UNDER

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ENVIROCLASS

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Introducing HALO® PFAS Column Solutions INTRODUCTIONPer- and polyfluoroalkyl substances (PFAS) are human-made fluorinated compounds that contain carbon-fluorine bonds. With desirable properties such as resistance to heat, stains, and water, they were and some continue to be, used for consumer products such as food packaging, nonstick cookware, food processing equipment, cleaning products, fire-fighting foams, paints, and stain- and water-resistant fabrics and carpeting. These compounds do not break down easily due to the presence of the strong carbon-fluorine bonds, which has earned them the nickname “forever chemicals.” There are nearly 5000 PFAS compounds mainly because as some were banned others were created to replace them. Part of the problem with PFAS is that they are found everywhere and have entered water supplies. Another issue with PFAS is that only certain compounds have been extensively studied for their impact on human health. There is worldwide concern about the presence of PFAS in the environment. In the US, the Environmental Protection Agency (EPA) has developed methods for the analysis of drinking water (533 and 537.1) and another method for the analysis of groundwater, surface water, and wastewater samples (8327). The EPA has a health advisory limit of 70 ppt for levels of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) either combined or individually, but it is non-enforceable and non-regulatory. This leaves individual states to determine maximum levels for themselves. In Europe, the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation restricts PFOA and its precursors while PFOS is restricted by the EU persistent organic pollutants (POPs) Regulation. More comprehensive regulations are currently under development in the EU.

People are exposed to PFAS in several ways. One way is through eating PFAS contaminated food. The food can become contaminated through the soil and water used to grow it, the packaging that contains the food, or through PFAS contaminated equipment that processed the food. Another way people are exposed is through PFAS-containing products, such as nonstick cookware, carpets, clothes, and food packaging. Where water has become contaminated with PFAS, the drinking water can expose people to PFAS. These sites are normally near PFAS production plants or facilities that manufactured PFAS-containing products. Other typical locations are near oil refineries, airports, or military bases where aqueous film forming foam (AFFF) formulations were used to extinguish fires mainly during training exercises.

Since PFAS accumulate in the body, the increased level of these compounds over time may cause health effects. Exposure to PFOA and PFOS can cause increased cholesterol, low birth weights, immune system effects, cancer (PFOA), and thyroid hormone disruption (PFOS). While the health effects of PFOA and PFOS have been studied, the same is not true for all of the 1000’s of PFAS compounds. Consequently, research continues to uncover the impact that PFAS have on human health. It was recently reported that 6:2 fluorotelomer alcohol (6:2 FTOH) is more toxic than perfluorohexanoic acid (PFHxA), which had been used to assess the toxicity of 6:2 FTOH. This has prompted the manufacturers of food packaging that contain 6:2 FTOH to voluntarily phase out the sale of these products in the US over a three-year time span beginning in January 2021.

AMT-08-020

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HALO® PFAS and HALO® PFAS Delay columns have been developed specifically for the analysis of PFAS. The densely bonded, extensively endcapped ODS stationary phase of HALO® PFAS provides an application assured and method qualified solution for PFAS analysis. The highly retentive endcapped alkyl silane of the HALO® PFAS Delay column provides high retention of PFAS compounds across various mobile phase conditions and is used to delay background instrument PFAS contamination from coeluting with analyzed samples. Figure 1 shows the HALO® PFAS and HALO® PFAS Delay particle and ligand structures.

APPLICATIONSEvery HALO® PFAS lot is quality assurance tested by LC-MS/MS analysis of a mix of 17 PFAS consisting of a broad range of short and long chain compounds. Set specifications ensure reproducible results across multiple lots. An example LC-MS/MS MRM QA separation is shown in Figure 2.

Figure 2. Representative MRM QA chromatogram showing the analysis of 17 PFAS compounds using HALO® PFAS.

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Delay Column: HALO® PFAS Delay, 2.7 µm, 3.0 x 50 mmAnalytical Column: HALO® PFAS, 2.7 µm, 2.1 x 100 mmMobile Phase: 10 mM Ammonium Acetate [A]; Methanol [B]Gradient: 33-98% B in 18 minFlow Rate: 0.4 mL/minInitial Back Pressure: 420 bar

Temperature: 35 °CDetection: Negative ESI, MRMInjection Volume: 1 µLSample: PFAC-MXB (Wellington Laboratories)Concentration: 100 ppb in 96% Methanol

1. PFBA2. PFPeA3. PFBS4. PFHxA5. PFHpA6. PFHxS7. PFOA8. PFNA9. PFOS10. PFDA11. PFDS12. PFUnDA13. PFDoDA14. PFTrDA15. PFTeDA16. PFHxDA17. PFOcDA

TEST CONDITIONS

PEAK IDENTITIES

Figure 1.

Time (min)

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Figure 3. PFOA found in a null injection run on a HALO® PFAS Delay column and a HALO® PFAS column. (Conditions same as Figure 2.)

For those just beginning to venture into PFAS analysis, the concept of a delay column may be unfamiliar. PFAS contamination is commonly found in the HPLC equipment used to conduct the experiments. This contamination stems from the solvent bottle caps, PTFE tubing, filters, sample preparation consumables, solvents, and even the laboratory environment itself. While fluorocarbon-free replacements exist, there may still be system contamination which is detrimental for trace analysis. The HALO® PFAS Delay column is meant to trap and delay any PFAS that is unrelated to the sample of interest. Figure 3 shows a null injection (gradient was run, but no sample was injected) and PFOA from the system is clearly visible. The prevalence of PFOA is commonly observed as an instrument materials contaminant.

