Over the past four years of helping laboratories automate EPA Method 537.1, we have come across several common misconceptions about the method. Many of these trigger unnecessary concerns and often lead to higher costs and inefficiencies.
Here are the top 3 culprits:
1. Teflon is not allowed
This is certainly the most debated subject from our experience. When talking about per and polyfluoroalkyl substances, PTFE is always a four-letter word. However, EPA Method 537.1 does not ban Teflon material, it just needs to be demonstrated that background levels do not exceed 1/3 of the MRL. In other words, don't pull your hair out replacing every last bit of Teflon in your lab, run a blank validation first! For details, refer to section 4.2 of the method.
2. Only polypropylene sample bottles may be used
Polypropylene shortage has been a serious problem since the pandemic, leading to increased costs and delays. Even though polypropylene containers were used in the development of EPA Method 537.1, Section 6 states that "Other plastic materials (e.g., polyethylene) which meet the QC requirements of Section 9 may be substituted". Our low-cost and quick-delivering HDPE bottles are used by many labs that have received accreditation for this method.
3. A batch of samples mean they have to be extracted together
An extraction batch in accordance to EPA Method 537.1 has to include 4 QC samples. What happens if you can only extract 8 samples samples at a time? Does it mean that each group of 8 samples needs to be accompanied by 4 QC samples? That's a lot of extra work!
Fortunately, Section 3.6 defines an extraction batch as up to 20 field samples "extracted together by the same person(s) during a work day using the same lot of SPE devices, solvents, surrogate, internal standard and fortifying solutions". This means that as long as conditions are kept the same, up to 20 field samples can be spread out over separate extractions in a work day. They are considered the same batch along with just 4 QC samples.
Whew, what a relief! Maybe this method isn't that daunting after all, especially when our 8-Channel SPE-03 system takes care of the full extraction. Find out more from the links below:
PFAS Extraction video (EPA Methods 537.1 and 533)
PFAS Extraction video (EPA Method 1633)