the acidity or alkalinity of a solution at a given temperature. A pH of 7 describes a neutral solution because the activities of hydrogen and hydroxide ions are equal. When the pH is below 7, the solution is described as acidic—the hydrogen ion activity increases and the pH value decreases. When the pH is above 7, the solution is described as basic (or alkaline)—the activity of hydroxide ion is greater than that of hydrogen ion.

pH electrode measurements are made by comparing the readings in a sample with the readings in standards whose pH has been defined (buffers). Thermo Scientific pH meters contain pH versus temperature values for commonly used buffers. This allows the meter to recognize a particular pH buffer and calibrate with the correct buffer value at the measured temperature.

Download pH Handbook

Thermo Scientific pH measurement products and solutions

Tackle your specific sample analysis challenges head on with our rich portfolio of meters, electrodes, and solutions. High-quality meters are essential to the critical, routine tasks you perform every day. Our portfolio of benchtop and portable meters are designed to help you meet your sample analysis challenges across a wide array of industries and applications. We offer simple, complete systems that are seamlessly integrated to help address your measurement needs.

Our meters, electrodes, buffers, standards, and solutions are designed for a number of applications and industries:

  • General laboratory testing
  • R&D
  • Government compliance
  • Pharmaceutical
  • Power generation
  • Drinking water
  • Wastewater treatment
  • Food & beverage testing
  • Environment
  • General industrial processing

Benchtop pH Meters

Benchtop pH measurement

The ideal choice for dedicated pH testing in water, process, research, and QA/QC samples. The Thermo Scientific portfolio of pH Meters offer a range from simple & economical models to powerful & sophisticated pH meters, to help you analyze your samples with confidence.

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Portable pH Meters

Portable pH measurement

Our portable pH meters are designed to offer pH testing in the field for applications including environmental, drinking water, and wastewater analysis.

 

 

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Electrodes and Probes 

Electrodes for pH measurement

An extensive assortment of quality pH electrodes and sensors are available in a variety of body materials, body styles, fill types, reference styles, and junctions to meet the needs of your sample measurements.

 

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Standards and Solutions

Standards and solutions for pH measurement

We offer pH buffers, pH electrode storage solutions, electrode cleaning solutions, lab buffer kits, and electrode filling solutions for your pH measurement needs. Our pH buffers are NIST-traceable with certificates of analysis available for each solution batch.

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The most common error in pH measurements

The most common cause of error in pH measurements is temperature. Temperature variations can influence pH for the following reasons:

  • The electrode slope will change with variations in temperature
  • Buffer and sample pH values will change with temperature
  • Measurement drift can occur when the internal elements of the pH and reference electrodes are reaching thermal equilibrium after a temperature change
  • When the pH electrode and temperature probe are placed into a sample that varies significantly in temperature, the measurements can drift because the temperature response of the pH electrode and temperature probe may not be similar, and the sample may not have a uniform temperature, so the pH electrode and temperature probe are responding to different environments

Electrode slope changes can be compensated for by using an automatic temperature compensation (ATC) probe or a Thermo Scientific Orion Triode electrode which has an ATC probe incorporated into the body of the electrode. Thermo Scientific pH meters calculate the electrode slope based on the measured temperature of the pH buffers. The meter will automatically adjust the pH buffer value to the actual pH of the buffer at the measured temperature.

The pH electrode should be calibrated with buffers that have known pH values at different temperatures. Since some pH meters without ATC are unable to correct sample pH values to a reference temperature, the calibration and measurements should be performed at the same temperature and sample pH values should be recorded with the sample temperature.

Orion pH Buffer Values vs. Temperature ›


Featured pH measurement videos

Measuring pH in drinking water using the Thermo Scientific Orion Versa Star Pro benchtop meter.

Calibrating a Thermo Scientific Orion Star A series pH benchtop meter.

 

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Knowledge Base: Certificates of Analysis and SDS for Orion, ROSS, AQUAfast, AquaMate, and AquaSensors products.

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