Sampling for monitoring Per- and Polyfluoroalkyl Substances (PFAS) in surface water, groundwater and pore water

Abstract

Methods of passively sampling PFAS in the environment, PFAS sorbents, apparatus and systems (apparatus plus conditions) for sampling groundwater, porewater, and surface water are described.

1 . A PFAS sorbent having hydrophilic and hydrophobic regions such that it exhibits a log K d  of at least 2.5 for each of PFOA and PFOS and PFHxS; and a reversibility for PFHxA such that when exposed to a large volume of water (e.g., at least one liter of deionized water per 20 μg PFHxA for 3 weeks at 20° C. and ambient pressure) exhibits at least a 20% reduction of adsorbed PFHxA. 
     
     
         2 . The PFAS sorbent of  claim 1  having a log K d  of at least 3 for each of PFOS and PFHxS. 
     
     
         3 . The PFAS sorbent of  claim 1  wherein the material has a log K d  of 10 or less, or 7 or less, or 5 or less for each of PFOA and PFOS and PFBS. 
     
     
         4 . The PFAS sorbent of  claim 1  wherein the sorbent is a single material. 
     
     
         5 . A method of measuring PFAS, comprising: placing the sorbent of  claim 1  in water for at least 24 hours, in some embodiments at least 5 days, in some embodiments at least 3 weeks, in some embodiments one to four weeks;
 removing the sorbent from the water; 
 optionally removing excess water from the sorbent; 
 extracting PFAS from the sorbent using a solvent that does not dissolve the sorbent; and 
 analyzing the extracted PFAS for the amount of at least one component of PFAS. 
 
     
     
         6 . A PFAS groundwater sampler, comprising:
 a housing comprising a wall or walls that define an internal cross-sectional area;   a PFAS sorbent material disposed within the housing;   wherein the sampler has a mass of at least 0.05 grams and a ratio of sorbent mass to housing internal cross-sectional area of no more than 3 g/10 cm 2 .   
     
     
         7 . The sampler of  claim 6  wherein the sorbent is a polymer, optionally a polymeric foam. 
     
     
         8 . A method of measuring PFAS in groundwater comprising:
 placing the sampler of  claim 6  down a well and into groundwater, allowing the sorbent to remain in the groundwater for at least 24 hours, removing the sorbent from the groundwater;
 optionally removing excess water from the sorbent; 
 extracting PFAS from the sorbent using a solvent that does not dissolve the sorbent; and 
 analyzing the extracted PFAS for the amount of at least one component of PFAS. 
   
     
     
         9 - 21 . (canceled) 
     
     
         22 . A method of measuring PFAS in water, comprising:
 placing an open-celled polyurethane foam into the water; wherein the polyurethane comprises ether and/or ester moieties;   removing at least a portion of the polyurethane foam from the water; and   analyzing for PFAS that has been collected in the foam.   
     
     
         23 . The method of  claim 22  wherein the water is porewater. 
     
     
         24 . The method of  claim 22  wherein the water is surface water. 
     
     
         25 . The method of  claim 22  wherein the water is groundwater. 
     
     
         26 . The method of  claim 22  wherein the foam comprises two types of polyurethane. 
     
     
         27 . The method of  claim 26  wherein the two types are ether-polyurethane and ester-polyurethane. 
     
     
         28 . The method of  claim 22  wherein the foam is an ether based polyurethane foam. 
     
     
         29 . The method of  claim 22  further comprising measuring pH, DOC, temperature, and/or ionic strength of the water. 
     
     
         30 . The method of  claim 29  further comprising using the measured pH, DOC and/or ionic strength to adjust at least one K d  value and using the adjusted K d  value to calculate the concentration of at least one PFAS compound. 
     
     
         31 . The method of  claim 22  wherein the open-celled polymeric foam is further characterizable by at least one of the parameters shown in Table 2, 4, or 5 and having a value of ±50% of that parameter as shown in Table 2, 4, or 5. 
     
     
         32 . The method of  claim 31  wherein the open-celled polymeric foam is further characterizable by at least five of the parameters having a value of ±50% of that shown in Table 2, 4, or 5. 
     
     
         33 - 37 . (canceled)