Nitrosamines: Development of Method EEA 521.1
Nitrosamines, an unregulated contaminant of concern, have been getting a lot of attention in Monrovia, California the last few years. Eurofins Eaton Analytical has been diligently working on new method development since the onset of EPA’s Second Unregulated Contaminant Monitoring Rule (UCMR 2), published back in 2007. UCMR 2 required contaminant monitoring between 2008 and 2010 for 25 specific compounds using analytical methods developed or approved by EPA. Nitrosamines were monitored as part of this UCMR program, yet as of today, they have yet to be regulated by EPA.
What are nitrosamines?
The nitrosamines group consists of a large number of compounds formed by various combinations of amines and nitrogen compounds, each having a foundational structure of N-N=O. Hundreds of nitrosamine compounds have been labeled carcinogenic in recent years. The most well-known, N‑nitrosodimethylamine (NDMA), is included in a list of compounds with direct concern to the water treatment community. NDMA in its pure form is found in the environment as a low-odor, yellow and oily semivolatile, and is more often found as a by-product of a chemical mixture. Nitrosamines have been used in the manufacture of cosmetics, pesticides, rubber products and fuel. Today, NDMA is only produced for research purposes.
NDMA as a disinfection byproduct can be present at low concentrations in treated drinking water. The compound is also present in source water under the influence of wastewater discharge. The scenario in which a downstream municipality draws drinking water from recycled sources is becoming more common as communities expand their reach for additional drinking water supplies. Due to the potential presence of NDMA in water reuse, many water providers are required to monitor for these compounds.
There have been various responses in North America to the presence of NDMA. Canada has set a drinking water standard for NDMA, being the only government entity that has promulgated a formal drinking water standard for a Nitrosamine. Similarly, the California Department of Health Services has set notification levels for Nitrosamine compounds NDMA, NDEA, and NDPA. California became the first state to set a public health goal for NDMA at 3 parts per trillion (ppt). This action is a precursor to formal regulation. Laboratories like Eurofins are currently using Chemical Ionization GC/MS techniques and can detect and report NDMA at very low levels (ppt). The continued demand for Nitrosamine analysis has motivated Eurofins teams to improve the current analytical methods, including the one used for the UCMR 2 program, EPA Method 521.
Analyzing for nitrosamines by EPA Method 521
EPA Method 521 was developed for EPA's UCMR 2 for the detection of nitrosamines. If NDMA or other nitrosamines become regulated drinking water contaminants in the future, the method would also be used for compliance monitoring. The original version of the method was written around a technology (ion trap with chemical ionization) that is no longer manufactured by the vendor and is a time-consuming analytical procedure. Since the EPA may in the future regulate nitrosamines in drinking water and it is already in demand in states like California, Eurofins, led by Dr. Andrew Eaton, started the research at looking at analytical methods that EPA might consider deeming an acceptable alternative.
Method Development - EPA Method 521 from GC/Ion Trap MS to GC/Triple Quadrupole MS
Eurofins looked at the development of a modified method for analyzing nitrosamines because the EPA remains interested in this contaminant, and states that already have set standards and requirements. Even though the regulation of nitrosamines is not promulgated, there is a fear that when it is passed, the ion trap method may no longer be available and EPA cannot regulate a compound without a viable analytical method. Eurofins also realized that EPA was willing to provide a technical review of an alternative method that did not change the sample preparation steps. So Eurofins worked with EPA to determine the amount and type of data that they would deem appropriate to approve a new improved version.
In 2017, Dr. Eaton and his technical team designed and developed a project that was to directly compare Triple Quadrupole GC/MS (QQQ GC- MS/MS) and the currently used Ion Trap GC/MS (IT GC-MS) method using split sample sets. This was conducted in three phases. Eurofins followed Method 521 sample prep methods and then analyzed samples using QQQ GC-MS/MS in EI mode rather than IT GC-MS ion trap in CI mode. The extraction remains the same with the difference being in the analytical step which includes chromatography, ionization, and detection. The method was validated in three different labs. The new method that was validated was written up based on this these studies and submitted to EPA for review. On March 13, 2018, the EPA issued a letter of equivalency to the original 521 method, blessing EEA Method 521.1 for the Analysis of Nitrosamines in Drinking Water by GC/MS/MS as a method that provided technically equivalent performance to Method 521.
The Eurofins Eaton Analytical result
Ultimately, since the EPA has determined that Method EEA 521.1 is an acceptable alternative for EPA Method 521 in analyzing nitrosamines, Eurofins Eaton Analytical continues to lead as the nation’s experts at nitrosamine analysis using both Ion Trap (IT) and now Triple Quadrupole (QQQ). EEA Method 521.1 has lowered detection limits, thus quantitation at lower concentrations has also lowered the chances for false positives/negatives. Analysis times have improved from the IT time of 40 minutes and now can be completed in 15 minutes with the QQQ. With the new method, the detector scans faster, allowing chromatograms to be shorter with better peak shapes. This significantly improves precision and throughput on the instrument. Lastly, the QQQ is more reliable than IT since it has less downtime with less chance of catastrophic failure, an improvement since vendor support is no longer available for the IT.
Water Systems and Regulators can now be confident in the EEA Method 521.1 results for Nitrosamine analysis, since the formal regulation may be just down the promulgation road in the years to come. Laboratories will be able to increase instrument capacity by almost doubling throughput, reducing internal analytical costs, improving sensitivity and cutting runtime down to less than half of the previous method. To the water c, it means quicker turnaround time, lower detection levels and ultimately a larger Nitrosamine compound list. For Eurofins and Dr. Eaton’s Team, it has been an environmental technology improvement and hope for the future of method regulation.
To learn more about the method development, review Agilent’s presentation on “Updated Method for the Analysis of Nitrosamines in Drinking Water Using GC-MS/MS (EEA 521.1)”. The recorded webinar, led by Dr. Andy Eaton, Technical Director/Vice President of Eurofins Eaton Analytical and Craig Martin, Marketing Manager of Agilent Technologies, Inc., is available online to watch.