Q&A

Q: Is the C18 AX isolator column the standard isolator column (P/N 186004476) available from Waters?
A: No, the C18 AX used as an isolator column is a separate part number and the product name is not "isolator column." The suggested part number to use is 186009407.

Q: Are you taking any steps in your laboratory to reduce exposure to your lab personnel preparing/running PFAS analyses? And do you have your chemists take shower before going into this part of the lab? Is it cleanroom quality?
A: We do not have any direct requirements for analysts working on PFAS because we are not a commercial lab. But our analysts do follow best practices for working with PFAS by being aware of the following: no use of cosmetics and personal care products (lotions, sprays, etc.) before entering the lab and while in the lab, no anti-fog sprays, not wearing anything with a water resistant or similar coating/additive, and cleaning products being used in preparation spaces. We use a shared lab space with other scientists working on other applications as well, so we are executing these experiments without using clean rooms or dedicated PFAS space which we believe is similar to how a customer will be working.

Q: We used Wellington PFAS standards. Do you know how your 44 PFAS standards compared to that? Any published papers using your standards?
A: Waters ERA calibrates with Wellington and Absolute Standards. We also analyze 2nd and 3rd sources from AccuStandard and Cambridge Isotopes. To date, we have not published any papers.

Q: Can you expand upon how the system contamination is separated from analytical peaks? I am interested in the physical mechanism.
A: The system contaminants present in the mobile phase (from solvents or LC components) pass through the isolator column before coming into contact with the sample and analytical column. This isolator column has a stationary phase in it (similar to the analytical column). Therefore, the system contaminants are retained for a period of time on the isolator columns before they elute off. This gives a difference in time between when the sample analytes are loaded onto the analytical column and the system contaminants. Therefore, we can get separation/resolution of the contaminants.

Q: Does Waters offer reference standards for PFAS?
A: Waters ERA does not offer calibration standards for any of our PFAS products, but we do offer Proficiency Test (PT) and Certified Reference Material (CRM) PFAS products. A complete listing of our PFAS product portfolio is available on the website.

Q: Sample collection seems to be very challenging. Are there some emerging standard practices for that?
A: Each method typically has standards around how sample collection should be performed. Waters does not work in the sample collection space, so I am not versed on all the up- to- date requirements or suggestions for sample collection.

Q: In your lab(s), how effective have you seen EPA 1633 method perform sample clean up on soils? Does your chromatography look good consistently?
A: We are in the process of running EPA 1633, but have not run all the matrices yet, so I cannot comment on the efficiency of the full required clean up at this time.

Q: The solvent filters for mobile phases for PFAS are different from general LC/MS/MS systems and I have had to track down the filters from a Waters engineer and could not find them on the Waters website otherwise.
A: The PEEK mobile phase tubing sold with the PFAS kit comes with all accessories needed for use, including the filters.

Q: We've found that SPE cartridges come contaminated with PFBA from the manufacturer, generally over 0.400 ug/L. How do your SPE cartridges compare? Are they tested rigorously to ensure there is no contamination with analytes of interest?
A: Oasis WAX for PFAS cartridges are QC tested for a list of 30 PFAS compounds, including PFBA prior to release. The cartridges must be below a determined limit to be sold. For PFBA, the limit is 5 ng/L which is based on detection limits of the instrument and the method being used for the QC analysis.

Q: What can you do about contamination in organic solvents? How can you get rid of it?
A: It is difficult to remove PFAS contaminants from organic solvents. The best suggestion is to evaluate varied brands and grades to find one that has the least amount of contamination. Some things to think about when purchasing solvents is the type of bottle they come in, including the cap and cap seal used. Processing of solvents and reagents prior to bottling can also contribute to PFAS contamination so it is not always clear, unfortunately.

Q: Any suggestions for detection of PFAS on clothing?
A: Clothing is not an area we have actively worked on in- regards to PFAS, so I do not have any specific suggestions. You could potentially try to adapt a method used for solids sample analysis. I would start with that.

Q: Is there a labeled standard available for every PFAS (or for a group of similar PFAS)?
A: To my knowledge there is not a mix of labeled compounds all in one mix that represents all 44 PFAS components.

Q: Can you add an isolator column to the column tracker in MassLynx?
A: No, there is no way to add an isolator column into the column section on the MassLynx console.

Q: What are your suggestions for a more flexible transfer tubing than the PEEK tubing?
A: I do not have a suggestion for a tubing that is better than PEEK for PFAS analysis.

Q: Food?
A: Please see application notes 720007333, 720007482, 720007687.

Q: I am planning to do PFAS analysis in milk samples. Any tip on this topic?
A: Please see application note 720007687.