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April 24, 2019

What’s in my water? Technologies in water quality analysis

By GE Healthcare Life Sciences

Do we know exactly what’s in our water, be it drinking water or wastewater? In an interview, Professor Knappe, from North Carolina State University (NCSU) talks about how he is directing his research group towards improving ways of analyzing water quality.


Is my water safe?

According to Prof. Knappe, for a while, the answer to that question has been: “Yes, if the drinking water meets the regulatory requirements”.

But the real answer might be a little more complicated than that: “With the onset of more advanced analytical equipment and with a better understanding of the chemicals that are on the market”, Prof. Knappe says his Water Quality and Treatment Research Group “are probing deeper into this question.”

A challenge they face is that the public doesn’t understand how water quality is determined. He says that “the public often thinks that is how my lab works; we receive a sample and five min¬utes later, I can tell you everything that’s in the water… We’ve come a long way in terms of analytical methods, but we’re still very far away from that kind of analysis.”

In reality, analyzing water quality can be quite involved. The US Environmental Protection Agency’s Method 2540D for examining water and wastewater, for example, has multiple preparation steps before even filtering the water sample. In Europe, EN 872 describes a similar standard method. These create a potentially complicated workflow for environmental testing laboratories.

We’ve been working to address this challenge at GE Healthcare Life Sciences with time-saving filter papers for water quality analysis.

The Whatman 934-AH Ready-To-Use (RTU) Glass Microfiber Filter is now one of the most widely used filters for Method 2540D-based suspended solids analysis; a common method of assessing water quality. Similarly, Whatman GF/C RTU Glass Microfiber Filters support the European EN 872 workflow for water analysis.

Suspended solids analysis provides a quick and easy measure of the level of pollution within a sample of water by deducting the filter weight from the final filtered sample weight. GE Healthcare pre-labels the weight of every Whatman 934-AH RTU Glass Microfiber Filter produced, effectively eliminating five of the preparation steps (Fig 1).

Comparing filtration steps in compliance with method 2540D of traditional glass fiber filters and Whatman 934-AH RTU

Fig 1. Filtration steps in compliance with method 2540D of traditional glass fiber filters (top) vs. Whatman 934-AH RTU (bottom).

Unknown Compounds

One of the greatest challenges is dealing with unknown compounds in water.

According to Prof. Knappe, “Only about 100 chemicals are regu¬lated in U.S. drinking water and for wastewater discharge. That leaves a very large number of compounds that are not studied, which creates the chal¬lenge of how we deal with the remain¬ing 99,900+ compounds.”

But there is a way around this, though Prof. Knappe suggests a precautionary approach: “If removing a contaminant from water is very difficult, then it probably should not be discharged into a drink¬ing water source to begin with.”

He says that “it is virtually impossible to do such a risk assessment one chemical at a time. If we don’t know the toxicity of a particular chemical, then maybe its presence should not be allowed in water at any measurable level.”

The advent of high-resolution mass spectrometry is now enabling researchers to look for unknown compounds in water. Does this mean we’re finally able to answer the key question: “Is my water safe?”

Using High-Resolution Mass Spectrometry in water analysis

Recent technologies, such as high-resolution mass spectrometry, have the potential to address some of the challenges around water quality analysis. Two key limitations of these technologies are cost and training.

As Prof. Knappe explains, “High-resolution mass spectrometers are expensive and require operation and data interpreta¬tion by highly skilled analytical chemists.” Another challenge is that “we might learn whether a particular compound is present, but we cannot quantify the levels that are in the water if we don’t have an analytical stan¬dard available for that chemical.”

So, perhaps it’s not so easy.

“To elucidate the exact chemical structures of particular molecular features is still not easy. So, we still have a long way to go to answer the questions, ‘Is the water safe?’ and ‘What is in my water?’. [We’re limited by] the number of compounds we can capture in a par¬ticular method, given the wide range of contaminants that are out there.”

But Prof. Knappe’s team are making some interesting progress.

“The increasing sensitivity of analytical instruments allows us to combine methods such that we can analyze 1,4-dioxane, a more poorly responding compound, together with more strongly responding volatile organic compounds (VOCs). In our research group, we are developing such a method at the moment.”

Biochar: enhancing water quality, naturally

Prof. Knappe and his team are also looking at ways to improve water quality. Biochar, Prof. Knappe suggests, could be a natural solution to water treatment: “The idea behind biochar is to make an adsorbent that’s more economi¬cal and can be locally produced, which is especially attractive in developing countries.”

The challenges of testing and maintaining water quality in remote locations and developing countries are well known.

Developing countries are some of the worst affected by water pollution, due to the rapid industrialization coincident with their development. Being able to produce a natural, organic adsorbent locally could be an excellent remedy.

Prof. Knappe believes “there are some interesting opportunities to start thinking about taking organic matter that may be viewed as waste and turning it into a useful mate¬rial, whether that’s wastewater biosolids or organic matter from certain waste streams such as those produced in agriculture or by the forest products industry.”

Previously, his team has studied the use of granular activated carbon (GAC) for water treatment: “GAC treatment is quite effec¬tive at removing precursors for disinfec¬tion byproducts. It’s also an excellent tool to lower concentrations of a wide range of trace pollutants that are in water, both regulated and unregulated.”

Further work is required to find a natural alternative to GAC. “Right now, we can come close under certain conditions, and there is ongoing research to improve the material even further, but it’s currently not as effective as GAC.”

GE Healthcare’s filters and filtration devices can be used to help compare the effect of different adsorbents, like GAC and biochar, on water quality. For example, the Mini-UniPrep syringeless filters enable quick and easy sample filtration in the field (often literally!).

Ready-To-Use filters like Whatman Grade 934-AH and Whatman GF/C RTU minimize additional equipment requirements for sample prep.

Harmonizing Analytical Methods

Prof. Knappe believes that “harmo¬nizing analytical methods is important”. There’s still a way to go before we fully understand all the compounds in our water, but dedicated people like Prof. Knappe and his team are addressing that challenge.

As for GE Healthcare, with 250 years of experience in filtration and an established supply chain, Whatman ready-to-use filters and filtration devices can be incorporated into global environmental monitoring protocols with confidence, knowing that the same product and level of quality will be available in years to come.

The manufacturer-controlled preparation and product quality eliminates any batch-to-batch, lab-to-lab, or person-to-person variation, whilst maximizing workflow efficiency. Whatman RTU filters can also be tailored to different stages of readiness, to fit the workflows of different water quality testing labs.

At GE Healthcare, we provide high-quality filtration products to support all aspects of environmental monitoring and research. Find out more about testing drinking water and wastewater with the aid of filtration. Or, use our Filter Selector tool to find the most appropriate filter for your environmental monitoring needs. For help with any other aspect of your workflow, including any custom filtration needs, contact the GE Healthcare Scientific Support team or your local representative.