The amount of carbon in an organic compound makes up the so-called total organic carbon (TOC), which serves as a crucial metric in a wide range of processes. For instance, TOC can indicate the quality of water or the cleanliness of a pharmaceutical process. TOC also comes into play in environmental control and waste management. This measurement becomes increasingly common as TOC analyzers become more widely available.
“The TOC-analyzer market is growing,” says Stephen J. Poirier, growth and strategy leader at GE Power & Water (Boulder, CO). He points out that environmental labs use this technology in a range of applications and that pharmaceutical companies must often report TOC in processes for regulatory compliance. He adds, “Some scientists look at TOC in research applications, and there are even applications at universities where scientists measure TOC.”
A tale of two analyzers
In general, TOC analyzers employ one of two approaches. The combustion technique is widely used in environmental TOC analysis, such as for wastewater. Here, the device subjects a sample to a high temperature, 600 to 1,000 degrees Celsius, which combusts the carbon to carbon dioxide and the nitrogen compounds to nitrogen monoxide. Then, nondispersive infrared analysis measures the carbon dioxide to determine the sample’s TOC.
The second approach uses ultraviolet light to oxidize the carbon to carbon dioxide. “Here the advantage is that the process does not drop out precipitates like the high-combustion approach can,” says Poirier. After the oxidation, this technique measures the carbon dioxide with nondispersive infrared analysis or membrane conductivity.
With either approach, similar trends drive TOC analyzers. “For one thing,” says Poirier, “the analysis time needs to be shorter. You need a quicker time to results to increase the throughput.” To further increase productivity, the TOC analyzer must also be robust to increase its uptime. Poirier adds, “The scientists want to detect smaller quantities of organic carbon compounds.”
In solid TOC analyzers, automation constitutes another trend, according to Bernd Bletzinger, product specialist for total organic carbon analyzers at Analytik Jena (Jena, Germany). “That makes it easy to use the instrument with higher productivity and flexibility.” He adds that contract labs handle so many samples in a day that they require automation. “This leads to more reproducible results and significantly reduces required manpower,” he says.
Advancing the analysis
Beyond the approach the instrument uses to measure TOC, customers need simplified tools for collecting and reporting the results. As Poirier explains, “A high-throughput lab needs very easyto- use but comprehensive data-analysis tools.” The particular tools will depend on the application. Moreover, a customer might need flexibility to adjust the analysis for a specific application.
At contract packaging company Aphena Pharma Solutions (Easton, MD), for example, chemists use TOC analyzers to test cleaning-validation samples from the assembly lines. “Our assembly lines need to be cleaned with a protocol prescribed by a customer, and samples from that process come up for analysis,” says Diane Elliott, an analytical chemist at Aphena. So a TOC analyzer determines whether the cleaning reached the required standard. This company also uses TOC analysis to test its United States Pharmacopeia (USP) purified water system.
In analyzing the cleaning samples, Elliott would like a little more control over starting and stopping the TOC analyzer. For example, once it starts analyzing a sample, the machine essentially has a one-track mind. Elliott and her colleagues can’t even print out previous results while the TOC analyzer is working. She adds that she’d like to be able to add samples without pausing the entire run and waiting for the current sample to finish, which can take as long as 40 minutes, before another can be added.
Elliott would also like to add specifications to a protocol, such that the instrument would simply print out a pass or fail on that test. “That could cut down on analyst errors, like misreading a number,” she says.
Some vendors understand that customers need to adjust the software for specific challenges. To give the analytical software more flexibility, Poirier and his colleagues start with their core software platform and modify it with various applications as needed. “We have an app for pharma users, apps for drinking water that a municipality might want, and so on,” Poirier says.
To make TOC analyzers more accurate, the devices can be incorporated into a complete process. As an example, Poirier describes an industrial application: “In the water line for a semiconductor plant, for example, the TOC analyzers can be integrated with the sample stream for continuous measurements.” In this scenario, the TOC analyzer constantly samples the water as it flows through the pipe. “This provides more data, and the sample doesn’t get exposed to environmental contamination,” Poirier adds.
The combination of automation in TOC analyzers and putting them in line with other processes should expand the use of this technology and increase its accuracy. Bletzinger notes that accuracy also improves from the use of self-check systems in a TOC analyzer. “Our instruments can automatically check the basic functionalities, like gas flow, temperatures, and leaks,” he says. “This helps to provide reliable results and data, and it makes it easier to operate the system.” Bletzinger adds, “There are very few parts that have to be exchanged, and the detector is very robust and needs no maintenance.”
Such robust systems in TOC analyzers reduce the attention the instruments need and decrease the need for operator expertise. Combining this with the ability to adjust a system’s software for a specific purpose makes TOC analyzers more adaptable than ever, which should lead to more integration of this technology in the future. Likewise, making this technology simpler enhances the odds of technicians using this tool in basic research.