In the lab and at the tap, water must be analyzed for safety and purity
There’s a lot of water out there—about 326 million trillion gallons on Earth, according to the Infrared Processing and Analysis Center at the California Institute of Technology—but there’s not as much clean water as there used to be. “In recent years, climate changes have stressed water resources,” says Giovanni De Dona, senior product manager, water and lab products, Thermo Fisher Scientific (Chelmsford, Mass.). “In addition, contaminated water sources in heavily industrialized areas have made clean drinking water a more valuable commodity.” These factors can increase the need to analyze water.
Our health depends on clean drinking water, and governments usually set up regulations that prevent contamination in water supplies. “With limited resources and funds, the result has been to drive measurement systems to lower costs, more features and higher performance,” De Dona explains.
Higher performance often includes a combination of speed and sensitivity, which can arise from the right mix of analytical devices. When trying to remove anions, “Ion chromatography—IC—and reagent-free IC systems with electrolytic eluent generation and electrolytic suppression have removed challenges and greatly improved sensitivity, ease of use, reproducibility and robustness,” says Richard Jack, senior director, environmental and industrial marketing, chromatography and mass spectrometry, Thermo Fisher Scientific (Waltham, Mass.). The company’s new Integrion IC system incorporates the latest developments for the analysis of anions and disinfection by-products in water, including reagent-free IC and high-pressure IC (HPIC), providing analysis up to 10 times faster than older-generation systems. “The recent combination of IC with mass spectrometry using single-, triple-quad and Orbitrap instruments has improved the sensitivity a thousand-fold for organic pesticides and disinfection by-products.” The Integrion and ICS-5000 dual HPIC system, coupled with the Q Exactive Orbitrap mass spectrometer, are state-of-the-art solutions for screening for unknown contaminants and for quantification, says Jack.
Softening the salts
Some drinking water is hard because of a high level of dissolved minerals, which depends on the local geology. The rocks that the water flows over and through and how soluble they are determine the level of hardness. “Many drinking waters arrive at the customer tap with over 200 milligrams per liter of dissolved salts—predominantly magnesium and calcium compounds,” says David Price, product specialist for PerkinElmer.
To measure toxic trace elements in water, scientists often use inductively coupled plasma-mass spectrometry (ICP-MS). “When testing drinking water, the analytical challenge is to ensure that the variable matrices do not create a bias in the sample results,” Price explains. “This is a possible risk as the amount of dissolved material in the sample affects the energy available to ionize the elements of interest in the argon plasma.”
Many water-testing laboratories once measured high-concentration elements—such as magnesium and calcium—with ICP-optical emission spectrometry and the trace elements—such as cadmium and lead—with ICP-MS. “Increasingly, laboratories recognize the time- and money-saving approach of using ICP-MS for all elements,” Price says.
The user-friendly NexION 2000 ICP-MS system from PerkinElmer is equipped with a coil that never needs to be cleaned or replaced. (Image courtesy of PerkinElmer.)
To help scientists apply these benefits, PerkinElmer developed the NexION 2000 ICP-MS system, which, says Price, “Advances [made to] the [earlier] NexION 300 series [instruments] … move us onto a higher level when it comes to both performance and flexibility, with technical innovations in the NexION 2000 system that provide the ability to handle any matrix, any interference and any particle size.” The system includes many advances. “One of the important benefits for water analysis is that the NexION 2000 ICP-MS has a completely new solid-state radiofrequency generator design,” Price says, adding that this fire-and-forget generator includes a coil that “does not require cleaning or replacing, is self-cooling and runs at 34 megahertz, which, during extensive testing, was found to be optimal when it comes to stability and ion generation.”
Scientists can test water for various contaminants, including pesticides, with MS, especially when combined with liquid chromatography (LC) or gas chromatography (GC). “A developing trend in GC-MS and LC-MS has been Orbitrap technology for those researchers looking at unknowns and emerging contaminants,” Jack says. “The resolution [provided by] Orbitrap technology allows for more accurate identification of unknowns, including their breakdown products.” This requires technology that is smarter than ever.
The sensors used in water-analysis technology also keep getting smarter. Digital sensors—replacing analog ones—provide the ability to transmit data via various protocols, including Modbus and Ethernet. “Bluetooth capabilities in these sensors have also led to the ability to use smartphone applications for configuration, calibration and even software installation,”
De Dona says. “The development of digital sensor technology has not only allowed the introduction of some sophisticated diagnostics, but also the ability of the sensor to operate independently of a transmitter.” This can be done with Thermo Scientific’s AquaSensor DataStick sensor technology.” These water-analysis sensors can be configured in many ways, including communicating directly with programmable logic controllers or other devices. On the other hand, says De Dona, “The digital sensors can also be connected in a standard configuration to a transmitter like the Thermo Scientific AquaPro, allowing up to four sensor inputs with multiple output and alarm options.”
Laboratory electrochemistry sensors have evolved and continue to push the limits of detection for every water-based parameter, from pH to conductivity to ion-selective electrodes. These sensors, a proven technology for water analysis, have been used as a platform for smart-sensor technology, allowing measurements to be made in the lab, in the field and on-line.
In the lab
Beyond the water that we drink, the quality of the water used in research is critical. “Water analysis in laboratory research translates into super-clean, highly pure water for analytical instrumentation [which is] used in the lab for analytics of samples, preparation of buffers, method development for process control as well as [for] references or [as a] baseline in experiments,” notes Theresa Creasey, head of applied solutions strategic marketing and innovation at MilliporeSigma (Billerica, Mass.). “Calibration of water dispensers for analytical instrumentation is challenging and needs controlled water resources for reliable output and results.”
Scientists can analyze water for experiments with MilliporeSigma’s Spectroquant Prove spectrophotometers, which can run any of the company’s 180 photometric test kits. (Image courtesy of MilliporeSigma.)
To get the system right, MilliporeSigma can help scientists combine the right test kit with its Spectroquant Prove spectrophotometers for water analysis. “The Spectroquant Prove 600 holds a cell shaft for 100-millimeter cells—giving the customer the ability to analyze super-sensitive parameters with simple photometric applications,” Creasey explains. Customers can choose from 180 photometric test kits and the certified reference materials needed to test water samples. She adds, “MilliporeSigma’s Spectroquant Prove instruments measure reliably and precisely across a broad range of concentrations along the complete ultraviolet/visible spectrum.” That helps scientists address water quality for a variety of laboratory applications.
With trillions of gallons of water out there, it might seem like there should be plenty to go around, but every drop counts, and keeping them clean demands careful analysis. Getting the best results ensures safe drinking water and the best science.
Mike May is a freelance writer and editor living in Florida. He can be reached at [email protected].