Today, chlorine disinfects nearly all processed drinking water. The chlorine, though, can react with natural organic material in water to produce trihalomethane (THM) compounds, which can be carcinogenic.
The more organic material in the water, “the higher the THMs are likely to be,” says William Rauch, president of KAR Laboratories (Kalamazoo, MI). The carbon levels in the water provide an indication of the level of organic material, so water-treatment facilities often measure the total organic carbon (TOC) or dissolved organic carbon at various steps throughout the process to monitor the removal of the natural organic material. Consequently, water comes out free of contamination and carcinogens.
The water that we drink comes from many sources, including lakes and streams, runoff water, and wells. At the University of California, Riverside, David H. Lyons, laboratory safety officer in the department of environmental sciences, and his colleagues use a Shimadzu TOC-V analyzer. Some of the biggest improvements in measuring TOC arise from better detectors. As Rauch explains, “In recent years, membrane conductivity has been achieving low levels of detection, and nondispersive infrared is sensitive as well.”
Some applications, such as municipal water treatment, allow for fixed testing equipment, but portable equipment can come in handy too. Even in the pharmaceutical industry, scientists can benefit from TOC equipment that can be taken to where it’s needed to ensure water quality from research through manufacturing.
The new 450TOC portable analyzer from Mettler Toledo Process Analytics (Billerica, MA), says product manager Peggy Banarhall, complies with the United States Pharmacopeia’s guidelines for measuring TOC for ultra-pure water samples as well as for Water for Injection—literally, water that is pure enough to inject into someone—and purified water. The 450TOC is compliant with USP test chapter TOTAL ORGANIC CARBON. She adds that this TOC platform also complies “with similar guidelines for other global pharmacopeia.”
This small analyzer measures conductivity, temperature, and TOC. When testing water with this device, no chemical reagents are needed, and it has no moving parts, which makes it easy to calibrate and maintain. Its portability, says Banarhall, means that it “can be installed anywhere for rapid troubleshooting of a pure water sample.”
Sometimes, people without any equipment at all want to test drinking water, say, from a well. The Kit360 from KAR can do just that. Use the kit’s containers to collect samples and send them to the lab. In 10 business days, the user receives an analysis, which includes 323 tests, including TOC.
The water that we drink or use in industry makes up just part of the market for carbon analysis. According to “Global Packaged Wastewater Treatment Market 2016-2020”—a market study from Technavio—the market for packaged wastewater treatment in North and South America will increase at a compound annual growth rate of more than 9 percent through 2020. TOC analysis will grow with this.
One thing that a wastewater plant measures is the biological oxygen demand (BOD), which shows how oxygen must be dissolved in the water for biological organisms to process organic material. In brief, a measurement of BOD indicates how thoroughly water has been cleaned.
According to the U.S. Code of Federal Regulations (CFR)—specifically, 40 CFR Part 133.104(b)—a TOC measurement can be used in place of a BOD measurement in some situations. “TOC and BOD often correlate well in municipal effluents, but may not with some industrial discharges,” says William Lipps, environmental/ mining marketing manager at Shimadzu Scientific Instruments (Columbia, MD).
A wastewater analysis system can be equipped to measure TOC in different matrices. As Lipps explains, “We have developed applications for the determination of algal mass and measurement of TOC in water samples containing very high concentrations of particulate matter.” The algae can even clog lines in TOC platforms. So Shimadzu’s analyzers include an accessory that homogenizes samples and reduces the odds of clogging.
Other matrices in water can confound carbon measurement. The high concentration of salts in seawater, for example, can make TOC measurements more complicated. So Shimadzu developed a high-salts catalyst that can be used to measure TOC in samples high in total dissolved solids.
TUNING THE TECH
To get more out of water analysis, scientists will keep asking for more from the technology. For example, Lyons says, “Our system cannot be used with highly acidic samples or extracts, and having this capacity to analyze such samples would be very useful.”
Using a Shimadzu TOC-L, Lillian Custals, consensus reference material program manager at the University of Miami, and her colleagues use the non-purgeable organic carbon method. They’ve used this approach to analyze water collected on various scientific cruises. When asked about any improvements that she’d like to see in her instruments, Custals said, “These instruments are very reliable, and up to now I’m very happy with them and the service the company provides.”
The tools for measuring carbon in water will keep getting better. “Technology is always looking for—and finding—ways to get lower detection limits using smaller amounts of sample,” says Rauch. When the levels of carbon in water—even at very low levels—impact the environment and the safety of what we consume, a lower detection limit makes all the difference. An escalating scarcity of clean water makes such measurement capabilities matter more than ever.
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