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Product Focus: pH Meters

The frequency of measuring might be one of the biggest trends in pH meters. “It used to be an occasional measurement, but now it’s every sample in some cases,” says George Porter, titration product manager at Metrohm (Riverview, FL).

Mike May, PhD

Mike May is a freelance writer and editor living in Texas.

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Making more measurements and automating collection and analysis

To make pH measurements on more samples, many users automate the process. “That just takes a sample changer with a pH instrument connected,” says Porter. “We have a few options there, including highthroughput sampling that measures several hundred samples in series.”

The automation also extends to data handling. “pH meters are catching up with other devices,” says Porter. That includes making the meters connect to a laboratory information management system (LIMS) or computer in general instead of writing down each result in a notebook. That takes a device with the right sort of connectivity and software support.

According to Mari Lynne Gentry, marketing manager at Mettler Toledo (Columbus, OH), “pH meters now measure more than just pH. With multiparameter meters, multiple measurements can be made, including conductivity, ion concentration, dissolved oxygen, biochemical oxygen demand, oxygen reduction potential, total dissolved solids, salinity, resistivity, and temperature.” She adds that even portable meters can now make multiple measurements.

Despite adding so many capabilities, today’s meters can be easier to use. For example, Gentry described Mettler Toledo’s One Click concept by saying, “With a single click, you can start a sequence of analysis steps with fixed preset parameters.”

Features to find

In the Department of Chemistry and Chemical Biology at McMaster University in Hamilton, Ontario, Canada, undergraduate technician Trisha Martin says, “I am part of the undergraduate program, and we look for meters that are easy to use without a lot of buttons, menus, or options.” She adds, “We also look for universal connections on the back so that we are not limited in the electrodes that we can buy, and the newer features of a USB to store the data are a nice feature for the students as they will have ‘backup’ data.” In the future, she’d like to see a pH meter with “an arm that can be stored easily.”

In the School of Chemistry at the University of New South Wales in Sydney, Australia, first-year laboratory coordinator Ron Haines looks for pH meters that provide a “large display, ease of use, and robust design, especially for the electrode.” He adds that he “would love to see a ‘student mode’ button that disables all other controls.”

Other users need different features. An as example, Porter says, “Look for a meter than offers flexibility with buffers, being able to use multiple kinds.” He adds, “Make sure the device has a buffer table with it.”

Gentry adds that a meter should provide good laboratory practice (GLP) “compliance, including user management, printing and data storage options, regulatory support,” and equipment qualification.

For the best return, scientists want flexibility. For that, says Porter, “Look at expandability.” He adds, “I was a lab manager for six years, and I always considered the ability to put a sample changer on a device.”

For additional resources on pH meters, including useful articles and a list of manufacturers, visit