pH Meter

A pH meter is an analytical instrument used to measure the activity of hydrogen ions in a solution which is then expressed as pH. Measuring pH is a widely applied analytical technique in various fields and ranges from laboratory measurements to process applications. With our pH meters, one can also measure other important parameters like Conductivity, Ion Concentration, ORP, and Dissolved Oxygen. This page shows the types of laboratory pH meters and their applications.

There are mainly two techniques to measure pH: pH indicators and pH meters. However, not all of them provide the same accuracy and quality level. A comparison between two widely used methods is shown below:

pH indicators

• Despite using pH indicators is a well-established analytical technique, it relies on paper or a soluble compound that changes the color with changing pH
• Although the indicator is an extremely simple tool, it cannot be used when higher accuracy is required (error ≥ 0.5 pH)
• Since the technique also relies on the visual comparison of colors, it cannot be used for measuring the pH of colored samples
• Fast technique

pH meters

• Can be used for both colored and colorless samples
• Provide highly accurate results (error ≥ 0.05 pH) within a short span of time
• The pH reading appears on the screen, therefore there is no need to guess or interpret the reading
• Yield quick results and are simple to operate

A pH meter measures the potential differences between a reference electrode (like Ag/AgCl) and a pH electrode (glass electrode). This difference between the two electrodes is related to the concentration of H⁺ ions in the solution. Therefore, the difference in potential corresponds to the acidity / pH of the solution.

pH meters are used for a variety of applications across many sectors such as:

• Agriculture: Measuring the pH of soil, fertilizers, pH of fruits and vegetables, grains, etc.
• Food and beverages: Quality control laboratories of various food and beverages like sauce, jams jellies, juices, milk, yogurt, cheese and other dairy products, fish, meat, soft-drinks, wine and other alcoholic beverages
• Water analysis: Testing the quality of pure water, portable water from municipal water supplies, swimming pools, effluents, environmental remediation, etc. natural water, waste water
• Healthcare and pharmaceutical: Testing of drugs, liquid syrups, and other clinical applications such as blood chemistry and all body liquids, testing of raw materials, testing of WFI (water for injections), pure water for pharmaceutical use, etc.
• Paints and dyestuff industry: pH becomes an important parameter in the case of paints to impart the desired properties to them to the final product. Eg: the pH of emulsion paints is maintained between 8.5-9.0 to avoid corrosion. If the pH of acrylic paints drops below 7.5, the paint gains a cheesy consistency and is ruined
• Cosmetics, flavors and fragrances: During manufacturing, pH is measured to monitor a product's consistency and quality., pH of final products, shampoo, face creams, serums
• Electroplating industry: pH is an important criteria and decides the quality and consistency of the plating. In addition, the pH measurement of pure water is important to ensure the right pH of the electrolytic bath

The choice of pH meter largely depends upon the type of application (laboratory or field). Based on the application and its needs, the meters are classified as:

1. Benchtop meters: pH meters designed specifically for laboratory use and meant for pH measurements in stationary applications for QC and R&D lab.
2. Portable meters: These are small, handheld, light weight pH meters, which can be carried to different locations like at-line measurements during manufacturing processes or outdoor / field applications.

Yes, we have pH meters that are specially designed to meet most strict compliance needs with LabX^® PC software.

Yes, we offer professional installation packages, qualification and calibration services. These services will guarantee accurate and precise measurements making the user worry-free when it comes to possible compliance issues during quality audits.

Yes, calibration helps in determining that the instrument is functioning correctly. Calibration is necessary to adjust the slope and offset an electrode to their true values for the measuring system in question. With routine calibration of the pH meter, ion meter, DO meter and conductivity meters, one can confidently conduct their measurements.

pH meters are calibrated with appropriate laboratory calibration solutions of known pH.  The frequency of calibration depends upon the frequency of the usage of the meter and applications. Nevertheless, one calibration day is recommended. For details please refer to the following calibration video.

This depends on the application. Dedicated single channel meters are used to measure one parameter at a given instance like:

a. pH
b. ORP
c. Ion concentration
d. Conductivity
e. Dissolved oxygen

Whereas multi-parameter instruments allow the measurement of more than one parameter at the same time.

A conductivity meter measures the conductivity or amount of electrical conductance of a solution. The higher the conductivity, the better the ability to pass a current through the solution. Conductivity is an important parameter and has several applications in water analysis, food and beverage, electronics and pharmaceutical industries.

Yes, our instruments support 13 languages. This makes selecting the right settings from the menu intuitive because the instrument speaks your language. Currently, our instruments support English, German, French, Spanish, Portuguese, Italian, Russian, Chinese, Japanese, Korean, Polish, Thai and Turkish languages.

We offer benchtop meters that are built to last by withstanding spills on the housing and connections. This provides protection while allowing for easy cleaning with a damp cloth (IP54 protection). Similarly, our portable meters are completely waterproof and made to withstand harsh and demanding field applications (IP67 protection).

Indeed, we have meters, which support the printing of results in 3 different formats or even customized reports (or printouts) and other information to compact printers such as the RS-P25 or USB-P25.

Yes, we have pH meters that support automation. This is a good option for increasing productivity and efficiency in your lab. For further details, please click here.

The METTLER TOLEDO pH Competence and Support Center (pH CSC) comprises of a team of experts in direct electrochemical analysis. Due to the team's close contact with customers, technical support, product management and product development, quick advice and effective solutions can be provided, making this service rather unique in the world of pH analysis.

The offered technical and applicative support encompasses the following measuring parameters and the related METTLER TOLEDO pH Lab equipment:

• pH
• Redox (ORP)
• Ion concentration (ISE)
• Conductivity
• Dissolved oxygen (DO)

The following accessories can be used along with the pH meter to improve its function

• Electrode arm (included with most bench meter kits)
• Magnetic stirrer
• Printer
• Barcode reader
• EasyDirect™ pH
• Fingerprint reader (for the SevenExcellence pH meter)