Volatile compounds, complex sector - meeting the many challenges of testing for VOCs
Protecting the world from Volatile Organic Compounds (VOCs) is a pressing and multi-faceted issue. It’s also one that presents analytical scientists with a particularly complex and demanding set of challenges.
Volatile, persistent, and dangerous
VOCs are commonly referred to as being ‘everywhere’ in our post-industrial ecosystem because they are released by an immense range of human activities – from manufacturing, construction and transportation to cooking, cleaning and even personal care. Although by definition volatile, VOCs from household and industrial products are also persistent in our environment – resulting in “vast reservoirs” of pollutants in our soils and wastewater.
The hazards of photochemical smog that VOCs help create – including carcinogens, heart and lung problems and damage to plant and animal life – are already well known. But concern is also mounting about the role of VOCs such as cleaning products, perfumes and paints in indoor air pollution, which the US Environmental Protection Agency (EPA) estimates is commonly two to five times higher than outdoor pollution levels. According to a study published by Berkeley Lab in September, overhead vents or diffusers that supply heated air can also lead to hazardous “thermally stratified” conditions within rooms - meaning that airborne contaminants may not be effectively dispersed, and potentially exposing occupants to much higher levels of pollution. In an era when humans spend 90 per cent of their time indoors – a trend exacerbated by the pandemic – the ability of household goods to emit large amounts of particle-producing VOCs has therefore come under increased scrutiny.
Growing, but complex regulation
The scale of the dangers that VOCs present to both humans and their environment has prompted regulators across the world to issue an “ever-growing number of emission controls, product specifications, monitoring and remediation plans.” The EPA, the European Union (EU), and the Standardisation Administration of China (SAC) are amongst the statutory bodies that have set out guidelines and criteria for residue monitoring and established ranges of substances to be tested. For example, the EPA has mandated VOC limits for a wide range of consumer products in its National Volatile Organic Compound Emission Standards for Consumer Products document, but California and several other states have also drafted their own limits for consumer VOCs, which can sometimes be tougher than those set at federal level. Canada and China updated their national regulations for VOCs in personal and domestic products and industry in 2019 and 2020 respectively, whilst California recently announced proposals to lower VOC limits in household goods still further between 2023 and 2031.
Global variations in the classification of VOCs and differing regulatory demands are among the factors that make analytical testing for VOCs a complex task for scientists, however. For example, the EPA notes in its Technical Overview of Volatile Organic Compounds that it uses volatility in its definition of a VOC, whereas the EU and the World Health Organisation (WHO) classify VOCs by boiling point. The EPA also considers outdoor and indoor VOCs to be two different classes, requiring different regulation and testing, and admits that its own terminology regarding VOCs has caused some “misunderstanding and confusion”. For example, it says that the decision to change the term for organic compounds in outdoor air from Reactive Organic Gases to VOCs may have led manufacturers and third-party certification organisations to think of VOCs as “only those regulated by EPA for outdoor air.” This could potentially lead to people mistakenly being exposed while indoors to dangerous VOCs excluded from consideration for outdoor air. These include methylene chloride, a potential human carcinogen used in paint stripper, or perchloroethylene, a probable carcinogen used in dry cleaning.
The leading analytical scientist John Points has also noted that testing guidelines for VOCs are complicated further by authorities requiring them to be measured in subtly different ways –resulting in different measurement methods, even in specific areas. For example, in Germany, VOCs must be measured as toluene equivalents by the sum of peaks between n-hexane and n-hexadecane on a five per cent phenyl gas chromatography column, while certain specified VOCs must be quantified against their own reference standards rather than versus toluene. In the UK, by contrast, VOCs evolved from indoor paints must only be measured as toluene equivalents (TVOC).
How to test reliably for VOCs
Reliable analytical testing is an indispensable tool that underpins the many and tightening regulations around the globe, as well as efforts to monitor VOC pollution levels and clean up the environment. Varied definitions, differing regulations and the huge chemical diversity of VOCs means that they present a uniquely complex analytical challenge and require laboratories to assess their aims and methods carefully at all times. As Points states, our plans to repair the damage caused by VOCs “will only be effective if supported by laboratories who appreciate exactly what they are trying to measure, why they are measuring it, and the best method to achieve this.”
Because VOCs are so chemically diverse, no single test method will cover them all, and so all methods will involve some element of compromise. Before they can begin their work, laboratories need to discuss and agree with their customers both the purpose of their analysis and the VOC definition that will be used. Such an approach conforms to the 2017 revision of ISO/IEC 17025, which mandates the communication and agreement of requirements before a laboratory starts its analytical work. These discussions may help decide on a test method, but should at least establish the analytes to be measured, the reference standards used and the expression of results.
In terms of calibration and quality control, running negative and positive controls to verify the performance of the method on each day is crucial to a successful outcome. A high-quality, traceable reference material of each VOC measured is also essential when using quantitative methods, and in addition can ensure that your laboratory complies with a wide range of regulations and methods throughout the world (including EPA 8260, 8020, 8021, 502, 503 and 24.2; Directive 2004/42/EC; ap-d181 in Australia and the South Korean Clean Air Conservation Act).
Laboratory and quality control managers will therefore need to partner with trusted reference materials providers who can also keep them up to date with the latest regulations and industry news. Dr. Ehrenstorfer’s range of VOC reference materials help you to do just that.
We have over 400 products to test for VOCs, and are proud to announce the launch of 21 new reference materials, many of them focused on specific EPA methods, such as 502, 8015 and 8020.
The majority of our reference materials and certified reference materials are produced under the scope of our ISO 17034 accreditation and verified in accordance with ISO IEC 17025 to guarantee the highest quality.