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When a sample is run, the PFOA from the LC instrument elutes at a later time compared to the PFOA from the sample. See Figure 4.

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Figure 4. PFOA from sample and LC system run on a HALO®

PFAS Delay column and a HALO® PFAS column.

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Figure 5. HALO® PFAS separation of branched and linear PFHxS isomers from a well water sample.

One of the challenging aspects to PFAS analysis is the presence of linear and branched isomers. Branched isomers are a byproduct of the process of electrochemical fluorination (ECF) used to manufacture PFAS. Conversely, when telomerization is used, only linear isomers are formed. Branched PFAS isomers, which are more polar, are less retained compared to the linear PFAS isomers. This explains why branched isomers are found in water while linear isomers are found in soil and sediment. In Figure 5, a well water sample is run on a HALO® PFAS column and shows the excellent resolution of the branched and linear isomers of PFHxS.

Analytical Column: HALO® PFAS, 2.7 µm, 2.1 x 100 mmDelay Column: HALO® PFAS Delay, 3.0 x 50 mmMobile Phase A: 20 mM Ammonium Acetete B: MethanolGradient: Time %B 0.0 20 15 90 20 90

Flow Rate: 0.4 mL/minPressure: 505 barTemperature: 44 °C

Detection: -ESI MRMInjection Volume: 2.0 µLSample Solvent: Methanol (96%) Water (4%)LC System: Agilent Triple Quadrupole LC/MS 6400

TEST CONDITIONS

PEAK IDENTITIES

1 PFBA

2 PFMPA

3 PFPeA

4 PFBS

5 PFMBA

6 PFEESA

7 NFDHA

8 4:2FTS

9 PFHxA

10 PFPeS

11 HFPO-DA

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13 PFHxS

14 ADONA

15 6:2FTS

16 PFOA

17 PFHpS

18 PFNA

19 PFOS

20 9CI-PF3ONS

21 8:2FTS

22 PFDA

23 NMeFOSAA

24 NEtFOSAA

25 PFUnA

26 11CI-PF3OUdS

27 PFDoA

28 PFTrA

29 PFTA

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Figure 6. Rapid separation of 33 PFAS in under 5 minutes on a HALO® PFAS column.

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With all of the research being done on PFAS, a high throughput method is essential for both time and solvent savings. HALO® PFAS which utilizes Fused-Core® technology is well suited for rapid PFAS analysis. Figure 6 shows an efficient analysis of 33 PFAS in less than 5 minutes. These compounds comprise all of the target analytes in EPA methods 533, 537.1, and 8327.

Analytical Column: HALO® PFAS, 2.7 µm, 2.1 x 100 mmDelay Column: HALO® PFAS Delay, 3.0 x 50 mmMobile Phase A: 10 mM Ammonium Acetete B: MethanolGradient: Time %B 0.0 33 4.0 98 4.10 100 6.00 100 6.10 33 7.50 EndFlow Rate: 0.4 mL/minPressure: 479 barTemperature: 35 °CInjection Volume: 2.0 µLSample Solvent: Methanol (96%) Water (4%)

TEST CONDITIONS

Time (min)

PEAK IDENTITIES

1 PFBA

2 4:2FTS

3 PFPeA

4 PFBS

5 PFHpS

6 PFPeS

7 PFMPA

8 PFHxA

9 PFEESA

10 HFPO-DA

11 PFHxS

12 NaDONA

13 ADONA

14 FOSA

15 PFOA

16 PFMBA

17 PFHpA

18 PFOS

19 9Cl-PF3ONS

20 8:2FTS

21 PFNS

22 PFDA

23 N-MeFOSAA

24 PFNA

25 NFDHA

26 PFUnA

27 N-EtFOSAA

28 6:2FTS

29 11Cl-PF3OUdS

30 PFTrDA

31 PFDoA

32 PFTeDA

33 PFDS

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CONCLUSION

The combination of HALO® PFAS Delay and HALO® PFAS columns offers a complete solution for PFAS analysis. HALO® PFAS lots are quality assurance tested specifically with a mixture of 17 PFAS compounds. The HALO® PFAS Delay efficiently traps and delays PFAS from the LC system. Whether the goal is high resolution or high speed, HALO® PFAS columns deliver rugged, reproducible performance for the most challenging environmental sample matrices.

ORDERING INFORMATION:

ANALYTICAL COLUMNS

Dimensions: ID x Length (in mm) PN

2.1 x 50 92812-413

2.1 x 100 92812-613

2.1 x 150 92812-713

2.1 x 250 92812-913

3.0 x 50 92813-413

3.0 x 100 92813-613

3.0 x 150 92813-713

3.0 x 250 92813-913

DELAY COLUMNS

Dimensions: ID x Length (in mm) PN

3.0 x 50 92113-415

4.6 x 50 92114-415

SPECIFICATIONS

Column Particle Size (µm)

Surface Area (m2/g)

Low pH/T Limit

High pH/T Limit Endcapped

PFAS

Analytical2.7 135 9/40 °C 2/60 °C Yes

PFAS

Delay2.7 90 9/40 °C 2/60 °C Yes