A pH meter measures the acidity or alkalinity of a liquid sample by reading the electrical potential a pH electrode generates when it contacts the solution, giving pharmaceutical manufacturing, quality control, and research work a fast, precise reading that litmus paper or a colour-change indicator could never match.

Pharmaceutical manufacturers and laboratories rely on this equipment because pH sits behind so much of what determines a formulation's stability, a process's success, and a product's compliance with specification, and getting that single number wrong can throw off everything downstream of it. Browse new and used pH meters and sensors from verified sellers on Machinery Masters.

What Are pH Meters & Sensors?

A pH meter pairs a pH electrode with a display and processing unit that converts the electrode's electrical signal into a readable pH value, and the electrode itself does the real measurement work. A combination pH electrode, often simply called a pH probe, houses both the measuring and reference elements in a single unit, the standard configuration for most laboratory and process applications, while specialised probe designs handle non-standard samples such as viscous liquids, small volumes, or surfaces that a conventional pH probe can't reach into properly.

Benchtop pH meters offer the higher accuracy, multi-point calibration, and data logging capability that routine laboratory quality control work demands, while portable pH meters trade some of that precision for the ability to take a reading anywhere in a facility rather than bringing a sample back to a fixed instrument. ORP, or oxidation-reduction potential, meters measure a related but distinct electrochemical property, often built into the same instrument as a pH meter since both readings frequently matter together in water treatment, cleaning validation, and certain manufacturing processes.

None of these readings mean anything without regular calibration against certified pH buffer solutions, since an electrode's response drifts over time and use, and a meter is only as accurate as its most recent calibration.

pH Meter & Sensor Brands

Mettler-Toledo, known for its benchtop pH meter ranges and InLab electrode line
Thermo Fisher Scientific, known for its Orion Star series pH meters and electrodes
Hach (a Veralto company), known for its pH and water quality meters
Hanna Instruments, known for its benchtop and portable pH meter ranges
Sartorius, known for its PB-11 basic pH meter
Metrohm, known for its pH and titration instrumentation
Xylem, known for its YSI brand multiparameter meters that include pH measurement

Please verify this brand list against current Machinery Masters marketplace inventory before publishing, as available stock changes over time.

pH Meter & Sensor Product Types

pH meters and sensors divide into a handful of formats depending on where the measurement happens and what additional parameters they need to capture alongside pH.

Benchtop pH Meters

Benchtop pH meters offer higher accuracy, multi-point calibration, and data logging capability suited to routine laboratory quality control work, sitting at a fixed station rather than moving around a facility with the user.

Portable pH Meters

Portable pH meters trade some benchtop precision for the ability to take a reading anywhere in a facility, suiting at-line process monitoring and field sampling, where bringing a sample back to a fixed instrument would introduce delay.

pH Electrodes and Probes

pH electrodes and pH probes do the actual measurement work, with combination probes housing both measuring and reference elements in a single unit for most standard applications and specialised designs available for viscous samples, small volumes, or surface measurement.

ORP Meters and Combination Instruments

ORP meters measure oxidation-reduction potential, a related electrochemical property often built into the same instrument as a pH meter since both readings frequently matter together in water treatment and certain manufacturing processes.

Calibration Buffers and Solutions

Certified pH calibration buffer solutions provide the known reference points a pH meter and electrode get calibrated against, with regular calibration essential since an electrode's response drifts over time and use.

pH Meter & Sensor Applications and Uses

pH meters and sensors support formulation stability, process control, and quality assurance across pharmaceutical manufacturing and laboratory operations.

Formulation Development and Stability Testing

Pharmaceutical formulation work relies on accurate pH measurement to develop stable products, since many active ingredients and excipients only remain stable and effective within a specific pH range.

In-Process Manufacturing Control

Manufacturing processes monitor pH in real time to confirm a reaction, fermentation, or purification step is proceeding within its validated parameters, catching a deviation before it affects the final product.

Quality Control and Batch Release Testing

Quality control laboratories measure pH as part of routine batch release testing, with calibration traceability and documented electrode maintenance forming part of the regulatory record each result needs to support.

Cleaning Validation and Water Quality Monitoring

Cleaning validation programmes and water for injection or purified water systems rely on pH and ORP measurement to confirm cleaning processes and water quality meet their specified parameters.

Research and Bioprocess Development

Research and bioprocess development teams use pH measurement throughout cell culture, fermentation, and purification work, where maintaining pH within a narrow range often determines whether a biological process succeeds.

How to Choose a pH Meter

A handful of practical factors determine which pH meter or sensor suits a laboratory or manufacturing operation.

Match benchtop or portable format to where the measurement needs to happen, choosing benchtop for fixed-station laboratory work and portable for at-line or field sampling.
Confirm electrode type suits your sample, since viscous liquids, small volumes, or surface measurements often need a specialised electrode rather than a standard combination electrode.
Check whether ORP measurement capability is needed alongside pH for your specific application, such as water treatment or certain cleaning validation processes.
Consider data logging and audit trail capability if the meter needs to support regulated quality control documentation.
For used equipment, request full calibration history, confirm electrode condition and remaining service life, and verify accuracy against certified buffer solutions before relying on the equipment for regulated use.

Frequently Asked Questions

How often should a pH meter be calibrated?

A pH meter should be calibrated before each use in a regulated application and, at minimum, daily in routine laboratory settings, using certified buffer solutions that bracket the expected sample pH range. Electrode response drifts over time and with use, so a meter is only as accurate as its most recent calibration.

What is the difference between a benchtop and a portable pH meter?

A benchtop pH meter offers higher accuracy, multi-point calibration, and data logging capability suited to routine laboratory quality control work, while a portable pH meter trades some of that precision for the ability to take a reading anywhere in a facility. Laboratories doing fixed-station QC work generally need benchtop accuracy, while field or at-line sampling favours the portable format.

Why does a pH electrode need regular maintenance?

A pH electrode needs regular maintenance because its glass membrane and reference junction gradually degrade with use, causing slower response times and less accurate readings even when the meter itself is functioning correctly. Proper storage in electrode storage solution and periodic cleaning extend an electrode's usable life and keep calibration results reliable.

What is the difference between new and used pH meters and sensors?

New pH meters and electrodes come with a manufacturer warranty and current calibration certification, while used equipment offers meaningful cost savings and suits organisations that can confirm calibration history and check electrode condition. It is worth verifying accuracy against certified buffer solutions before relying on used equipment for regulated production.

How can I find pH meters and sensors on Machinery Masters?

Browse the Machinery Masters marketplace for new and used pH meters and sensors from verified sellers, and use the filters to narrow results by brand, format, and application. Contact a seller directly to confirm specifications, service history, and pricing before you buy.