Detection of per and polyfluoroalkyl substances using total organic fluoride

Patent metadata

Field	Value
Publication number	US-2025067711-A1
Application number	US-202418941328-A
Country	US
Kind code	A1
Filing date	Nov 8, 2024
Priority date	Jan 20, 2022
Publication date	Feb 27, 2025
Grant date	—

Abstract

An embodiment provides a method for deriving an amount of PFAS substances from a total organic fluoride measurement in a sample, including: removing inorganic fluoride from the sample using one or more of an ion exchange cartridge and an exclusion apparatus; preconcentrating, using a solid phase extraction, at least one PFAS substance in the sample; digesting, using a working electrode and a counter electrode, the at least one PFAS substance to an amount of total organic fluoride; and determining, using an analyzer, the amount of total organic fluoride in the sample. Other aspects are described and claimed.

First claim

What is claimed is:

1 . A method for deriving an amount of polyfluoroalkyl substances and perfluoroalkyl substances (PFAS) from a total organic fluoride measurement in a sample, the method comprising:
preconcentrating, using solid phase extraction, an amount of at least one PFAS substance in the sample; digesting, using a boron-doped diamond (BDD) working electrode and a counter electrode, the preconcentrated amount of the PFAS substance to an amount of total organic fluoride; and determining, using an analyzer, the amount of total organic fluoride in the sample.

2 . The method of claim 1 , wherein the counter electrode is a boron-doped diamond (BDD) electrode.

3 . The method of claim 1 , wherein the counter electrode is a glassy carbon electrode.

4 . The method of claim 1 , wherein the counter electrode is a dimensionally stable titanium-based electrode.

5 . The method of claim 1 , wherein at least one of the working electrode and counter electrode is configured as a bipolar electrode.

6 . The method of claim 1 , wherein the digesting is performed without gold or titanium back contacts.

7 . The method of claim 1 , wherein the analyzer is an optical measurement device.

8 . The method of claim 1 , further comprising measuring a total amount of inorganic fluoride in the sample.

9 . The method of claim 1 , wherein the solid phase extraction includes a hydrophobic solid phase extraction stage that does not retain lower carbon chain (<C5) PFAS compounds.

10 . The method of claim 1 , wherein the solid phase extraction includes a weak anion exchange stage.

11 . The method of claim 1 , wherein, in the preconconcentrating, (i) a portion of the sample is subjected to a hydrophobic solid phase extraction stage that does not retain lower carbon chain (<C5) PFAS compounds, and (ii) another portion of the sample is subjected to a weak anion exchange stage.

12 . The method of claim 1 , wherein the preconcentrating includes retaining the at least one PFAS substance on a solid phase extraction material and then washing the solid phase extraction material to elute the at least one PFAS substance from the solid phase extraction material.

13 . The method of claim 1 , wherein the digesting includes (i) performing electrochemical oxidation with the working electrode and counter electrode at a relatively lower current density; and (ii) performing electrochemical oxidation with the working electrode and counter electrode at a relatively higher current density.

14 . The method of claim 13 , wherein the relatively lower current density is less than 20 mA.

15 . The method of claim 13 , wherein the relatively higher current density is more than 20 mA.

16 . The method of claim 1 , wherein the preconcentrating includes contacting the sample with a solid phase extraction material that does not retain inorganic fluoride.

17 . The method of claim 1 , wherein the BDD working electrode indirectly oxidizes PFAS to carbon dioxide and fluoride using hydroxyl radicals.

18 . The method of claim 1 , wherein the counter electrode reduces water to form hydroxide anions and hydrogen gas.

Assignees

• Hach Co

Inventors

• Rajasekharan Vishnu Vardhanan
• Jackson Cary Burton
• Salzer Matthew Ryan
• Kroll Dan Jonathan

Classifications

• G01N1/405

  by adsorption or absorption · CPC title

• Y10T436/193333

  In aqueous solution · CPC title

• Y10T436/25125

  Digestion or removing interfering materials · CPC title

• Y10T436/196666

  Carbon containing compound [e.g., vinylchloride, etc.] · CPC title

• G01N33/1826

  Organic contamination in water · CPC title